What is Energy? Is Energy conserved?

Special Cyber deal! Every purchase of a 2-year plan will get you 1 additional month free AND a surprise gift. Go to nordvpn.org/Sabine and use our coupon Sabine at checkout.
In this video I explain what physicists mean by "energy", how it is defined, why it is always conserved, what the difference is between "energy" and "free energy", why actually energy is not always conserved, and why this still makes sense.
#physics #science #education
0:00 Intro
0:45 Basic Properties of Energy
1:55 Mathematical Definition
4:02 Free Energy and Heat
6:39 Energy in General Relativity
8:46 Summary
9:04 Sponsor Message

[@rayzorrayzor9000]

I’ve always wondered what energy really is, I’ve searched through many pages and internet sites over the years and now finally I know Sabine is gonna put me straight - I’m gonna watch this vid with awe ! A Big Thankyou Sabine , now to settle down and watch years of wondering be answered in your vid .

[@jaimeduncan6167]

She is simple the best I have found, by wide margin.

[@larryscott3982]

I didn’t glean from this what energy is. Rather description(s) of behavior. Valuable nonetheless in my attempt to hold on. Some of my free energy used by my brain may have been lost to entropy, but it’s by degree. Call it efficiency of learning. Because some of it was useful.

[@cz19856]

​@@larryscott3982 energy is just the quantity that is conserved under time translations, you define it like that. The quantity that is conserved can take many forms, depending on the problem and the variables you take into account. For example: in the problem with the rollercoaster, the quantity 1/2*m*v^2 + m*g*h (kinetic energy plus potential energy) is conserved, while the quantity m*v^2 + m*g*h is not conserved. We call the first one the energy of the system, while the second quantity is useless and has no name. It is not conserved under time translations, therefore it is not energy.

[@janpahl6015]

even with expanding universe energy IS conserved. Any electromagnetic wave forced to occupy a larger "chuck" of space-time had to conserve its original energy per volume with the current energy per volume... otherwise energy will be a quantity that increases with time

[@ZsoltCseresznye]

@@cz19856 This part I also miss from Sabine's explanation. Would you help me to understand more clearly? For example the number of the cars in the rollercoster is also conserved in time, but this amount is not considered as energy. I'd be thankful if you could explain more clearly how can energy come from Noether's theorem. Thanks

[@Entropy3ko]

I remember reading the Feynman lectures, where he says: "We do not know what energy is, but we know how to measure it"

[@RedRocket4000]

Correct.

[@KibyNykraft]

Sure, but a kid could easily say the same thing. That does not tell us anything, it is just a habitual statement to fill out the lines of a book to be sold. What happens when we measure? How do we measure? What is a measurement. A measurement is an interaction of particles. These exchange their "presence", they change their mechanical dynamics by interactivity. This is what changes the energy outcome or the energy preservation or the energy measurement. We can't understand anything about energy until we accept nature as mechanistic. You know, that is the opposite of esoterica(which is the main problem in/of pseudoscience)

[@brunoborma]

@@KibyNykraft I think a child may say the same, but without embeding the baffling that the assumption carries in a phisicist assuming thr same thing. I think you are right about the pragmatic mechanicist understanding of energy. But the question of what energy really is is also a scientific affair, actually this kind of epistemological question gave birth to the scientific curiosity about nature. It is as if we wanted to make the concept clear to the eyes, so we can really know what we are dealing with. We don't want just to dominate and mold nature, but also understand and feel our interaction with it.

[@bebopbountyhead]

@@KibyNykraft Wouldn't a measurement be a description of what energy does, rather than what energy is? I would think that the only way to get around it is to establish energy as an inherent power of matter. However, as far as I can figure, that would establish energy as something that cannot be defined by our conventional means of scientific inquiry, as it is not something that is empirically evidenced, but rather inferred of empirical evidence.

[@kennythelenny6819]

@@KibyNykraft Would you say that for example when one is about to cross the road and seeing if it's clear to pass a type of energy measurement? Or as you type on your screen unconsciously tempering the degree of tactile interaction with a keyboard? I ask this because the term measurement is given but in my perception, It only refers to doing experiment in a high tech lab, which isolates me from comprehending what measurement is. The above examples I've cited at least to me seem like interactions since I'm intersecting to reveal my presence to other matter. Hopefully I've conveyed my thought process and understand why I'm asking that.

[@sjzara]

I went through three scientific degrees involving thermodynamics and this is the first clear definition of free energy I have heard. Thank you!

[@hyperduality2838]

Energy is duality, duality is energy! Potential energy is dual to kinetic energy. Apples fall to the to ground because they are conserving duality. The conservation of duality (energy) is the 5th law of thermodynamics. Gravitation is equivalent or dual to acceleration -- Einstein's happiest thought, the principle of equivalence (duality). Electro is dual to magnetic -- Maxwell's equations. Photons, light or electro-magnetic energy is dual. Positive charge is dual to negative charge -- electric charge. North poles are dual to south poles -- magnetic fields. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. "Always two there are" -- Yoda. Energy is measured in Joules (Jewels) or duals!

[@leif1075]

Wait but thebfirst law thermodumanics says energy is always conserved..and I've never heard that einstein's theories state it is not..

[@hyperduality2838]

@@leif1075 Energy is duality, duality is energy. Potential energy is dual to kinetic energy -- gravitational energy is dual. Electro is dual to magnetic -- photons are dual, waves are dual to particles -- quantum duality. Watch the following video about the antinomies or dualities of Immanuel Kant:- kzbin.info/www/bejne/baqzoax6aNaXrpY Beginning (finite) is dual to eternal (infinite). Simplicity is dual to complexity, simple (elementary, atomic, holistic) is dual to composite (molecules, reductive). Freewill (randomness, entropy) is dual to order (deterministic, predictability, syntropy). God (thesis ) is dual to the Christ consciousness (anti-thesis) creates the holy spirit or the mind/soul. Thesis is dual to anti-thesis creates converging thesis or synthesis -- the time independent Hegelian dialectic. Hegel's cat:- Alive (thesis, being) is dual to not alive (anti-thesis, non being) -- Schrodinger's or Plato's cat. Being is dual to non being creates becoming -- Plato. In physics everything is made out of energy (duality)! Conceptualism (universals) is dual to nominalism (non universal) creates realism. Realism (reality) is synthesized by duality, duality creates reality! "Always two there are" -- Yoda. The conservation of duality (energy) -- the 5th law of thermodynamics.

[@meinbherpieg4723]

@@leif1075 The law of thermodynamics was written by Newton who believed in a static interpretation of the universe. Now that we know the universe expands, the wave lengths of all particles will eventually stretch ( red shift) until the frequency is flattened.

[@leif1075]

@@meinbherpieg4723 doesnt really answer my question but thanks..

[@Nostradamus_Order33]

I always wait to drink my beer until Sabine says “Einstein”.

[@dennisliebig7622]

I take my cappuccino...gives a comparable same energy if enough caffeine is inside. Energyconservation can be tasted...

[@frankdimeglio8216]

@@dennisliebig7622 THE ULTIMATE AND CLEAR MATHEMATICAL PROOF OF THE FACT THAT E=MC2 IS F=MA: Ultimately and truly, TIME is NECESSARILY possible/potential AND actual IN BALANCE; AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. This NECESSARILY represents, INVOLVES, AND DESCRIBES what is possible/potential AND actual IN BALANCE. SO, time DILATION ULTIMATELY proves ON BALANCE that E=mc2 IS F=ma; AS ELECTROMAGNETISM/energy is gravity. The stars AND PLANETS are POINTS in the night sky. A PHOTON may be placed at the center of THE SUN (as A POINT, of course), AS the reduction of SPACE is offset by (or BALANCED with) the SPEED OF LIGHT; AS ELECTROMAGNETISM/ENERGY IS GRAVITY; AS E=mc2 IS F=ma. Great !!! "Mass"/ENERGY IS GRAVITY. ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy. E=MC2 IS F=MA. Consider the man who IS standing on what is the EARTH/ground. Touch AND feeling BLEND, as ELECTROMAGNETISM/energy is gravity; as E=mc2 IS F=ma. GREAT !!! E=mc2 IS F=ma. The linked AND BALANCED opposite of what is THE SUN is A POINT in the night sky. The stars AND PLANETS are POINTS in the night sky. A PHOTON may be placed at the center of THE SUN (as A POINT, of course), AS the reduction of SPACE is offset by (or BALANCED with) the SPEED OF LIGHT; AS ELECTROMAGNETISM/ENERGY IS GRAVITY; AS E=mc2 IS F=ma. This NECESSARILY represents, INVOLVES, AND DESCRIBES what is possible/potential AND actual IN BALANCE. Therefore, the linked AND BALANCED opposite of what is THE EARTH is ALSO A POINT in the night sky. Great. Gravity IS ELECTROMAGNETISM/energy. ELECTROMAGNETISM/ENERGY IS GRAVITY. E=mc2 IS F=ma. Gravity AND ELECTROMAGNETISM/ENERGY are linked AND BALANCED opposites, AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Accordingly, the Earth AND the Sun are linked AND BALANCED opposites; AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy, AS E=mc2 IS F=ma. The stars AND PLANETS are POINTS in the night sky. It ALL CLEARLY makes perfect sense. Great !!!!!! Energy has/involves GRAVITY, AND ENERGY has/involves inertia/INERTIAL RESISTANCE. E=MC2 IS F=MA. The EARTH and the SUN thus constitute and comprise what are the MIDDLE AND THE FULL DISTANCE in/of SPACE (IN BALANCE) in full and BALANCED compliance and conformity with the CLEAR and universal fact that E=mc2 IS F=ma, AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Great !!!! It ALL CLEARLY does make perfect sense. (The stars AND PLANETS are POINTS in the night sky.) INDEED, BALANCE and completeness go hand in hand. Now, very importantly, outer "space" involves full inertia; AND it is fully invisible AND black. Great. NOW, OVERLAY what is THE EYE in BALANCED RELATION to/WITH what is THE EARTH. Notice the black space of THE EYE. The stars AND PLANETS are POINTS in the night sky. THE DOME of a person's EYE is ALSO VISIBLE. Now, carefully consider what is the semi-spherical, translucent, QUANTUM GRAVITATIONAL, AND BLUE SKY. Great. E=mc2 IS F=ma. It is CLEAR. THE EARTH is ALSO BLUE (AS WATER). GREAT. "Mass"/ENERGY IS GRAVITY. ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy. INSTANTANEITY is thus FUNDAMENTAL to what is the FULL and proper UNDERSTANDING of physics/physical experience, as E=mc2 IS F=ma; as ELECTROMAGNETISM/energy is gravity. Gravity IS ELECTROMAGNETISM/energy. It ALL CLEARLY makes perfect sense. Inertia/INERTIAL RESISTANCE is proportional to (or BALANCED with/as) GRAVITATIONAL force/energy, as this unifies AND balances gravity AND ELECTROMAGNETISM/energy; as this balances gravity AND inertia. (This clearly explains BOTH F=ma AND E=mc2, AS ELECTROMAGNETISM/ENERGY IS GRAVITY !!!) ACCORDINGLY, gravity/acceleration involves BALANCED inertia/INERTIAL RESISTANCE; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. SO, the BALANCE of being AND EXPERIENCE is essential; AS E=mc2 IS F=ma. Our EXPERIENCE is NECESSARILY that of what is the FULL DISTANCE in/of SPACE, AS we are BALANCED between what are THE SUN AND c (A POINT); AS E=mc2 IS F=ma. The stars AND PLANETS are POINTS in the night sky. SO, a given PLANET (INCLUDING WHAT IS THE EARTH) sweeps out equal areas in equal times; AND this is THEN consistent WITH/as F=ma, E=mc2, AND what is perpetual motion; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy. E=mc2 IS F=ma. BALANCE and completeness go hand in hand. It ALL CLEARLY does make perfect sense. THINK about what is QUANTUM GRAVITY. "Mass"/ENERGY involves BALANCED inertia/INERTIAL RESISTANCE consistent with/as what is BALANCED electromagnetic/gravitational force/ENERGY, AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Indeed, gravity/acceleration involves BALANCED inertia/INERTIAL RESISTANCE; AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Therefore, the rotation of WHAT IS THE MOON matches it's revolution !!! Objects fall at the SAME RATE (neglecting air resistance, of course), AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy. Gravitational force/ENERGY is proportional to (or BALANCED with/as) inertia/INERTIAL RESISTANCE; AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Stellar clustering ALSO proves ON BALANCE that ELECTROMAGNETISM/energy is gravity, AS E=mc2 IS F=ma. Magnificent !!! E=mc2 IS F=ma. Is a two dimensional surface or SPACE visible or invisible ? The answer is that it is BOTH. So, the electron AND photon are structureless. A PLANET (INCLUDING WHAT IS THE EARTH) is a balanced MIDDLE DISTANCE form in relation to E=mc2 AS F=ma. A PLANET (INCLUDING WHAT IS THE EARTH) is a balanced MIDDLE DISTANCE form in relation to the Sun AND c (A POINT). The stars AND PLANETS are POINTS in the night sky. E=MC2 IS F=MA. ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy. Gravity AND ELECTROMAGNETISM/energy are linked AND BALANCED opposites, AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. BALANCE AND completeness go hand in hand. Very importantly, outer "space" involves full inertia; AND it is fully invisible AND black. E=MC2 IS F=MA. It ALL CLEARLY makes perfect sense. The BALANCE of being AND EXPERIENCE is essential. The INTEGRATED EXTENSIVENESS of THOUGHT (AND description) is improved in the truly superior mind. INSTANTANEITY is thus FUNDAMENTAL to what is the FULL and proper UNDERSTANDING of physics/physical experience. (THOUGHTS ARE INVISIBLE.) It is a very great truth that THE SELF represents, FORMS, and experiences a COMPREHENSIVE approximation of experience in general by combining conscious and unconscious experience. MOREOVER, the ability of THOUGHT to DESCRIBE OR RECONFIGURE sensory experience is ULTIMATELY dependent upon the extent to which THOUGHT IS SIMILAR TO sensory experience. Beautiful. It ALL CLEARLY makes perfect sense. E=mc2 IS F=ma. By Frank DiMeglio

[@UncleKennysPlace]

@@frankdimeglio8216 Failed AI, obviously.

[@frankdimeglio8216]

HOW AND WHY STELLAR CLUSTERING ALSO CLEARLY PROVES (ON BALANCE) THAT ELECTROMAGNETISM/ENERGY IS GRAVITY, AS E=MC2 IS F=MA IN WHAT IS A UNIVERSAL AND BALANCED FASHION: "Mass"/ENERGY are linked AND balanced, as gravity AND ELECTROMAGNETISM/energy are linked AND balanced; as ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity/acceleration involves balanced inertia/inertial resistance, as ELECTROMAGNETISM/energy IS gravity. E=mc2 IS F=ma. Gravity AND ELECTROMAGNETISM/energy are linked AND BALANCED opposites, AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Clearly, it is, therefore, explained (ON BALANCE) why the star POINTS would then be relatively or relationally CLOSER OR integrated. BALANCE AND completeness go hand in hand. The Sun is BOTH equations IN BALANCE. Now, outer "space" involves full inertia; AND it is fully invisible AND black. SO, it is CLEARLY proven that E=mc2 IS F=ma in a BALANCED fashion; AS ELECTROMAGNETISM/energy is gravity. Great. Gravity IS ELECTROMAGNETISM/energy. Energy has/involves GRAVITY, AND ENERGY has/involves inertia/INERTIAL RESISTANCE. It ALL CLEARLY makes perfect sense, as E=mc2 IS F=ma. Indeed, this NECESSARILY represents, INVOLVES, AND DESCRIBES what is possible/potential AND actual IN BALANCE. PERFECT. By Frank DiMeglio

[@lukidurer28]

@@frankdimeglio8216 Dude I think you forgot to calculate the emerging spiritual resonance of our consciousness with the universal wave function interference superposition with regards to us being entangled

[@kcflick6132]

Heat: you wanted to see me in your office? Boss: yes, I hear you dont do any work and are useless. Heat: thats cold

[@chrisbovington9607]

Ha! Nice wordplay. 🙂

[@tomutube3138]

Excellent explanation of a topic with underappreciated complexity! No simplifications, no dumbing down, yet easy to follow. Thanks!

[@Scottygthreethousand]

@A CB Well mass is energy. Not sure about volume.

[@placidesulfurik]

@A CB You misunderstood the definition. Any conserved quantity in a system with time-translation invariance is not, by definition, energy. How ever, any time-translation invariant system must have a particular quantity that is conserved, which can be verified mathematically. This particular quantity is given the name "energy" (hence why energy is, by definition, conserved), and has the dimensions of Planck's constant divided by time.

[@alwaysdisputin9930]

@@placidesulfurik Your explanation's BS. Say we're experimenting with fart gas & our experiment gives the same results no matter what time you run it, thus it has "time translation invariance". We find the amount of fart gas & the bad smell are both conserved quantities. But you don't define these to be energy. Instead you find a *3rd* conserved quantity & give it the name "energy". It just seems to be a completely arbitrary choice & you could equally have said "farts = energy"

[@fluentpiffle]

All things are 'energy'. We currently call it 'space', and the reason it is conserved is because it exists infinitely, so it is always 'everywhere'. Essentially, it is 'that which exists', as its spherical wave-motions become the 'particle effect' we call 'matter', which are subsequently returned to a purely 'energetic' state with events such as 'black holes' .. "Commendation from NASA for research work at Massachusetts Institute of Technology on the Earth's atmosphere and the Moon's surface for navigation of the Apollo spacecraft to the Moon.. Dr. Milo Wolff has found the structure of the electron consisting of two spherical quantum waves, one moving radially outward and another moving radially inward. The center of the waves is the nominal location of the electron 'particle'. These waves extend infinitely, like charge force. All 'particle' waves mix and contribute to each other, thus all matter of the universe is interrelated by this intimate connection between the fundamental 'particles' and the universe. The natural laws are a direct consequence of this Wave Structure of Matter (WSM), thus WSM underlies all of science." spaceandmotion

[@dinobotpwnz]

The only slight simplification was considering the expanding universe as a fixed background instead of something subject to backreaction from the experiment.

[@smartscience5305]

Hello, I am 12 years old, and I am admired by your great lessons, also about quantum physics, you are great!

[@SabineHossenfelder]

Happy to hear!

[@David-km2ie]

Wow, you are a born physicist

[@smartscience5305]

@@David-km2ie thank you friend , my dream is to be an astrophysicist, so I am learning quantum , electromagnetism and thermodynamics.😁😊

[@frankdimeglio8216]

@@SabineHossenfelder THE THEORETICAL, SIMPLE, ULTIMATE, CLEAR, LINKED, BALANCED, AND EXTENSIVE MATHEMATICAL UNIFICATION OF PHYSICS/PHYSICAL EXPERIENCE IS PROVEN, AS E=MC2 IS F=MA: Very importantly, outer "space" involves full inertia; AND it is fully invisible AND black. Energy has/involves GRAVITY, AND ENERGY has/involves inertia/INERTIAL RESISTANCE. The perpetual motion of THE PLANETS in RELATION to WHAT IS THE SUN is the result of the fact that gravity/acceleration involves BALANCED inertia/INERTIAL RESISTANCE, as this IS proven by F=ma AND E=mc2. GREAT !!!! ACCORDINGLY, a given PLANET sweeps out equal areas in equal times; AS GRAVITY IS ELECTROMAGNETISM/ENERGY. THEREFORE, this NECESSARILY represents, involves, and describes what is MOTION AND NO MOTION IN BALANCE. SO, THE SPEED OF LIGHT (c) IS THEN understood as a POINT; AS the SPACE that envelopes THE EARTH IN BALANCE IS the MIDDLE DISTANCE in/of SPACE. E=mc2 IS F=ma, AS time DILATION ULTIMATELY proves that electromagnetism/ENERGY IS GRAVITY. (BALANCE and completeness go hand in hand.) Gravity IS ELECTROMAGNETISM/energy. Indeed, gravity AND ELECTROMAGNETISM/energy are linked AND BALANCED opposites; AS ELECTROMAGNETISM/energy is gravity. Again, E=mc2 IS F=ma. OVERLAY what is THE EYE in BALANCED RELATION to/with WHAT IS THE EARTH. NOW, LOOK at what is the translucent, semi-spherical, AND BLUE SKY. THE EARTH is ALSO blue. SO, objects fall at the SAME RATE (neglecting air resistance, of course); AS E=mc2 IS F=ma; AS electromagnetism/ENERGY IS GRAVITY. Great. Gravity IS ELECTROMAGNETISM/energy. ELECTROMAGNETISM/ENERGY IS GRAVITY. This is proven by F=ma AND E=mc2. Indeed, a PHOTON may be placed at the center of THE SUN (as a POINT, of course); as the reduction of SPACE is offset by (or BALANCED with) the SPEED OF LIGHT (c). GREAT. ELECTROMAGNETISM/energy IS gravity. This is proven by F=ma AND E=mc2. "Mass"/energy involves balanced inertia/inertial resistance consistent with/as what is BALANCED electromagnetic/gravitational force/energy, as electromagnetism/energy is gravity. Gravity AND electromagnetism/energy are linked AND balanced, as electromagnetism/ENERGY IS GRAVITY. ACCORDINGLY, gravity/acceleration involves balanced inertia/inertial resistance; as gravity IS ELECTROMAGNETISM/energy. The stars AND PLANETS are POINTS in the night sky. Objects fall at the SAME RATE (neglecting air resistance, of course), AS ELECTROMAGNETISM/energy is gravity. E=mc2 IS F=ma. Gravity IS ELECTROMAGNETISM/energy. Carefully consider what is THE EYE along with the falling man. "Mass"/ENERGY IS GRAVITY. ELECTROMAGNETISM/ENERGY IS GRAVITY. ELECTROMAGNETISM/ENERGY IS GRAVITY. This is proven by F=ma AND E=mc2. (E=mc2 is directly and FUNDAMENTALLY DERIVED FROM F=ma, as ELECTROMAGNETISM/ENERGY IS GRAVITY. That is where Einstein got it from.) This NECESSARILY represents, involves, AND describes what is possible/potential AND actual IN BALANCE. THOUGHTS are invisible. Very importantly, the ability of THOUGHT to DESCRIBE OR RECONFIGURE sensory experience is ULTIMATELY dependent upon the extent to which thought is SIMILAR to sensory experience. SO, BOTH equations apply to, represent, AND perfectly describe the MIDDLE DISTANCE in/of SPACE as invisible AND VISIBLE ELECTROMAGNETIC/GRAVITATIONAL SPACE in FUNDAMENTAL equilibrium AND BALANCE; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. The BALANCE of being AND EXPERIENCE is essential. "Mass"/ENERGY IS GRAVITY. ELECTROMAGNETISM/ENERGY IS GRAVITY. Consider THE MAN who is standing on WHAT IS the EARTH/GROUND. Touch AND feeling BLEND, AS ELECTROMAGNETISM/ENERGY IS GRAVITY. E=mc2 IS F=ma. Gravity IS ELECTROMAGNETISM/energy. It ALL CLEARLY makes perfect sense. Take careful notice of WHAT IS THE ORANGE SUN. Beautiful. Now, carefully consider the role and RELATIONAL significance of what is the eyelid. Consider what is lava. The viscosity of lava is BETWEEN that of what is water AND what is the Earth/ground. Gravity IS ELECTROMAGNETISM/energy. E=mc2 IS F=ma. ELECTROMAGNETISM/energy is gravity. Time DILATION ALSO ULTIMATELY proves that GRAVITY IS ELECTROMAGNETISM/ENERGY. E=mc2 IS F=ma. Indeed, this not only explains the term c4; but it ALSO explains the significance of the fourth spatial dimension. GREAT !!! Notice that THE DOME of a person's EYE may also be visible. THINK. IT IS CLEARLY PROVEN. "Mass"/ENERGY IS GRAVITY. ELECTROMAGNETISM/ENERGY IS GRAVITY. The stars AND PLANETS are POINTS in the night sky. INSTANTANEITY is thus FUNDAMENTAL to what is the FULL and proper understanding of physics/physical experience, AS ELECTROMAGNETISM/ENERGY IS GRAVITY. E=mc2 IS F=ma, AS gravity/acceleration involves BALANCED inertia/INERTIAL RESISTANCE; AS the rotation of WHAT IS THE MOON matches it's revolution. Moreover, objects fall at the SAME RATE (neglecting air resistance, of course); AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy. INSTANTANEITY is thus FUNDAMENTAL to what is the FULL and proper understanding of physics/physical experience, AS ELECTROMAGNETISM/energy is gravity. Ultimately and truly, time is NECESSARILY possible/potential AND actual IN BALANCE; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. (E=mc2 IS F=ma.) This NECESSARILY represents, INVOLVES, AND describes what is possible/potential AND actual IN BALANCE, AS ELECTROMAGNETISM/ENERGY IS GRAVITY. The INTEGRATED EXTENSIVENESS of thought (AND description) is improved in the truly superior mind. THINK. Gravity IS ELECTROMAGNETISM/energy. Time DILATION ULTIMATELY proves that electromagnetism/ENERGY IS GRAVITY, AS E=mc2 IS F=ma. The full distance in/of SPACE is thus LINKED and BALANCED with what is the middle distance in/of SPACE, AS ELECTROMAGNETISM/ENERGY IS GRAVITY. E=mc2 IS F=ma. GREAT !!!! The stars AND PLANETS are POINTS in the night sky. SO, stellar clustering ALSO proves that electromagnetism/ENERGY IS GRAVITY. Carefully consider what is A GALAXY. (BALANCE AND completeness go hand in hand.) By Frank DiMeglio

[@frankdimeglio8216]

Hossenfelder is knowingly and deceitfully lying about the fundamentals regarding physics/physical experience. Ask her about Frank DiMeglio. She is STILL lying her head off. Frank DiMeglio is RECOGNIZED as having surpassed Newton and Einstein.

[@tomfleenor7555]

I am so delighted to have discovered this channel. Sabine has such a wonderful grasp on these concepts and does such a spectacular job of translating what seem to be impossibly difficult ideas into readily consumable lessons.

[@justchecking905]

I'm a retired scientist - applied physics and elecctrical engineering - with an insatiable wish to increasing my knowledge and understanding of all things science. Your clear and unconventional way of expalining so many topics has fed that hunger ever since I discovered you on KZbin a few months ago. I applaud what you do. Keep it coming!

[@hyperduality2838]

Energy is duality, duality is energy! Potential energy is dual to kinetic energy. Apples fall to the to ground because they are conserving duality. The conservation of duality (energy) is the 5th law of thermodynamics. Gravitation is equivalent or dual to acceleration -- Einstein's happiest thought, the principle of equivalence (duality). Electro is dual to magnetic -- Maxwell's equations. Photons, light or electro-magnetic energy is dual. Positive charge is dual to negative charge -- electric charge. North poles are dual to south poles -- magnetic fields. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. "Always two there are" -- Yoda. Energy is measured in Joules (Jewels) or duals! Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics. Teleological physics (syntropy) is dual to non-teleological physics (entropy) -- Shannon information theorem.

[@buddinghumanist6285]

We need a Sabine Hossenfelder for every scientific discipline.

[@BulentBasaran]

Clarity in perception and clarity in thinking result in clarity in discourse. Sabine is indeed a good role model.

[@frankdimeglio8216]

Ridiculous. She is lying about physics. Here are the FUNDAMENTALS. THE ULTIMATE AND CLEAR MATHEMATICAL PROOF OF THE FACT THAT E=MC2 IS F=MA: Ultimately and truly, TIME is NECESSARILY possible/potential AND actual IN BALANCE; AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. This NECESSARILY represents, INVOLVES, AND DESCRIBES what is possible/potential AND actual IN BALANCE. SO, time DILATION ULTIMATELY proves ON BALANCE that E=mc2 IS F=ma; AS ELECTROMAGNETISM/energy is gravity. The stars AND PLANETS are POINTS in the night sky. A PHOTON may be placed at the center of THE SUN (as A POINT, of course), AS the reduction of SPACE is offset by (or BALANCED with) the SPEED OF LIGHT; AS ELECTROMAGNETISM/ENERGY IS GRAVITY; AS E=mc2 IS F=ma. Great !!! "Mass"/ENERGY IS GRAVITY. ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy. E=MC2 IS F=MA. Consider the man who IS standing on what is the EARTH/ground. Touch AND feeling BLEND, as ELECTROMAGNETISM/energy is gravity; as E=mc2 IS F=ma. GREAT !!! E=mc2 IS F=ma. The linked AND BALANCED opposite of what is THE SUN is A POINT in the night sky. The stars AND PLANETS are POINTS in the night sky. A PHOTON may be placed at the center of THE SUN (as A POINT, of course), AS the reduction of SPACE is offset by (or BALANCED with) the SPEED OF LIGHT; AS ELECTROMAGNETISM/ENERGY IS GRAVITY; AS E=mc2 IS F=ma. This NECESSARILY represents, INVOLVES, AND DESCRIBES what is possible/potential AND actual IN BALANCE. Therefore, the linked AND BALANCED opposite of what is THE EARTH is ALSO A POINT in the night sky. Great. Gravity IS ELECTROMAGNETISM/energy. ELECTROMAGNETISM/ENERGY IS GRAVITY. E=mc2 IS F=ma. Gravity AND ELECTROMAGNETISM/ENERGY are linked AND BALANCED opposites, AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Accordingly, the Earth AND the Sun are linked AND BALANCED opposites; AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy, AS E=mc2 IS F=ma. The stars AND PLANETS are POINTS in the night sky. It ALL CLEARLY makes perfect sense. Great !!!!!! Energy has/involves GRAVITY, AND ENERGY has/involves inertia/INERTIAL RESISTANCE. E=MC2 IS F=MA. The EARTH and the SUN thus constitute and comprise what are the MIDDLE AND THE FULL DISTANCE in/of SPACE (IN BALANCE) in full and BALANCED compliance and conformity with the CLEAR and universal fact that E=mc2 IS F=ma, AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Great !!!! It ALL CLEARLY does make perfect sense. (The stars AND PLANETS are POINTS in the night sky.) INDEED, BALANCE and completeness go hand in hand. Now, very importantly, outer "space" involves full inertia; AND it is fully invisible AND black. Great. NOW, OVERLAY what is THE EYE in BALANCED RELATION to/WITH what is THE EARTH. Notice the black space of THE EYE. The stars AND PLANETS are POINTS in the night sky. THE DOME of a person's EYE is ALSO VISIBLE. Now, carefully consider what is the semi-spherical, translucent, QUANTUM GRAVITATIONAL, AND BLUE SKY. Great. E=mc2 IS F=ma. It is CLEAR. THE EARTH is ALSO BLUE (AS WATER). GREAT. "Mass"/ENERGY IS GRAVITY. ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy. INSTANTANEITY is thus FUNDAMENTAL to what is the FULL and proper UNDERSTANDING of physics/physical experience, as E=mc2 IS F=ma; as ELECTROMAGNETISM/energy is gravity. Gravity IS ELECTROMAGNETISM/energy. It ALL CLEARLY makes perfect sense. Inertia/INERTIAL RESISTANCE is proportional to (or BALANCED with/as) GRAVITATIONAL force/energy, as this unifies AND balances gravity AND ELECTROMAGNETISM/energy; as this balances gravity AND inertia. (This clearly explains BOTH F=ma AND E=mc2, AS ELECTROMAGNETISM/ENERGY IS GRAVITY !!!) ACCORDINGLY, gravity/acceleration involves BALANCED inertia/INERTIAL RESISTANCE; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. SO, the BALANCE of being AND EXPERIENCE is essential; AS E=mc2 IS F=ma. Our EXPERIENCE is NECESSARILY that of what is the FULL DISTANCE in/of SPACE, AS we are BALANCED between what are THE SUN AND c (A POINT); AS E=mc2 IS F=ma. The stars AND PLANETS are POINTS in the night sky. SO, a given PLANET (INCLUDING WHAT IS THE EARTH) sweeps out equal areas in equal times; AND this is THEN consistent WITH/as F=ma, E=mc2, AND what is perpetual motion; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy. E=mc2 IS F=ma. BALANCE and completeness go hand in hand. It ALL CLEARLY does make perfect sense. THINK about what is QUANTUM GRAVITY. "Mass"/ENERGY involves BALANCED inertia/INERTIAL RESISTANCE consistent with/as what is BALANCED electromagnetic/gravitational force/ENERGY, AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Indeed, gravity/acceleration involves BALANCED inertia/INERTIAL RESISTANCE; AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Therefore, the rotation of WHAT IS THE MOON matches it's revolution !!! Objects fall at the SAME RATE (neglecting air resistance, of course), AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy. Gravitational force/ENERGY is proportional to (or BALANCED with/as) inertia/INERTIAL RESISTANCE; AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Stellar clustering ALSO proves ON BALANCE that ELECTROMAGNETISM/energy is gravity, AS E=mc2 IS F=ma. Magnificent !!! E=mc2 IS F=ma. Is a two dimensional surface or SPACE visible or invisible ? The answer is that it is BOTH. So, the electron AND photon are structureless. A PLANET (INCLUDING WHAT IS THE EARTH) is a balanced MIDDLE DISTANCE form in relation to E=mc2 AS F=ma. A PLANET (INCLUDING WHAT IS THE EARTH) is a balanced MIDDLE DISTANCE form in relation to the Sun AND c (A POINT). The stars AND PLANETS are POINTS in the night sky. E=MC2 IS F=MA. ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy. Gravity AND ELECTROMAGNETISM/energy are linked AND BALANCED opposites, AS E=mc2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. BALANCE AND completeness go hand in hand. Very importantly, outer "space" involves full inertia; AND it is fully invisible AND black. E=MC2 IS F=MA. It ALL CLEARLY makes perfect sense. The BALANCE of being AND EXPERIENCE is essential. The INTEGRATED EXTENSIVENESS of THOUGHT (AND description) is improved in the truly superior mind. INSTANTANEITY is thus FUNDAMENTAL to what is the FULL and proper UNDERSTANDING of physics/physical experience. (THOUGHTS ARE INVISIBLE.) It is a very great truth that THE SELF represents, FORMS, and experiences a COMPREHENSIVE approximation of experience in general by combining conscious and unconscious experience. MOREOVER, the ability of THOUGHT to DESCRIBE OR RECONFIGURE sensory experience is ULTIMATELY dependent upon the extent to which THOUGHT IS SIMILAR TO sensory experience. Beautiful. It ALL CLEARLY makes perfect sense. E=mc2 IS F=ma. By Frank DiMeglio

[@fathare2085]

Exactly. We need a badass in all science and engineering disciplines.

[@fathare2085]

@@frankdimeglio8216 Are you really serious? This is hodgepodge gobbledygook. By the 2nd paragraph I knew what you're saying is nonsense but I still started reading the 3rd paragraph and then gave up. Scrolling down your long "lecture" I see you spent time and energy on this and must really be serious. I suggest you clear away all of what you "know" of physics and start again learning the correct fundamentals. On the chance that you're trolling and have time to waste then I can only say get a life! Or maybe take your meds?

[@KibyNykraft]

She is talking about "different energies". Well that does not tell us anything unless we have proved or postulated that energy are some form of matter or dark particles or counter-charge field.

[@mirador698]

Citing The Science Asylum regarding the usability of energy: „Gradients are everything!“ You can use heat if there is something hotter or colder nearby.

[@ps200306]

Yep, that's why God or the Anthropic Principle made such a big expanding universe. No use living near a star if it's floating in a heat bath as hot as itself.

[@hyperduality2838]

Energy is duality, duality is energy! Potential energy is dual to kinetic energy. Apples fall to the to ground because they are conserving duality. The conservation of duality (energy) is the 5th law of thermodynamics. Gravitation is equivalent or dual to acceleration -- Einstein's happiest thought, the principle of equivalence (duality). Electro is dual to magnetic -- Maxwell's equations. Photons, light or electro-magnetic energy is dual. Positive charge is dual to negative charge -- electric charge. North poles are dual to south poles -- magnetic fields. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. "Always two there are" -- Yoda. Energy is measured in Joules (Jewels) or duals!

[@projectmalus]

@@hyperduality2838 The apple example is cool :) I can see how duality is conserved when the movement of the apple in one part of the system gives the ability to move back, at some other part of the local system. But is duality dependent on a sort of analog universe that is oscillations in fields? What happens if that analog display of energy movement is digitized? As far as I understand the standard model, there were two types of universe, the very early one before particles had mass and then the one we see with mass. If that very early universe had essentially different, slower time or no time at all then that universe would be more like an object, a particle instead of a wave as it were. Perhaps this is still present along with the later universe. Think of it as a series of flash images, each an object, strung together like beads but essentially separate objects each of which contain the entirety. Hilbert curve? The oscillations move the images along so it appears to move, there appears to be movement, but it could be just our perception. Perhaps duality is valid but there could be this other thing too, like an artifact from the very early universe embedded in the one we see.

[@hyperduality2838]

@@projectmalus Potential energy is being converted into kinetic or real energy via duality being conserved -- gravity. Positive curvature is dual to negative curvature -- Gauss, Riemann geometry. Curvature or gravitation is therefore dual. Negative curvature does not exist in Einstein's theory of General Relativity, it is missing! Einstein ignored negative curvature and did not provide us with a reason for doing this. Dark energy or repulsive gravity = negative curvature or hyperbolic geometry. The conservation of duality means that negative curvature must some how be incorporated into General Relativity. This is why duality is important and also why a 5th law is needed. Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics. "Through imagination and reason we turn experience into foresight (prediction)" -- Spinoza describing syntropy. Teleological physics (syntropy) is dual to non-teleological physics (entropy). Dark energy is not a particle as portrayed by many physicists, it is empirical evidence of negative curvature and this important fact is being ignored by science. Mind (ideas) is dual to matter -- Descartes. Noumenal is dual to phenomenal -- Immanuel Kant. Absolute truth is dual to relative truth -- Hume's fork. Being is dual to non-being creates becoming -- Plato. Thesis is dual to anti-thesis creates converging thesis, synthesis -- the time independent Hegelian dialectic. A pattern of duality within philosophy. "Philosophy is dead" -- Stephen Hawking. Philosophy confirms the existence of duality but you cannot use it in physics. Duality allows for two new laws of thermodynamics!

[@projectmalus]

@@hyperduality2838 Philosophy might affirm duality in that it exists by moving, but I don't think it's dual natured. Instead, it might be that it bifurcates ceaselessly. It confers a duality upon that which it regards. To me, awareness is fundamental, not consciousness. It's possible that awareness came into the universe with particles achieving mass, and is being and movement expressed as one. Cleverness is engagement with the environment, combined with awareness forms intelligence. Consciousness is quite a different matter...no pun intended...in that (as I see it) humans have a DAC in their heads that creates a real time moving reality picture. Sense data is digitized by the way it moves thru the body. This emulates the creation of mass, where the field is created by one type of movement and then serves as a base to convert the digital to analogue. So consciousness is different than awareness. Awareness comes from the quantum world (IS the quantum world) and is embedded in the world of oscillations in fields. Awareness is not informational, but allows it. Awareness itself is not dual natured.

[@deathskunk3]

Thank you so much! I was the worst physics student in highschool and grew to dislike it but your crystal clear and thorough awakens my curiousity and am very grateful for that!

[@davidw4987]

"Save energy" to most people means "save money".

[@jmcsquared18]

Noether is likely the greatest mathematician to ever directly impact physics. I use her theorem and the techniques utilized by it too often to count.

[@clmasse]

In informal language, symmetry and conservation is about the same. Noether gives it a mathematical meaning in Lagrangian theories, but it is just a technical detail.

[@toddq6443]

@Null Pointer Thanks (sarc). More study required...oh boy. 😕

[@jjeherrera]

Noether was indeed one of the mathematicians who most influenced physics, but she doesn't compare to Euler.

[@jmcsquared18]

@@jjeherrera Why are we comparing people? Who exactly made this a competition?

[@clmasse]

@@jmcsquared18 You made it.

[@r7diego]

I follow a lot of physics channels but your style of explaining things is particularly different and interesting.

[@harrypalmer3481]

I've asked this question before when I was young to teachers & experts, the answers were unsatisfactory to the point of frustration only leading to more questions until I frustrated the teachers & others. Later on there was reading & investigation, then understanding about entropy... but, & anyway: this is the best, most concise, & entertaining explanation I've encountered, ever, anywhere, on the planet. The older me is grateful, the younger me is elated & wished you'd have been available for me to learn from a long time ago. I hope, & guess there must be many young, curious minds lapping this up. Regardless of age it seems there are plenty of people in the comments who feel somewhat the same - Danke Frau Hossenfelder!

[@eljcd]

What happens to the energy of redshifted photons is something that always confused me and never dare to ask. Thank you for clear it up!

[@32eoin32]

I don't think she's right. The light just appears to be red shifted because we're in a moving frame of reference to the source. If we listen to a 100hz tone while moving away at 1m/s we would measure a 99hz tone. I know light travels at the speed of light, but how we measure its frequency requires us to be in the same frame of reference to its source.

[@omarfarouk3848]

I think u shouldnt think of energy as something, think of it as just a number we associate to things

[@omarfarouk3848]

@@32eoin32 We cant compare light to sound, they r different, and in the example u mention we shoyld account for wind speed And in relativity the important things r the things from ur frame, it doesnt matter what other frames see, a photon frequency is the frequency that u measure, not the source

[@ps200306]

@@32eoin32 , the point of relativity is that there _is_ no privileged cosmological frame of reference. We measure the frequency of the Cosmic Microwave Background at 0.3 GHz in our frame of reference. When it was first emitted the frequency was a thousand times higher. But it's all around us, in every direction. What would you say is the appropriate frame of reference to measure it in?

[@32eoin32]

@@omarfarouk3848 one can compare light to sound. To say that you can't is just wrong. The double slit experiment is one example where you can compare them. Travelling through a vacuum can be compared also with different results. The source of the frequency matters, otherwise we wouldn't say it redshifted. We'd say it's infrared. If I'm travelling at a fast enough speed relative to you we'll see different frequencies yet the energy of the photons given out from the source was the same.

[@KeithRowley418]

Of all your videos so far, this is the one I've most enjoyed, my reasons being: 1) You have introduced me to terminology of which I was not aware, but which seems fundamental 2) You introduced me to a scientist of whom I have never before heard amnd 3) It leaves me wondering about the 'lost' energy arising from redshift. Thank you as always for the clarity of thought - excellent.

[@arraikcruor6407]

Which terminology?

[@KeithRowley418]

@@arraikcruor6407 "Free Energy" (speaking from memory and not watching the video again!)

[@fluentpiffle]

All things are 'energy'. We currently call it 'space', and the reason it is conserved is because it exists infinitely, so it is always 'everywhere'. Essentially, it is 'that which exists', as its spherical wave-motions become the 'particle effect' we call 'matter', which are subsequently returned to a purely 'energetic' state with events such as 'black holes' .. "Commendation from NASA for research work at Massachusetts Institute of Technology on the Earth's atmosphere and the Moon's surface for navigation of the Apollo spacecraft to the Moon.. Dr. Milo Wolff has found the structure of the electron consisting of two spherical quantum waves, one moving radially outward and another moving radially inward. The center of the waves is the nominal location of the electron 'particle'. These waves extend infinitely, like charge force. All 'particle' waves mix and contribute to each other, thus all matter of the universe is interrelated by this intimate connection between the fundamental 'particles' and the universe. The natural laws are a direct consequence of this Wave Structure of Matter (WSM), thus WSM underlies all of science." spaceandmotion

[@scalpol]

Finally a good explanation of energy, and just in about 9 minutes. Thank you Sabine for your amazing contributions to public knowledge!

[@david203]

Heat has low entropy if it is concentrated in volume, high entropy if not. Temperature is the measure of how concentrated it is. So heat always tends to flow from hot objects to cold.

[@alcyone1349]

This is one of the clearest and most precise videos on the concept of energy. Thank you Sabine!

[@mecidgaliba2854]

When I was a sophomore at a high school, my teacher tried to explain "free energy" to me. I was completely lost at that moment. After many years, I wish I had a chance to learn from you back then.

[@mecidgaliba2854]

@Wise and Free No, I'd have paid attention to her just like I did to my teacher. It wasn't about my listening, it was about my teacher teaching. I think that you haven't had enough education experience in realizing teaching skill differences among teachers. The teacher really matters.

[@Psy0psAgent]

@@mecidgaliba2854 a saying that demonstrates what you suggest could be, ‘the dog is no better than the master’ and another refers to ‘tis a poor student that does not surpass his teacher’, so I conclude you craved knowledge, but like most of us, did not get it from those supposedly entrusted to do so.

[@richardgeorge372]

I felt like I could actually follow what you were saying and learned something new! Thanks Sabine!

[@antogk]

Keep up the good work. We need people like you in schools!

[@paulryan2128]

Thanks, Sabine. I was trained as an engineer (applied science) in the '60s and, therefore, was unaware of the subtleties of energy conservation wrt an expanding universe. Wouldn't my Thermodynamics prof be surprised!

[@semmering1]

I am so happy, to get such excellent content for free in youtube. Thank you Sabine, it´s a pleasure to watch your videos.

[@alessandroboldrini3577]

Thank you Sabine, you helped me understanding the heuristic meaning of Noether’s Theorem! It was overshadowed by the deep and beautiful mathematics behind it

[@vhawk1951kl]

What is the differentiable function, and what its domain?

[@TheToffeyman]

Simply just thank you Sabine, for the first I finally feel that I have found an answer which satisfies my curiosity

[@garryslocombe]

Thank you Sabine for yet another wonderful video. There was only one bit that caused me to ask a question which wasn't answered. You explained beautifully how expanding space is expanding and therefore time invariance is lost. However, if space expands we have two measures of space and I haven't found anyone that describes the models using both measures. The two measures are the space the size as it was before expansion (A) and the space as it is, after expansion (B). It seems feasible/likely that models using A will not be time invariant but those using B, will be.

[@eddiegaltek]

I remember Brian Cox describing energy in one of his TV programs saying (I think), "For me energy is the length of the Time dimension in a Four Vector." But them went on to add, "That's probably not an awful lot of help, I'll admit," and for most of his viewers I think he was probably right.

[@SabineHossenfelder]

Yes, typical particle physicist's answer ;) Of course the four-vector in question belongs to a wave-function that technically is smeared out over the whole universe, so that quantity may be an energy, but it's difficult to say the energy of just what it is.

[@clmasse]

@@SabineHossenfelder It may be the 4-vector of a classical particle. Or in quantum mechanics, it need not be a plane wave. The wave function is only a device to calculate the probability of the result of an momentum-energy measure.

[@clmasse]

The conserved quantity associated to time translation is not any more helpful. Both are mathematical modelling, not the physical concept in itself. Brian Cox meant that the physicist is not better armed to understand this concept than the layman. This is a common problem with all the familiar concepts that are used in science.

[@rodschmidt8952]

Every different view helps!

[@hyperduality2838]

Energy is duality, duality is energy! Potential energy is dual to kinetic energy. Apples fall to the to ground because they are conserving duality. The conservation of duality (energy) is the 5th law of thermodynamics. Gravitation is equivalent or dual to acceleration -- Einstein's happiest thought, the principle of equivalence (duality). Electro is dual to magnetic -- Maxwell's equations. Photons, light or electro-magnetic energy is dual. Positive charge is dual to negative charge -- electric charge. North poles are dual to south poles -- magnetic fields. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. "Always two there are" -- Yoda. Energy is measured in Joules (Jewels) or duals! Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics. Teleological physics (syntropy) is dual to non-teleological physics (entropy) -- Shannon information theorem.

[@davewatson3833]

I propose that you write a book with the title: "Great Explanations" :-)

[@nt1441]

Thank you for demystifying this (arguably) most fundamental concept of all. It seems so easy to understand what really matters when you explain it. Math alone does not explain itself :)

[@fluentpiffle]

All things are 'energy'. We currently call it 'space', and the reason it is conserved is because it exists infinitely, so it is always 'everywhere'. Essentially, it is 'that which exists', as its spherical wave-motions become the 'particle effect' we call 'matter', which are subsequently returned to a purely 'energetic' state with events such as 'black holes' .. "Commendation from NASA for research work at Massachusetts Institute of Technology on the Earth's atmosphere and the Moon's surface for navigation of the Apollo spacecraft to the Moon.. Dr. Milo Wolff has found the structure of the electron consisting of two spherical quantum waves, one moving radially outward and another moving radially inward. The center of the waves is the nominal location of the electron 'particle'. These waves extend infinitely, like charge force. All 'particle' waves mix and contribute to each other, thus all matter of the universe is interrelated by this intimate connection between the fundamental 'particles' and the universe. The natural laws are a direct consequence of this Wave Structure of Matter (WSM), thus WSM underlies all of science." spaceandmotion

[@archaeologistify]

I'm glad I found this channel and I like your visual design with the dresses+background+animations

[@andreiparaschiv9915]

Finally someone who pronounces Einstein right

[@veteatomarporculo100]

Idk Noether was pronounced that way xd

[@inspiration1883]

@Hilmar Zonneveld I agree.

[@KarlBunker]

Meh. Correct pronunciation is relative to your frame of reference. 😁

[@andreiparaschiv9915]

@@KarlBunker My frame of reference is the way a German person would pronounce it, since you know, Einstein was German. I know that native English speakers have a habit of pronouncing everything, including foreign names, the way they find it comfortable (or consistent with their way of pronouncing stuff), but I don't think that's right. I think that we should try to pronounce names as close to the original pronounciation as possible. Obviously, it is impossible to get it right, but still, There's a huge difference between s and sh. It's not a matter of accent, they're totally different sounds. Imagine calling Lincoln ”Bincoln”.

[@rossmanmagnus]

russians also mispronounce the name by saying "en-sh-tain" instead of "ine-sh-tine"

[@KeithCooper-Albuquerque]

Great video Sabine! You make learning physics so much easier! Great outfit today as usual!

[@MarcSylex]

Sabine is like a scientist drill sergeant. She tears you down only to build you back up stronger in knowledge.

[@nourbielal9120]

I am a phd-student in mathematics, and I am very interessting in physics this dxplanation of the concept energy is the best explanation that I have ever heard. Danke schön Sabine.

[@drbill41]

Very well done and informative mini lecture. Regarding the red shift of light, has anyone calculated the correlation between the rate of expansion (if known with any degree of certainty) and the loss of energy due to the red shift through time and distance? Is there a numerical agreement between these quantities?

[@antonk.653]

Nice video, thank you. But I see, it's always difficult to explain energy. I'd like to add to it a small quote from my physics professor. He uses to say "Energy Gradient" instead of free energy. Wherever there is an energy gradient, you can tap it to do work. Perhaps it helps.

[@path7000]

If space is expanding (and space cannot be empty due to the cosmological constant) then that means energy is also expanding

[@antonk.653]

@@path7000 What has spacetime to do with free energy ?

[@MartinLeggewie]

Thank you very much for this precise and understandable explanation. Highly appreciated!

[@EarlWallaceNYC]

Excellent. I especially liked the distinction between "energy at low entropy" vs. "energy at high entropy". That was a revelation for me.

[@fluentpiffle]

All things are 'energy'. We currently call it 'space', and the reason it is conserved is because it exists infinitely, so it is always 'everywhere'. Essentially, it is 'that which exists', as its spherical wave-motions become the 'particle effect' we call 'matter', which are subsequently returned to a purely 'energetic' state with events such as 'black holes' .. "Commendation from NASA for research work at Massachusetts Institute of Technology on the Earth's atmosphere and the Moon's surface for navigation of the Apollo spacecraft to the Moon.. Dr. Milo Wolff has found the structure of the electron consisting of two spherical quantum waves, one moving radially outward and another moving radially inward. The center of the waves is the nominal location of the electron 'particle'. These waves extend infinitely, like charge force. All 'particle' waves mix and contribute to each other, thus all matter of the universe is interrelated by this intimate connection between the fundamental 'particles' and the universe. The natural laws are a direct consequence of this Wave Structure of Matter (WSM), thus WSM underlies all of science." spaceandmotion

[@venician2face]

Very well explained. As an engineer, I understood the "conservation of energy" but have always been confused by the loss of useful energy. This video clarifies it for me.

[@sebastianflad6072]

Yes, it is possible to explain what entropy is ... within 8 minutes. I was searching for such a good explanation for years. Thank you.

[@fekkezaum]

sabine, you are simply a genius. you make physics so understandable. i can't say this enough.

[@alwaysdisputin9930]

It was as clear as mud. No one understood wtf she was on about. Say we're experimenting with fart gas & our experiment gives the same results no matter what time you run it, thus it has "time translation invariance". We find the amount of fart gas is conserved. Therefore farts = energy because "Energy is then, by definition, the quantity that's conserved in a system with time translation invariance"

[@academicalisthenics]

Very fun to watch, thanks for your insightful explanations :)

[@lauocsap]

Thanks Sabine, I was always wondering where energy of light was going while shifting to red in the expanding universe. Really happy to have seen your video!

[@KhalilEstell]

Sabine uploads a new video, I stop what I'm doing, I watch and I thumbs up.

[@firstnamesurname6550]

Wrong, very likely, it must to be the reverse order .... First, You thumbs up and next, You watch ... If One watch it first and next thumbs up a Sabine's video ... A sensation of doing something wrong is very likely to merge ... Dude, A Sabine's video isn't a Ted's Talk video. With Sabine, Privilege Bias is Legal.

[@KhalilEstell]

@@firstnamesurname6550 Why are most of the people that reply to comments in this channel like this. Ugh. But yeah, I typically thumbs up first, watch and on rare occasions, I'll remove the thumbs up if I do not like the content, and even more rare, I'll thumbs down.

[@firstnamesurname6550]

@@KhalilEstell WOW, Had You Thumbs down a Sabine's video ??? 😱😂 Please, If You remember one of them ... copy and paste the links 👍

[@francisbosse3702]

Great as usual. Wow after two post doc, I finally have a better understanding of what is free energy. Thank you! 👍

[@despectable]

Thank you for these insights once again Sabine!

[@SteveJohnson-ls3et]

Really glad you mentioned Emmy Noether in this. Her theory feels very fundamental. I wonder if you could cover some of the other symmetries and conservation laws. I think your perspective may be helpful.

[@rodschmidt8952]

Pauli, I think it was, said that, just as time and space are fundamentally the same thing, so also energy and momentum are fundamentally the same thing (and in QM, energy is conjugate to time while momentum is conjugate to position, independently in each of the xyz directions); energy is the momentum that a thing has as it travels through time.

[@SteveJohnson-ls3et]

Sabine mentions Planck's constant as the missing ingredient for the maths to define the units, what is the missing ingredient for momentum and space?

[@hyperduality2838]

Symmetry is dual to conservation -- the duality of Noether's theorem. Energy is duality, duality is energy! Potential energy is dual to kinetic energy. Apples fall to the to ground because they are conserving duality. The conservation of duality (energy) is the 5th law of thermodynamics. Gravitation is equivalent or dual to acceleration -- Einstein's happiest thought, the principle of equivalence (duality). Electro is dual to magnetic -- Maxwell's equations. Photons, light or electro-magnetic energy is dual. Positive charge is dual to negative charge -- electric charge. North poles are dual to south poles -- magnetic fields. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. "Always two there are" -- Yoda. Energy is measured in Joules (Jewels) or duals! Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics. Teleological physics (syntropy) is dual to non-teleological physics (entropy) -- Shannon information theorem.

[@alwaysdisputin9930]

@@rodschmidt8952 _"energy is the momentum that a thing has as it travels through time."_ A photon has enough momentum to knock an electron away from metal (the photoelectric effect) but it's said photons don't travel through time because they see themselves as stationary & sees the universe moving at c & thus extremely slowed down due to time dilation. So how do u explain that?

[@Paul-ty1bv]

Thank you, Sabine. I've been wondering where the energy went in stretched electromagnetic waves.

[@david203]

It went nowhere. The universe simply expanded, so its volume is larger but the contents are the same.

[@fluentpiffle]

All things are 'energy'. We currently call it 'space', and the reason it is conserved is because it exists infinitely, so it is always 'everywhere'. Essentially, it is 'that which exists', as its spherical wave-motions become the 'particle effect' we call 'matter', which are subsequently returned to a purely 'energetic' state with events such as 'black holes' .. "Commendation from NASA for research work at Massachusetts Institute of Technology on the Earth's atmosphere and the Moon's surface for navigation of the Apollo spacecraft to the Moon.. Dr. Milo Wolff has found the structure of the electron consisting of two spherical quantum waves, one moving radially outward and another moving radially inward. The center of the waves is the nominal location of the electron 'particle'. These waves extend infinitely, like charge force. All 'particle' waves mix and contribute to each other, thus all matter of the universe is interrelated by this intimate connection between the fundamental 'particles' and the universe. The natural laws are a direct consequence of this Wave Structure of Matter (WSM), thus WSM underlies all of science." spaceandmotion

[@fuzzylumpkin8030]

Thanks it answered half of my question of the day🧐 funny thing is my research will involve energy at some point but right now it’s focused on time space and the transmission of information

[@fluentpiffle]

All things are 'energy'. We currently call it 'space', and the reason it is conserved is because it exists infinitely, so it is always 'everywhere'. Essentially, it is 'that which exists', as its spherical wave-motions become the 'particle effect' we call 'matter', which are subsequently returned to a purely 'energetic' state with events such as 'black holes' .. "Commendation from NASA for research work at Massachusetts Institute of Technology on the Earth's atmosphere and the Moon's surface for navigation of the Apollo spacecraft to the Moon.. Dr. Milo Wolff has found the structure of the electron consisting of two spherical quantum waves, one moving radially outward and another moving radially inward. The center of the waves is the nominal location of the electron 'particle'. These waves extend infinitely, like charge force. All 'particle' waves mix and contribute to each other, thus all matter of the universe is interrelated by this intimate connection between the fundamental 'particles' and the universe. The natural laws are a direct consequence of this Wave Structure of Matter (WSM), thus WSM underlies all of science." spaceandmotion

[@khananiel-joshuashimunov4561]

I had thought so for years now, glad to have some validation!

[@mikef4775]

“I hope you are now confused so we can explain this”😂😂

[@user-wu8yq1rb9t]

Hello Doctor. Doctor, I'm watching it (energy) now . But, Please make a video about Mass (what's Mass?) too. Thank you.

[@firstnamesurname6550]

Not Doctor, but it seems that Mass(es) is/are the topolog_y/ies where/when Energy converge in Itself in the singular branch and converge in an arbitrary point from a closed isomorph space in The plural branch .... In other words, Compressed Energy or Condensed Energy. Or just Dense Energy.

[@user-wu8yq1rb9t]

@@firstnamesurname6550 Thanks for your attention. Which things define when and where? And why? I know the higgs field and ...but I can't understand the essense of mass.

[@eljcd]

If I may, that's "easy": if E = mc², then m=E/c² Simple!

[@user-wu8yq1rb9t]

@@eljcd Thanks Juan. But ...... Nothing !!! If you mean just kinetic energy, it's not satisfing for me.

[@firstnamesurname6550]

@@user-wu8yq1rb9t Ups, but those answers are not in The Scope of Research for Physicists ... At that stage of questioning , We already are into "Metamathics" or Metaphysical Mathematics ... ... and those Metamathics will lead Us to Binary Compounds in an Eternal Present ... ... and That To Not-Time, Not Space ... .... and That To Non Existence ... .... and That To Non Answers .... ... The Higgs Field is a peripheral Harmonic from an Harmonic Serie of background of False Vacuums that must ends in an specular copy of a block universe from this Universe ....

[@AmaNotaGogo]

You are not only a clever lady. Putting together what you have just said here and what Richard Feinman said about being able to measure energy really got me thinking.

[@adramnauth]

Thank you! I also wondered about the implications of an expanding of the universe for concepts like conservation laws of energy (and maybe information?). I'm relieved my thoughts agree with what physicists are saying.

[@KibyNykraft]

Well it of course totally violates the conservation of energy (!) :) "Expanding" universe is basically just religion (creationism)/pseudoscience, the manic idea that everything had to be a universal start, a beginning from something (beginning in what ROFL, the whole concept is ridiculous), a magical arrow of linear/unrelative time "in" space and so forth

[@KibyNykraft]

Also see The great attractor evidence. An expanding universe by cosmic inflation would increase the entropy too fast, and it is anyway more or less debunked in detail, theorywise and mathematically, by many scholars. You will find that if they are mentioned in comment sections like these, the comments are removed/censored. that should warn about the state of affairs in academia (anti-skepticism)

[@fluentpiffle]

All things are 'energy'. We currently call it 'space', and the reason it is conserved is because it exists infinitely, so it is always 'everywhere'. Essentially, it is 'that which exists', as its spherical wave-motions become the 'particle effect' we call 'matter', which are subsequently returned to a purely 'energetic' state with events such as 'black holes' .. "Commendation from NASA for research work at Massachusetts Institute of Technology on the Earth's atmosphere and the Moon's surface for navigation of the Apollo spacecraft to the Moon.. Dr. Milo Wolff has found the structure of the electron consisting of two spherical quantum waves, one moving radially outward and another moving radially inward. The center of the waves is the nominal location of the electron 'particle'. These waves extend infinitely, like charge force. All 'particle' waves mix and contribute to each other, thus all matter of the universe is interrelated by this intimate connection between the fundamental 'particles' and the universe. The natural laws are a direct consequence of this Wave Structure of Matter (WSM), thus WSM underlies all of science." spaceandmotion

[@artyomfomenko2232]

Sabine: they mean the energy is free month end bill: 50$

[@designtechdk]

Energy is free sure, but converting it is not :)

[@ftcbrandt]

Some work has to be done to extract and make available all that coal. The same is true for the "free energy" content of batteries. It does require work to built batteries. And work costs money. Also, the english word "free" has two meanings ;-)

[@MrDino1953]

@@kensho123456 - Free, in this sense, means free or available to do work.

[@Psy0psAgent]

@@kensho123456 like a verb, ‘Free’ (the) energy, as in release it, Not free as in no cost.

[@kloassie]

Okay, but with the expansion of the universe that stretches the light I understand it increases the wavelength of that light (decreasing it's energy). But by stretching the light, doesn't it then also kinda increase the amount of that (lower wavelength-ed) light, thusly increasing the the amount of energy just as much as it decreased it? Consider an elastic string. When you stretch it, the string will get thinner (-> decreasing the amount of string per cm). However, the string will also get stretched as a whole, thereby creating more cm's of that thinned-down string. In total the thinning and the increase of length of the complete string balance each other out resulting in just the same amount of elastic string as what you started with

[@joansparky4439]

It's still just one photon.. or in other words, the model in your head of photons as electromagentic waves is insufficient to cover all phenomenons of those specimen.

[@scarrow]

I trust that if it behaved thus Sabine would mention it, but intuitively I thought the same thing. I would love to hear exactly why this isn’t the case. I kind of get that the individual photons are changing wavelengths and we’re not somehow magically spawning new particles to make up for the difference. Does this mean that we can think of this lost energy as driving the expansion of the universe?

[@kloassie]

@@joansparky4439 hmmm ... Sounds plausible in some way ... Still ... I need time to think about this ... [Edit:] While replying to the interesting comment of @scarrow I thought of some other possibilities 1. If the expansion would be a _consequence_ of the loss of energy, then the expanded state itself could be considered as a form of potential energy - same as when a ball rolls up the hill it looses speed (kenetic energy) but the whole situation gains potential energy. If all light has lost its energy, the universe might (theoretically at least) contract again, thus creating warmth/light/whatever-form-of-energy again 2. Dark energy is said to increase with the expansion of the universe, as the amount of dark energy per 3-/4-/multi-dimensional unit keeps the same during the expansion. The loss of energy in light then thus gets converted in a gain of dark energy In both situations I described the loss of energy in light results in a gain of energy in some other form. Now I have no clue how much that gain is (situation 2: according to the currently widely accepted theories) or might be (situation 1: @scarrows option), but my gut feeling tells me that the gain might just happen to balance out the loss -> resulting again in _not an absolute loss_ of energy

[@kloassie]

@@scarrow you mean the loss of energy could be not a consequence of the expansion, but that it might be the other way around: the expansion might just be a consequence of the loss of energy? Interesting thought!

[@FunkyDexter]

No, because waves don't work like elastic strings. Waves obey the equation speed of propagation = wavelenght * frequency. Since an electromagnetic wave travels at c in a vacuum and c is constant, a longer wavelenght must correspond to a lower frequency. In quantum mechanics, the planck-einstein relation thells you that the energy of a photon is equal to planck's constant * frequency, hence lower frequency = lower energy.

[@CharlieScarver]

My mind is blown. Now I have to research more on the topic 🤯 Super interesting video

[@diqweezle9751]

Thank. Your videos are so efficiently informative. I can't get enough!

[@rayzorrayzor9000]

My second comment now that I’ve actually watched the vid . WOW Sabine not only did you “nail it” for me you also answered a question that bothered me but I had never asked , you perfectly explained the effects of an expanding Universe causing the Redshift of light , and with that what about the change in energy ? I am now schooled , thanks again. Take Care . R .

[@SabineHossenfelder]

Happy you found it useful!

[@josephdestaubin7426]

You know, I am a blue-collar college dropout, but these videos make me so very happy! Edit: ok, now my brain hurts just a little bit. But it's ok, totally worth it.

[@kretieg2943]

I know all about NordVPN and use a VPN myself but listened to the entire segue just out of respect. That is how valuable your videos are.

[@jaypearce6743]

Thank you for including friction iin the energy equation.

[@vytautasdanielius7058]

Judging by my waistline during quarantine, I'm conserving tones of energy, just not the way I'd like.

[@gordianknot5625]

By now you must have enough potential energy to do tons of useful work.

[@UlaisisP]

Whenever someone calls me fat, I'll just say that I'm conserving free energy.

[@EK-gr9gd]

@@UlaisisP I am just isolating.

[@pekame]

"You just sit there .. and burn coal" this made me chuckle

[@vikramgupta2326]

This video took me back to my 1st semester of physics in college, at least the first part. But the second part about energy not conserved in an expanding universe --- new learning for me!! .... What is work? I remember that one from basic physics W = Force x Distance.

[@amyers2141]

Thank you, Sabine, for this one on conservation of energy. As a (now retired) university professor, I spent my career teaching the First Law of Thermodynamics, which states emphatically that energy is conserved. Therefore imagine my confusion when I read the reverse, that energy is not conserved in the Universe, according to the blog www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/ by Sean Carroll. You've got it exactly right: photons lose energy by shifting into the infrared. Energy is created when the Universe expands, which seems even more counter-intuitive. As it turns out, all is not lost, because on our little planet earth and throughout the Milky Way galaxy, the First Law of Thermodynamics is obeyed. The First Law breaks down only for the Universe as a whole, or for the chunk of the Universe that we are privileged to see.

[@rodschmidt8952]

Can we not say that if you wanted to compress "the Universe" then it would require energy, therefore energy is stored in Universe-size (or in space-curvature!) just as it would be in a spring? And therefore, when we add in that term, total energy IS conserved?

[@karlpoulin3938]

Sabine, you are simply the best ! Keep these videos coming, love. If you ever travel to Ottawa, Canada, drop me an email. It’d be real nice to meet you!

[@GlossRabban]

better than all the rest Better than anyone, anyone I ever met I'm stuck on your heart, I hang on every word you say Tear us apart, baby, I would rather be dead

[@derekfrost8991]

@@GlossRabban Tina turner.. :)

[@gilbertengler9064]

The same for me, when you drop by at the Cote Azur (do not worry, I am not french), please contact me for a deep discussion on interesting scientific topics.

[@derekfrost8991]

@@gilbertengler9064 I'm in France too.. :)

[@avinfor]

“Why save energy if physics say energy is conserved?” Someone has an adolescent at home.

[@TheAntonbacon]

Because i think what we realy mean is not conserving energy but saving money by useing less electricity. If everyone turnd off there lights for a day we would not have a saved pool of energy from that to use later. Makes me wounder if we set up a battery on our end to store the energy then used it to power our house if we would uses more or less energy from a direct feed from the grid.

[@paulgoogol2652]

Some things school doesn't teach you but bills do.

[@avinfor]

@@TheAntonbacon Well, think about it, if your source of energy has a price by consumption what you say only makes sense if that tariff changes, night tariff cheaper than day tariff for example, AND what you loose in your store-retrieval system (nothing is 100% efficient) still lefts some gaining in the process , AND the cost of the system (batteries and electronics) can be recovered by the savings in a reasonable amount of time. As of today that doesn’t happen so you don’t see products advertising this except “power-wall” like products but they target solar installations or unreliable grids not savings on a regular grid.

[@rebeccatripp36]

I could listen to your voice all day!

[@tenforce]

Great video, gives me, as a physicst, greater insights and better understanding

[@kalokajoe357]

One of those rare videos where at the end i say uffff, finally one that didn’t go against my understanding. Safe for now.

[@firstnamesurname6550]

If "understanding" is "your", then, that is not "understanding" ... When/where someone understand something that someone doesn't understand itself instead the other one ... Through a Time period, You understood Sabine's exposed understanding about The word Energy. ... and next, You wanted to take her merit as your merit ...

[@eddiegaltek]

I've long wonder what happened to the energy in a high energy X-Ray when it becomes a low energy microwave (as in the CMBR). I speculated whether it contributed to Dark Energy; not so much space stretching the wavelength of the photon as it passes through it but the wavelength of the photon expanding over time to stretch space.

[@arctic_haze]

I thought that maybe the electromagnetic energy E of the photon could be equal to the potential energy (towards infinity) caused by its mass (m=E/c^2). But it seems it is not. I need to check it out.

[@Boogaboioringale]

Since space is actually made of “something “, a photon has to “fight through it”. This would cause the photon to lose energy and thus have a longer wavelength. If space (or “spacetime “) can curve (gravity) and expand (dark energy) it must be “made” of something.

[@ps200306]

@@Boogaboioringale , what you're talking about is "tired light" (Google it), an idea that's been mostly discredited. If it was true then we'd expect to see frequency shifts in transparent materials such as optic fibres with a higher refractive index than the vacuum, and we don't.

[@eddiegaltek]

@@arctic_haze My thinking was maybe photons have a ground state like electrons in atoms. An electron in an atom wants to be at the lowest energy level and will emit photons to lose energy to get down to that lowest available energy level. Well maybe photons want to "Flat Line". To have an infinitely long wavelength with infinitely low energy. So as it is travelling through space the wavelength is slowly lengthening to get down to that lowest possible energy level; and in so doing stretching the space it's travelling through. Obviously if this idea had any merit some physicist would already have proved it.

[@Boogaboioringale]

ps200306: Yeah about that. In transparent materials, a photon hits an atom, knocks the electron to a higher energy level, then another one is emitted when it falls back down. I’m thinking space has much, much lower refractive index but who knows. I failed to mention the other thing. If space is indeed expanding, then the same amount of energy is simply spread over a longer distance so less energy per unit distance (even though we aren’t supposed to tell) or likewise longer wavelengths. Since we don’t expand as much as vast distances of space (70km/sec/per kiloparsec), it’s more noticeable for the photons than our detection devices.

[@js3883]

360 degrees is my head turning around and around listening to you. It is fun!

[@misteragb7558]

I appreciate how you cut right to the chase and dont waste my time with long pauses in between your sentences.

[@PlayTheMind]

About cosmological redshift: Is it possible that the energy lost is, in fact, some of the energy that was already given to the body that's moving away? After all, there must have been some energy invested in the fabric of spacetime in order for it to "gain momentum" to expand.

[@SabineHossenfelder]

You seem to be starting from the assumption that energy is conserved. Why?

[@PygmalionFaciebat]

I am curious what you say about my comment i just wrote in the commentar-section ?

[@terminator900000]

@@SabineHossenfelder I really enjoy the way you state things. Pure and calculated so there's no room for misunderstanding ^_^

[@PlayTheMind]

@@SabineHossenfelder To be clear, I'm okay with the conclusion that energy isn't conserved. On the other hand, I also think no stone should be left unturned, in case the thought expressed here is new. I'm just throwing the idea that there might be a link between cosmological redshift, and whatever it is that "pushes" the universe expand.

[@tissuepaper9962]

@@PlayTheMind As far as I understand, redshifted photons don't "lose" Energy, they simply never had a well defined Energy in the first place, because Energy is not defined for an expanding Universe.

[@HugeRademaker]

Everybody: switch off the light!

[@oisnowy5368]

And then jump all at the same time, long live potential energy!

[@firstnamesurname6550]

Thanks, for anticipating it before take the energy for making it noticed by the common spectators.

[@nziom]

Yes!

[@frankdimeglio8216]

THE THEORETICAL, SIMPLE, ULTIMATE, CLEAR, LINKED, BALANCED, AND EXTENSIVE MATHEMATICAL UNIFICATION OF PHYSICS/PHYSICAL EXPERIENCE IS PROVEN, AS E=MC2 IS F=MA: Very importantly, outer "space" involves full inertia; AND it is fully invisible AND black. Energy has/involves GRAVITY, AND ENERGY has/involves inertia/INERTIAL RESISTANCE. The perpetual motion of THE PLANETS in RELATION to WHAT IS THE SUN is the result of the fact that gravity/acceleration involves BALANCED inertia/INERTIAL RESISTANCE, as this IS proven by F=ma AND E=mc2. GREAT !!!! ACCORDINGLY, a given PLANET sweeps out equal areas in equal times; AS GRAVITY IS ELECTROMAGNETISM/ENERGY. THEREFORE, this NECESSARILY represents, involves, and describes what is MOTION AND NO MOTION IN BALANCE. SO, THE SPEED OF LIGHT (c) IS THEN understood as a POINT; AS the SPACE that envelopes THE EARTH IN BALANCE IS the MIDDLE DISTANCE in/of SPACE. E=mc2 IS F=ma, AS time DILATION ULTIMATELY proves that electromagnetism/ENERGY IS GRAVITY. (BALANCE and completeness go hand in hand.) Gravity IS ELECTROMAGNETISM/energy. Indeed, gravity AND ELECTROMAGNETISM/energy are linked AND BALANCED opposites; AS ELECTROMAGNETISM/energy is gravity. Again, E=mc2 IS F=ma. OVERLAY what is THE EYE in BALANCED RELATION to/with WHAT IS THE EARTH. NOW, LOOK at what is the translucent, semi-spherical, AND BLUE SKY. THE EARTH is ALSO blue. SO, objects fall at the SAME RATE (neglecting air resistance, of course); AS E=mc2 IS F=ma; AS electromagnetism/ENERGY IS GRAVITY. Great. Gravity IS ELECTROMAGNETISM/energy. ELECTROMAGNETISM/ENERGY IS GRAVITY. This is proven by F=ma AND E=mc2. Indeed, a PHOTON may be placed at the center of THE SUN (as a POINT, of course); as the reduction of SPACE is offset by (or BALANCED with) the SPEED OF LIGHT (c). GREAT. ELECTROMAGNETISM/energy IS gravity. This is proven by F=ma AND E=mc2. "Mass"/energy involves balanced inertia/inertial resistance consistent with/as what is BALANCED electromagnetic/gravitational force/energy, as electromagnetism/energy is gravity. Gravity AND electromagnetism/energy are linked AND balanced, as electromagnetism/ENERGY IS GRAVITY. ACCORDINGLY, gravity/acceleration involves balanced inertia/inertial resistance; as gravity IS ELECTROMAGNETISM/energy. The stars AND PLANETS are POINTS in the night sky. Objects fall at the SAME RATE (neglecting air resistance, of course), AS ELECTROMAGNETISM/energy is gravity. E=mc2 IS F=ma. Gravity IS ELECTROMAGNETISM/energy. Carefully consider what is THE EYE along with the falling man. "Mass"/ENERGY IS GRAVITY. ELECTROMAGNETISM/ENERGY IS GRAVITY. ELECTROMAGNETISM/ENERGY IS GRAVITY. This is proven by F=ma AND E=mc2. (E=mc2 is directly and FUNDAMENTALLY DERIVED FROM F=ma, as ELECTROMAGNETISM/ENERGY IS GRAVITY. That is where Einstein got it from.) This NECESSARILY represents, involves, AND describes what is possible/potential AND actual IN BALANCE. THOUGHTS are invisible. Very importantly, the ability of THOUGHT to DESCRIBE OR RECONFIGURE sensory experience is ULTIMATELY dependent upon the extent to which thought is SIMILAR to sensory experience. SO, BOTH equations apply to, represent, AND perfectly describe the MIDDLE DISTANCE in/of SPACE as invisible AND VISIBLE ELECTROMAGNETIC/GRAVITATIONAL SPACE in FUNDAMENTAL equilibrium AND BALANCE; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. The BALANCE of being AND EXPERIENCE is essential. "Mass"/ENERGY IS GRAVITY. ELECTROMAGNETISM/ENERGY IS GRAVITY. Consider THE MAN who is standing on WHAT IS the EARTH/GROUND. Touch AND feeling BLEND, AS ELECTROMAGNETISM/ENERGY IS GRAVITY. E=mc2 IS F=ma. Gravity IS ELECTROMAGNETISM/energy. It ALL CLEARLY makes perfect sense. Take careful notice of WHAT IS THE ORANGE SUN. Beautiful. Now, carefully consider the role and RELATIONAL significance of what is the eyelid. Consider what is lava. The viscosity of lava is BETWEEN that of what is water AND what is the Earth/ground. Gravity IS ELECTROMAGNETISM/energy. E=mc2 IS F=ma. ELECTROMAGNETISM/energy is gravity. Time DILATION ALSO ULTIMATELY proves that GRAVITY IS ELECTROMAGNETISM/ENERGY. E=mc2 IS F=ma. Indeed, this not only explains the term c4; but it ALSO explains the significance of the fourth spatial dimension. GREAT !!! Notice that THE DOME of a person's EYE may also be visible. THINK. IT IS CLEARLY PROVEN. "Mass"/ENERGY IS GRAVITY. ELECTROMAGNETISM/ENERGY IS GRAVITY. The stars AND PLANETS are POINTS in the night sky. INSTANTANEITY is thus FUNDAMENTAL to what is the FULL and proper understanding of physics/physical experience, AS ELECTROMAGNETISM/ENERGY IS GRAVITY. E=mc2 IS F=ma, AS gravity/acceleration involves BALANCED inertia/INERTIAL RESISTANCE; AS the rotation of WHAT IS THE MOON matches it's revolution. Moreover, objects fall at the SAME RATE (neglecting air resistance, of course); AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy. INSTANTANEITY is thus FUNDAMENTAL to what is the FULL and proper understanding of physics/physical experience, AS ELECTROMAGNETISM/energy is gravity. Ultimately and truly, time is NECESSARILY possible/potential AND actual IN BALANCE; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. (E=mc2 IS F=ma.) This NECESSARILY represents, INVOLVES, AND describes what is possible/potential AND actual IN BALANCE, AS ELECTROMAGNETISM/ENERGY IS GRAVITY. The INTEGRATED EXTENSIVENESS of thought (AND description) is improved in the truly superior mind. THINK. Gravity IS ELECTROMAGNETISM/energy. Time DILATION ULTIMATELY proves that electromagnetism/ENERGY IS GRAVITY, AS E=mc2 IS F=ma. The full distance in/of SPACE is thus LINKED and BALANCED with what is the middle distance in/of SPACE, AS ELECTROMAGNETISM/ENERGY IS GRAVITY. E=mc2 IS F=ma. GREAT !!!! The stars AND PLANETS are POINTS in the night sky. SO, stellar clustering ALSO proves that electromagnetism/ENERGY IS GRAVITY. Carefully consider what is A GALAXY. (BALANCE AND completeness go hand in hand.) By Frank DiMeglio

[@androkguz]

So much clarity. Thank you for this

[@exoplanet11]

Good topic for discussion. Most physics textbooks assume that energy is a strange concept and try to define it in terms of 'work'. But really 'work' is the strange concept, with many counterintuitive examples. If you define it the proper way, using an integral, you can get a consistent theory, but this is counter intuitive. I have noticed that actually my physics students find energy intuitive. So I use it to define work (as the difference in energy between two configurations ... eg ball on the table vs. ball on the floor). The exact value of energy is often arbitrary anyway. (Depending on where you define zero potential energy, or which reference frame you are in when defining kinetic energy.)

[@johnirby493]

Energy has a lot to do with time. The later in life one gets, the less energy one has.

[@xspotbox4400]

Not really, fit older person has more energy than lazy young one, also knowledge enable us to use technologies and became more efficient.

[@johnsmith1474]

You should take some "time" to check your prose for clunkiness.

[@hyperduality2838]

Energy is duality, duality is energy! Potential energy is dual to kinetic energy. Apples fall to the to ground because they are conserving duality. The conservation of duality (energy) is the 5th law of thermodynamics. Gravitation is equivalent or dual to acceleration -- Einstein's happiest thought, the principle of equivalence (duality). Electro is dual to magnetic -- Maxwell's equations. Photons, light or electro-magnetic energy is dual. Positive charge is dual to negative charge -- electric charge. North poles are dual to south poles -- magnetic fields. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. "Always two there are" -- Yoda. Energy is measured in Joules (Jewels) or duals! Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics. Teleological physics (syntropy) is dual to non-teleological physics (entropy) -- Shannon information theorem.

[@xspotbox4400]

@@hyperduality2838 Most dual thing i can think of is energy, things can move only because there's always a difference in interacting potentials. But that's it, only energy is dual, all other phenomena are just some concepts, don't need to come in pares or polarized.

[@hyperduality2838]

​@@xspotbox4400 Energy is duality, duality is energy. Potential energy is dual to kinetic energy -- gravitational energy is dual. Electro is dual to magnetic -- photons are dual, waves are dual to particles -- quantum duality. Watch the following video about the antinomies or dualities of Immanuel Kant:- kzbin.info/www/bejne/baqzoax6aNaXrpY Beginning (finite) is dual to eternal (infinite). Simplicity is dual to complexity, simple (elementary, atomic, holistic) is dual to composite (molecules, reductive). Freewill (randomness, entropy) is dual to order (deterministic, predictability, syntropy). God (thesis ) is dual to the Christ consciousness (anti-thesis) creates the holy spirit or the mind/soul. Thesis is dual to anti-thesis creates converging thesis or synthesis -- the time independent Hegelian dialectic. Hegel's cat:- Alive (thesis, being) is dual to not alive (anti-thesis, non being) -- Schrodinger's or Plato's cat. Being is dual to non being creates becoming -- Plato. In physics everything is made out of energy (duality)! Conceptualism (universals) is dual to nominalism (non universal) creates realism. Realism (reality) is synthesized by duality, duality creates reality! "Always two there are" -- Yoda.

[@eulefranz944]

So energy density is a small universe volume is still conserved in a broad sense?

[@SabineHossenfelder]

Yes, provided you are careful with defining "small".

[@CristalMediumBlue]

This is the best KZbin channel I have seen lately

[@walterblanc9708]

Its always important to learn things new, that's why I always click on Sabine's notifications!

[@PygmalionFaciebat]

8:10 ''Where does the energy go, it goes nowhere - it is just not conserved" I cant agree with that. Actually years ago i thought about this problem with the perspective ''why is dark energy called dark energy in the first place - when its just increases ''spacetime volume'' ?'' I had a conversation with a women, who helped me bring me to the idea : its dark energy because bigger space between masses means in the end: higher potential energy (gravitational energy) between the masses. And in that sense the lower frequency of every radiation which is affected by the expansion of the spacetime in the universe , correlates with a higher potential energy between the masses in the universe. Maybe i am wrong. If i am wrong, i dont know why i am wrong.

[@donnasummer6285]

“dark energy” is just a label...

[@PygmalionFaciebat]

@@donnasummer6285 I know. How , or on which part of my comment is your comment relating ?

[@davidgreenwitch]

What about the theory that the energy that "gets lost" is actually the dark energy that expands the universe? That would explain Dark Energy and save the conservation of energy!

[@Adrian.Rengle]

Right to the point .

[@MarkusAudio]

Second video, instant sub! Thanks for the lessons!

[@stankfaust814]

Thanks for such a great video explaining this subject. I think I could have used a 40 minute version.

[@sebastiankocaman7051]

Sabine has the only cool sounding german accent when speaking english I have heard or know of.

[@miffyn1737]

I found people with German accent when speaking in English sounds cute

[@anatomicallymodernhuman5175]

There is another but her topic is more niche. Look up Homay Schmitz.

[@samheasmanwhite]

I used to wonder why some people said that german people speaking english always sound angry but now I get it, it's funny how just a few tiny details and inflections can do that.

[@TheEulerID]

The continuity error at 3:42 when Sabine's hairline suddenly changes is a trifle abrupt. I wonder what the original was before it was re-cut and edited.

[@vj512]

I really like the rollercoaster example. Thumps up for a real life superconductiv magnets in vacuum model!

[@EagleSlightlyBetter]

love your presentations. thank you!

[@nabadjinha]

Coming soon, in a universe near you: Einstein Jones & The Raiders Of The Lost Energy Missing In Combat, starring Anti Matter

[@russchadwell]

"The ability to do work" always sounded like a dodge to me

[@DeusExAstra]

Yeah it's always been a circular definition, but it's because energy is just a very hard thing to explain. It's really a quantity in a system, but we treat is as a physical thing... like photons. We might say that a laser is an "energy weapon" because it shoots photons, and photons are pure energy. But really, any normal gun is an energy weapon since it shoots out chunks of fast moving matter which are energy (E = mc^2) and have kinetic energy (KE = 1/2mv^2) and do damage as a function of that energy. In any case, it's hard to explain what energy is in a simple sentence without resorting to something else most people understand, like work, even though to define work you need to invoke energy. It's like when Feynman was asked to explain magnetism, and he basically couldnt without getting into deep physics, he could not explain it in terms of anything a normal person would understand other than to say that magnets attract or repel each other, and that's a fundamental force.

[@rodschmidt8952]

I believe it comes from experiment. Lifting a weight, for example, is doing work. If you can make your thingie lift a weight, then your thingie is energy (and you can measure how much).

[@rodschmidt8952]

@@DeusExAstra I understood Feynman to say that magnetism is fundamental (it's just as fundamental as the electric force, in fact it IS the electric force viewed relativistically) and therefore there was nothing "underneath" it, to explain it in terms OF. In your phrase, there is nothing to resort to. I met him a couple of times, by the way

[@hyperduality2838]

Energy is duality, duality is energy! Potential energy is dual to kinetic energy. Apples fall to the to ground because they are conserving duality. The conservation of duality (energy) is the 5th law of thermodynamics. Gravitation is equivalent or dual to acceleration -- Einstein's happiest thought, the principle of equivalence (duality). Electro is dual to magnetic -- Maxwell's equations. Photons, light or electro-magnetic energy is dual. Positive charge is dual to negative charge -- electric charge. North poles are dual to south poles -- magnetic fields. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. "Always two there are" -- Yoda. Energy is measured in Joules (Jewels) or duals! Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics. Teleological physics (syntropy) is dual to non-teleological physics (entropy) -- Shannon information theorem.

[@colto2312]

I've always understood it as an imbalance within a system with a capture device between the potentials.

[@discoverrealityclover9620]

Awesome explanation of free energy and heat that I have ever heard!!

[@Turjak_art]

Danke Sabine. Du bist immer so schön angezogen, passend zum Hintergrund.

[@Elastane]

"why save energy if excess energy is conserved anyhow?" trolololol

[@UlaisisP]

Just like biologists have a hard time defining life, it's seems physicists have the same problem with energy

[@firstnamesurname6550]

The layers of abstraction for discerning and discriminate a sequential narrative of linguistic elements for describing to humans what they mean, the similarities and differences between the word Energy and the word Life is not a trivial issue ... While, The word Energy is a Concept that is used by some Humans for unifying and compressing everything in Itself into something absolutely homogeneous in abstract space ... The word Life is a Concept used by some Humans for assignment diverse human visual sense patterns, properties and faculties to an undefined quantity of diversified compounds of integrated elements exchanging diverse energetic dynamics inside a diversified energetic domain .... The word Energy is for Kindergarteners .... The Word Life for Old & Dead Post-Students ....

[@rv706]

I don't think so. What's wrong with the definition given by Sabine? Rather, I think physicists have a hard time defining causality (And no, I don't consider a suitable definition of causality one in which I am the cause of whatever lies in my future light cone)

[@firstnamesurname6550]

@@rv706 Is not "Energy" existence without Observers ??? Physicist just try to define that Observer independent "Homogeneous Essence" for a Single non local observer embedded by Itself and convoluted in Itself ... and next, by establishing a quantity as a threshold for differentiates the back and forth dynamics of the observer as a point in a topological space limited by the established quantity .... Sabine's definition is totally consistent with The Current Conception and Well established Theoretical Constructs operational functions on Their Respective Models in The discipline of Physics. Who is telling that Her definition is "wrong" ?? ( At least, not Me ) While Physics is a Quantitative and Mathematical Philosophical Branch ... On the other side of your analogy .... Biology is more a Taxonomy from Other Taxonomies ... Not yet a Philosophical Discipline or Philosophical Branch as Physics ... That taxonomies can use Statistics doesn't make them Philosophical Ontologies as Physics already is ....

[@Linshark]

Yea, I have problems every year in High-school. I can't use Sabine's explanation :-)

[@aniksamiurrahman6365]

Now Biology needs a Neother.

[@federicocamp2231]

Watching this reminded me of a bit done by a comedian named Brian Regan when he was explaining his experience watching a Carl Sagan episode on string theory. The opening line was: “I started watching at 8:00pm and at 8:03pm my brain exploded.

[@johnnisshansen]

Sabine is one of my favorits on KZbin. This talk about energy is one of her best.

[@hyperduality2838]

Energy is duality, duality is energy! Potential energy is dual to kinetic energy. Apples fall to the to ground because they are conserving duality. The conservation of duality (energy) is the 5th law of thermodynamics. Gravitation is equivalent or dual to acceleration -- Einstein's happiest thought, the principle of equivalence (duality). Electro is dual to magnetic -- Maxwell's equations. Photons, light or electro-magnetic energy is dual. Positive charge is dual to negative charge -- electric charge. North poles are dual to south poles -- magnetic fields. Energy is dual to mass -- Einstein. Dark energy is dual to dark matter. "Always two there are" -- Yoda. Energy is measured in Joules (Jewels) or duals! Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics. Teleological physics (syntropy) is dual to non-teleological physics (entropy) -- Shannon information theorem.

[@johnnisshansen]

@@hyperduality2838 , and pots are dual to crackpots.

[@hyperduality2838]

@@johnnisshansen Thesis is dual to anti-thesis creates converging thesis or synthesis -- the time independent Hegelian dialectic. Duality creates reality!