The Meaning of Energy? Core Physics Principle Explained by Parth G

Energy is an extremely important concept in all of physics. It is used everywhere to describe how different systems will behave. But what exactly is energy in the first place? What is the meaning of energy?
This difficult-to-answer question can be thought of in terms of a few different explanations. The one I prefer is that energy is a mathematical concept used to describe how different systems behave and phenomena occur. We can think of it as a mathematical quantity that we assign to anything relevant in what we are studying. Then, energy transfers (i.e. from one form to another, or from one place to another) occur in such a way that they obey the Law of Conservation of Energy. This allows us to predict how our system will behave over time.
Although we are talking about assigning energy values to different parts of our system, this does not mean we can randomly assign any energy values. These energy values are carefully calculated to be consistent with how everything around us seems to behave. An object with a specific mass moving at a certain speed, for example, will have a very specific value of kinetic energy based on its mass and speed.
Based on all experiments we've done so far, the Law of Conservation of Energy seems to hold extremely well. Therefore, we can use it to make predictions about energy transfers in our system, as well as how these will affect different parts of our system. And it's very interesting that the system can be very tiny, or it can be as large as our whole universe.
Another way to think about energy is that it is a physical property that objects have. For example, a moving car HAS kinetic energy (rather than the energy being a mathematically assigned quantity). This is a perfectly reasonable way to look at it, but if left unclear it can lead to some misconceptions. For example, it is easy to think based on this description that energy is some "stuff" that can flow from one object to another, almost like a fluid. And indeed, a long time ago scientists thought of heat (a form of energy flow) as a fluid. However energy itself is not a fluid, and does not have form in and of itself, like other "stuff" does. It can be thought of as "flowing" from one object to another, or transferring to a different type of energy (e.g. gravitational potential energy being transferred to kinetic energy as an object falls to Earth).
Finally, a common definition of energy is that it is the ability to do work (force x distance). But often, wordy definitions of work are stated in terms of energy. So this can lead to a circular argument, and if you are not fully comfortable with at least one of these terms then these definitions are of no help.
At the end of the day though, the reason the concept of energy is so useful is because of the conservation law. Energy cannot be created or destroyed, only transferred from one place to another, or from one type to another. It almost doesn't matter what energy is.
In this video, we also discuss how some forms of energy (e.g. potential energy) seem like a bit of a fudge to make the math work out. "Stored energy" that allows stuff to happen in the future, can easily seem like something's gone wrong. However this shows the problem with thinking about potential energy as "stored energy", or as "stuff". Additionally, all objects that we've ever studied so far seem to behave consistently with each other in terms of potential energy. The fact is, this energy value that we assign to objects exactly predicts how they will behave if a given amount of potential energy is lost - in all systems!
Some interesting reads (even though I don't agree with everything in them):
www.researchgate.net/publicat...
science.sciencemag.org/conten...
en.wikipedia.org/wiki/Energy
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Timestamps:
0:00 - Energy: A Very Central Concept to Physics
0:35 - A Useful Mathematical Concept to Assign to the System, and Making Predictions With It
1:47 - Can We Assign Any Random Energy Value?
2:54 - The Law of Conservation of Energy: Constant Total Energy
4:16 - Energy as a Property vs. Energy as a Mathematical Concept
4:48 - Misconceptions of Energy as "Stuff"
5:36 - Potential Energy: A Fudge?
7:30 - Energy as the Ability to Do Work
8:20 - Overview

[@girindrasinghrathore8418]

Parth's way of explaining concepts are always unique & different from others

[@altuber99_athlete]

That's a big statement. I really like The Science Asylum's way, too.

[@girindrasinghrathore8418]

it's relative

[@dhanashrikulkarni5878]

That is indeed a big one... I like Veratasium too!

[@varunmarar6771]

As long as the topic is nice and the explanation is good, there isn't a need to be the best.

[@TechnoEstate]

Things get weird/philosophical when you contemplate energy in terms of *_intention._* E.g.: a spring stores potential energy, because its atomic structure doesn't "want" to be compressed. Energy always works in tandem with forces: attraction and repulsion... i.e., showing an _intent._ See also Schopenhauer et al.: _the world as a will._

[@mazzky1093]

Thank you so much for this video! As a layperson this is one of those questions that never seems to get addressed. I don't think I've ever heard anyone say 'Its a mathematical concept'. This is the sort of explanation that helps me sleep better at night.

[@asdfniofanuiafabuiohui3977]

I think physists have this problem in that they'll have a model of how stuff works, which works well for calculations, but will then act like thats how things "actually are", and then this model will be taught in how things actually are, even if its not, so it creates a lot of confusion for the layman who ask "how does this work", which to the physists means "in what way can we model this to allow for predictions" but the layperson is asking "what is it, *really*?". I mean, gravitational potential energy works, but in reality gravity is due to accelerated spacetime, not potential energy

[@franciscodanieldiazgonzale2096]

Actually, I was taught Energy in this very same way, it is very common in a Physics degree: Newton’s laws are second derivatives and a pain, so let’s create a first derivative between the causes of the movement and the actual movement, a mathematical middle ground that helps by simplifying greatly the calculations: Energy!

[@_RIBOT_]

Aloha from Oahu! I’m a first year electrical engineer and I just wanted to say thank you so much for simplifying so many complicated topics! Before I started engineering I had been following your videos and your constant cheering and positive attitude towards being able to learn physics is one of the main reasons I gained enough confidence to study engineering so mahalo from the bottom of my heart 💙🌈

[@kikivoorburg]

Thank you!! About a year ago I fell into a rabbit hole trying to figure out what “energy” actually meant, and the result I came to was exactly what you described: a circular definition based on “work”. At that point I gave up searching, but now I’ve finally gotten a clear answer! Energy just being a mathematical concept which represents the consequences of the conservation of energy makes a lot of sense. It is just the best model we currently have to describe these particular object-to-object interactions. Whether or not it is a property (like mass) or something else is neither relevant to our understanding (yet?) nor known, which is why the definition ends up so confusing! Your channel is by far the best physics channel I’ve ever come across. You explain the most complex topics in simple, understandable ways, keep it up!

[@tehlaser]

The analogy that finally clicked with me is that energy is the currency the universe uses to balance its books (or that humans use to understand it, if you don't like to anthropomorphize). In the same way that money just sitting around may as well not exist, energy that isn't changing in some way doesn't matter. Both only have meaning when they can move. Energy and money are both useless numbers until they get transferred somewhere. The equations for various forms of energy (motion, heat, chemical, rest mass, whatever) are like prices or exchange rates. They tell you how to convert the currency. And like accounting, the universe follows double-entry bookkeeping. For every debit there is always a matching credit. The currency might look different, but the value is always the same.

[@deezynar]

That sounds better than most other definitions I've heard.

[@icanmakemusic362]

you're making the assumption that most people understand double-entry bookkeeping lol but I can see where you're coming from

[@johnboze]

My high school electronics teach said it the right way "WATT IS POWER" Q and A in the same line!

[@ali-om4uv]

You could shortly mention Noether's theorem and the fact that any conservation law is implied by a specific type of symmetry ?

[@TakesTwoToTango]

Was going to type a comment about this too. Noether's theorem is my favorite theorem in all of physics. I kind of understand why it wasn't in the video though... It's not linked to energy specifically, but to conservation laws as a whole. It changed my understanding of energy to THE conserved quantity in all systems that are invariant to time translation. I like the video though. Like for a struggling HS physics student, this type of explination could really help them make the concept click. I don't really like how energy is handled in a lot of HS level physics courses...

[@elaadt]

Great explanation for people with high school level physics at most. The concept of a number calculated and assigned to an object or system came across well. However, why this number should be conserved remained a bit "fudgy". You could mention Noether's theorem as a teaser for another video. This would give the viewer a sense that there is some solid science behind conservation laws without going into details here as it is beyond the scope of this video.

[@adibgbs3136]

what i found verrry useful to me, is understanding why the hell do physicists talk about work? why didnt they speak about energy, and that's all ! thank you parth

[@itsmeroky]

I think it is safe to say that no one knows what energy really is. - Richard Feynman (Feynman Lectures on Physics)

[@aniksamiurrahman6365]

Richard boy should be held accuntable for a lot of mysticism. "If you think you understand QM then you don't understand QM", An electron is a point particle, despite no one knows for sure, "no one kows what energy really is" despite the fact that Noether's theorem actually defines it very rigorously. In reality we can be modest and say we know this much and have no idea after that. The mystic BS only comes when we try to interpret in terms of day to day concepts.

[@alwaysdisputin9930]

@@aniksamiurrahman6365 Noether's definition of energy is deficient because it doesn't provide a mechanism for explaining why space is compressed near to energy. Is there something inside energy that is causing the spacetime to compress? Maybe but we don't know. Just because 2 things always occur together, doesn't mean that 1 causes the other.

[@aniksamiurrahman6365]

@@alwaysdisputin9930 "Noether's definition of energy is deficient because it doesn't provide a mechanism" Idiot man things everyone else is idiot cos he never bothered to learn anything.

[@MuharremGorkem]

I would expect a compare & contrast of energy versus other "concepts" (such as momentum, elasticity, conductivity, etc.) so that one can make a clear distinction of concept of energy and others that we also assign to physical objects or the world as a whole. Momentum is of particular interest. They both are concepts and have a common play ground. So, if we have one, why do we need the other? Are they inter-related? Is there anything else (beside the momentum) that is closely related with energy? How does this concept differs in Newtonian, relativistic and quantum mechanical system? Are the differences essential or pragmatic (computational etc.)? What about chemical energy? How on earth a charged battery behaves so similarly to a stretched spring? And the symmetries vs conservation laws... What is the symmetry that gives rise to conservation of energy? What about an expanding universe and conservation of energy? A very interesting aspect of energy is uncertainty principle expressed in terms of energy / time-interval... What does it tell us? Vacuum enrgy? Note that I am just a guy who is interested in popular science expecting a little bit more on the topic. I wish you try another take on the subject. regards,

[@En_theo]

You're right about the momentum vs. kinetic energy. There is a lot to explain there and most of physicists/engineers I talked with actually misunderstood the kinetic equation. It took me a lot of research to find out that Newton and Descartes actually disagreed with the fact that energy should be the square of the speed. It took 1 century of debate and experimenting to understand how it really works. Nowadays, this is taught in 10 minutes in universities and the real complexity behind it is ignored for some reasons, which explains why so many scientists were giving me confusing answers.

[@MuharremGorkem]

@@En_theo Very good points, thx for the reply. One of the things that I never forget about from my engineering education (EE) was in Physics 101 (or 102), where the professor used Taylor series expansion of the Einstein's famous equation only to find out that the fist term was Newtonian kinetic energy formula, and the rest of it was terms with higher order powers of c and v that can be ignored for small v cases! Perhaps they also deserve their own conceptualization :)

[@En_theo]

@@MuharremGorkem Yep, even in the famous Feynman's course (chapter 4), the v² of the kinetic equation is not even explained. He just says "it can be easily derived". Indeed, it's very easy to explain it mathematically but not theoretically. In practice, it's all about leverage.

[@randomblueguy]

Any discussion of what energy is should include Neother’s theorem.

[@thecoloroctet1365]

For me, the most intuitive definition of energy is the time component of the 4-momentum. It’s a more general/advanced definition, but I think it gives the intuition as to why both are constructed so similarly and both are conserved. Cheers!

[@LuisAldamiz]

That's interesting but wouldn't that be only kinetic energy, what about mass?

[@dinodubroja7433]

?

[@informationparadox387]

Can you explain it more clearly!🤠

[@alwaysdisputin9930]

@Redblue Please explain why you think energy is the time component of the 4-momentum vector

[@LuisAldamiz]

Good technical explanation but I think that what is energy does matter when, after all, we are defining nearly everything in terms of energy (gravity and the quantum forces/particles/fields most notably). Shouldn't understanding what energy is be the natural path for the betterment of physics? Maybe even for finding the ToE?

[@Cashman9111]

well, complex objects consist of simpler ones, there seems to be nothing simpler than energy so you cant really explain it, do you ? it's an axiom

[@LuisAldamiz]

@@Cashman9111 - I agree that energy seems fundamental but shrugging the problem off doesn't seem to me an option. It's like "a wizard made it", really, that's not the scientific approach but the "religious" one (i.e. "God made it", follwowed by the kid's next scientific question: "and who made God, mum?") Let's see: energy is constant for a given system, it can evolve from potential to kinetic and vice versa but does not change, however the ammount of energy of different systems or fundamental "objects" can be very different. Shouldn't we hope therefore for some quantization of energy as such fundamental underpinning of everything and thus at least attempt to unify all "particles" (wavicles) and "forces" into such "energy quanta"? I can see how this may well be a way to solve a lot of unncessary diversity in the Standard Model. Of course I don't know how exactly to do it (I'm not that smart nor well educated in all the intricacies of fundamental physics) but the first thing to slash out via this "energy quantization" concept should be the extra generations of matter, whose only difference is the ammount of energy/mass. However there is another issue: energy manifests itself in various fields (for example color charge, EM charge and mass/Higgs in the case of a quark), how do they relate to each other, because all those forces have in common to be energy, and if energy is so fundamental, they should be exchangeable somehow. My little two cents for your consideration anyhow.

[@TechnoEstate]

Things get weird/philosophical when you contemplate energy in terms of *_intention._* E.g.: a spring stores potential energy, because its atomic structure doesn't "want" to be compressed. Energy always works in tandem with forces: attraction and repulsion... i.e., showing an _intent._ See also Schopenhauer et al.: _the world as a will._

[@drdca8263]

I think this is taking a metaphor too far. We like to think of things having intent even if they don’t literally have an intent, because it makes it easy for us to think about, which, it is easy for us to think about things in terms of intent because we need to be able to easily think of the intent of other people. Other people is a large part of the world we live in.

[@TechnoEstate]

@@drdca8263 What is the difference between "literally" and "non-literally" having intent? If it is merely the complexity of the process -- e.g., immediate physical attraction/repulsion vs. physical attraction/repulsion through a longer chain of biochemical reactions -- exactly what's stopping us from regarding lower-complexity intent to be just as literal?

[@BryanBarcelo]

You are right, we need to be mindful of our choice of words we use to teach and describe also, we need to be mindful of the way that we tend project our human perceptions on to other things.

[@lorigulfnoldor2162]

@@TechnoEstate literal human intent can be frustrated - a human being can be disappointed with their intent unfullfilled. But energy, while "intending" to get to the lowest possible state, could still be perfectly resting in the local minimum for aeons of time with little worry or distress at all...!

[@TechnoEstate]

@@lorigulfnoldor2162 Great point. So in a way, non-human intent is *_more_* firm than human one. One could say: more _elemental,_ much the same way more complex nutrients like vitamins will easily be destroyed while it's much harder to destroy elemental nutrients like calcium (thus leading us back to Schopenhauer et al.) Even animal intent may prove harder/impossible to frustrate (e.g., instinctual/reflexive intent -- present in humans, too, though we do deny such the attribute of voluntarity).

[@LQhristian]

Great explanation! However, this description on energy is focused primarily on mechanical energy/systems. The law of conservation of energy behooves us to seek its higher/highest source!

[@malchicken]

I wondered while watching how energy relates to entropy. Is a higher entropy system the same amount of “energy” as a low entropy system? Or energy is also just a sort of “currency” to help with the accounting when changing from one state to another?

[@prashantlale4976]

Wow! Really acknowledged with parth Thank you so much

[@varunmarar6771]

Quality physics content, keep up the great work!

[@chrislong3938]

I'm late to this party but you've cleared up the one thing that has bugged me forever! There is no clear definition of what energy is! I've always wanted a clear definition but never found one. By simply acknowledging that in this video, I feel better and won't get hung up on something unnecessary and really trivial! Thanks!

[@zarchy55]

Great video. Thanks. If energy is not “stuff”, then how is energy radiated? What does it mean to radiate a mathematical definition?

[@jjaan]

Well when we speak about radiation it usually refers to light (or other forms of radioactivity). You then can assign this mathematical construct of energy to the electromagnetic fields that make up light

[@Jehannum2000]

Potential energy cannot be radiated.

[@thefran901]

Some particles in objects are turned into photons, those photons escaping are what we call radiation (at least in the case of infrared radiation). The photon itself is stuff, but we say the object loses energy by radiation because the photon that the object lost has a quantity of this mathematical concept we call energy assiged to it, and it's mainly expressed as part of the wavelength of the photon.

[@michaeledwardharris]

Very nice. I appreciate you attention to interesting and subtle details. I'm addicted to your vids.

[@stevenjones8575]

I think the elephant in the room for the layperson is: If potential energy is defined as the amount of kinetic energy that can be generated by a system, then duh, we've defined our way into a conserved quantity. When we define potential energy to be the amount of kinetic energy that can be produced, how is it any surprise that our potential energy ends up matching the kinetic energy our system can--but has not yet--produced? It's like defining potential potatoes as all the potatoes that will be grown but haven't yet grown. Potential potatoes + grown potatoes is then constant, making potatoes a conserved quantity, and yet not at all an insightful one. And so I appreciate the focus you put on energy being a mathematical tool. In contrast to the potato example, the way in which we've defined "energy" has led to great insights. So while it is a construct like the potato example, it's turned out to be a very, very useful one.

[@suyashpurwar631]

I loved it! I read this in Resnick Halliday too but it wasn't clearly explained there.

[@myothersoul1953]

Energy is a useful mathematical concept we can assign (aka measure) . Mass is a useful mathematical concept we can assign (aka measure) . Time is a useful mathematical concept we can assign (aka measure) . Length is a useful mathematical concept we can assign (aka measure) . And now you know all you need to know about what is.

[@icanmakemusic362]

I think the difference is in how we intuitively understand these things. I can easily grasp mass, time, and length. I can envision something in my head for all of those. not so with energy

[@schmuelinsky]

From my experience, it can be helpful to introduce physics concepts by comparing them to everday concepts. For example: Energy is like a currency that you gain or spend if you work with or against a force. Another example: Voltage is for electricity what water pressure is for a water pipe system.

[@anshumanchoudhary4732]

Great Vid ! Never stop making videos!

[@BytebroUK]

I'm impressed - you did all that without even mentioning "mc^2"!

[@bhavitarora4006]

Thank you so much for this. I'm preparing for JEE examination and just today I finished the work power energy chapter but still had doubts & this video cleared all of them

[@vijay_r_g]

So it's more like "shut up and calculate" when asked what it really means!

[@aniksamiurrahman6365]

Actually, if we go by Noether's theorem, enegy can be considered as a mathematical way to calculate the net change of a system due to a process.

[@alwaysdisputin9930]

​@@aniksamiurrahman6365 Near to energy, space time is curved. Why is spacetime curved near to "a mathematical way to calculate change"? No one knows. They just say "shut up & calculate" thus Vijay is correct

[@aniksamiurrahman6365]

​@@alwaysdisputin9930 Thanks for bringing this up. I just request you to read the whole comment, to the end. To find the answer, let's start with Einstein (again). After special relativity, Einstein set to figure out what happens when the reference frame itself is accelerating. From our day to day experience, we know that we receive a jark when our Car/Bus accelerates. But by relativity principle, every reference frame should be equivalent, there shouldn't be any physical way to tell apart, if a reference frame is acceleration, steadily moving, standing still. All of these supposed to be "relative". The answer came when Einstein imagined how a person in an accelerated reference frame will observe passing light rays. If a person is inside an accelerated frame - say while in a free fall, they'll see see that the passign light rays are getting bent. Since, light can't accelerate, so Einstein inferred that space-time itself appears bent with respect to an accelerated reference frame. Since an accelerated reference frame is equivalent to a reference frame with gravity (equivalence principle), thus Einstein inferred that gravity too causes space-time to be bent. So here we have it, right in front of us. There's no way to tell apart steady motion from stading still cos both preserves the symmetry of the space. Acceleration on the other hand is a "net change", a break in the symmetry. Since acceleration is equivalent to bent space-time, as shown in the paragraph above, we now can put 2 and 2 together and say that bent space-time too is a result of "net change".

[@aniksamiurrahman6365]

@@alwaysdisputin9930 TL;DR in GR, a frame with gravity is equivalent to an accelerating frame. And acceleration too is a "net change". And spce-time is curved with respect to an accelerated frame the same way its curved "near to energy".

[@alwaysdisputin9930]

​@@aniksamiurrahman6365 OK so you're saying acceleration is 1) a break in the symmetry 2) a "net change" 3) equivalent to bent space-time. This raises the question: why is there acceleration near to energy which is _"a mathematical way to calculate change"?_ IMO since there is no reason for there to be any acceleration, physicists can't rule out a supernatural explanation eg energy is the midichlorian space bugs. Vijay is right. I think we must be rotating & all gravity is in fact centrifugal force (described nicely in ScienceClic's recent video 'The Coriolis Force') As a side point, in his YT vid 'Einstein's Field Equations for Beginners!' the great DrPhysicsA seems to say the equivalence principle & acceleration is a type of symmetry rather than a "break in symmetry": _"The 1st is what is called the 'Principle of Equivalence' ..."_ |¯¯¯¯¯¯¯¯¯¯¯¯¯¯| |¯¯¯¯¯¯¯¯¯¯¯¯¯¯| | | | | | | ↑ g | | | | ⠀⠀⠀⠀ ⠀ | | | | | | |⠀⠀ 😕⠀ ⠀⠀ | ⠀⠀⠀⠀⠀⠀⠀ ⠀⠀ g ↓ |⠀ 😕⠀⠀⠀ | | |¯| | | |¯| | | /| |\ | | /| |\ | | / \ | | / \ | |____/___\_____| |____/___\_____| |_______________| ________|______________|________ _... & what that says is that: if you are in a box with no windows, then you cannot tell the difference between being in outer space & accelerating with an acceleration, g or being in the same box on the surface of the Earth - stationary but subject to that gravitational force which carries an acceleration: g "_ |¯¯¯¯¯¯¯¯¯¯¯¯¯¯| | | |¯¯¯¯¯¯¯¯¯¯¯¯¯¯| | | | | | | /\ |¯¯¯¯¯¯¯¯¯¯¯¯¯¯| | | | | |¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯| g / \ | | | | | | | | ¯||¯ | | | | | | | | || | | | | | | | | || | | | | | | | | ⠀ ¯⠀ |........................| |.......................| |........................| 👉 |_ _ | | | | | |______________|⠀⠀⠀⠀⠀ | ' - . | | | | | | ⠀⠀ ' -. | | | |______________| | '-. | | | | '| 👈 |______________| |_______________| _"...& if this box is accelerating with an acceleration: g ...... by the time the light gets halfway across, the box will have accelerated a little bit further forward, so it'll now be here. ... By the time the light gets to the righthand side, the box will, of course, have accelerated still further & now the light, (which, of course, is just going in a straight line), will reach _*_here._*_ In other words, the overall impression is: that the light has gone from here to here to here & that's a curve. At least it should be if I've drawn it properly. So Einstein says: if that is what happens when you are accelerating through space with acceleration: g since the principle of equivalence says you can't tell the difference between that & being stationary on Earth subject to an acceleration: g then the same thing should happen in _*_this_*_ scenario here: that light will appear to bend in a gravitational field."_

[@smedentsev]

I can't believe that 112 years after "Materialism and Empirio-criticism" was written we are still coming back to this discussion and separating "energy" from "matter" when ANY scientist considering himself a materialist (as he obviously should) should know from the elementary school that energy=matter, where matter is taken in both gnoseological (epistemological) and ontological definitions as the objective reality existing prior to and independently from consciousness (where consciousness is taken in the broadest term possible, opposite to matter) and reflected by latter. And as such it is 1) infinite & 2) indestructible and eternal. This not only immediately gives the strict definition of energy and provides a direct grounding for the law of conservation of energy by clearly debunks all and any philosophical idealism and dualism parts of which we clearly see through this video. The separation of matter into "matter" (in the layman terms but actually "mass" in scientific terms) and "energy" breaks the fundamental unity of nature. It is a a very useful assumption to separate all matter into two entities called "M" ("mass") and "E" ("energy"), such as made be Einstein in his M=E/c2 but we should never forget that from the other prospective his formula does not simply separate E from M but at the same time unites it as being inseparable and interdependent. Matter is indestructible and for any "loss" of mass the corresponding proportional amount of energy is "created" and vice versa so the overall amount of matter (which we earlier split into "M" and "E") remains constant. Mass ("matter" as "stuff" as most people perceive it) and energy are simply the properties (attributes) of matter (just as time and space) and are never "lost" or "created", but rather simply transferred in some form with overall total sum being constant. Energy exists only as the opposite for mass, as a separation required for human reflection and understanding of matter. It is neither a mystery nor a philosophical (or physical) hodgepodge nor simple mathematical assumption.

[@aaronnorman9755]

That’s a very good point, however energy-mass equivalence, E=mc^2, can only be applied if a particle is stationary, meaning that you can no longer use it if the particle is moving, this is because the particle gains mass as it’s velocity increases, which is why the mass denoted in E=mc^2, is the particles rest mass. Another thing is that you can not use it with massless particles, like photons. If you think about it, a photon certainly has energy, but does not have mass, therefore if we used E=mc^2, it would say that it has no energy, which is clearly not true.

[@smedentsev]

@@aaronnorman9755 Excellent point and correction. I've indeed oversimplified the situation to fit it in the comment format. The full story of course is a bit more complex but not too much :) And although both relativistic affects and massless particles were well known even back n 1909, the whole "energy" story has stirred way too much controversy not only among "philosophers" but physicists too. And it still echoes in 2021! :)

[@aaronnorman9755]

@@smedentsev I think I understand what you mean now, I apologize, it seems that I misunderstood the full idea of your argument. So would it be correct to say that what you meant initially is that, the overall focus has been lost?

[@smedentsev]

@@aaronnorman9755 Well, may be. Depending on what do you mean by lost focus as I can easily misinterpret your words :) But basically yes. With all due respect to Parth (I've learned quite a lot from his channel and think it's great) the whole video doesn't come anywhere close to answering the question "what is energy". Instead it just confuses people in almost exactly the same way it was done 100+ years ago. But c'mon - it's 2021. I think contemporary scientist should be able to do it better now.

[@justarandomguywithsuperpow6146]

awesome video but i have a question , i also know that energy is a mathematical concept , and when a car moves we assign it a form of energy known as kinetic energy which is 1/2 mv^2 and u made it quite clear in the beginning but where did the eqn come from , how was it formulated and why kinetic energy "IS" equal to that specific value ?

[@shaiavraham2910]

It's a bit mathematically involved, but the basic idea is that if you integrate force with respect to displacement (which is the definition of work) with Newton's second law, you get that the work equals the difference of this value mv^2 / 2 between two velocities. So, it was convenient to assign the term mv^2 / 2 to kinetic energy. It's also mathematically convenient because if we differentiate the kinetic energy with respect to velocity, we get the definition of linear momentom.

[@alwaysdisputin9930]

Ben Ryder's YT vid 'Kinetic energy derivation' explains it well. F = ma , a = v/t , d = ½vt & work done = F times distance => work done = ma x ½vt = mv/t x ½vt = ½mv² A train moves with constant velocity v Let's make a graph! Graphs are FUCKING AWESOME v ↑ 60 |_______________ distance, d = vt Now imagine the train accelerates from 0 to 60 kmhᐨ¹ v ↑ 60 | | ╱ | | ╱ | | ╱ | | ╱ | |---------------------|-------> 10 t Now the area under the graph is half what it was before. Therefore d = 300 km => d = ½vt The train has accelerated to 0 to 60 km in 10 h Therefore the acceleration, a = an increase of 6 every hour = 6 kmhᐨ¹ every hour = 6 kmhᐨ² => a = v/t Newton said F = ma _"& verily I say unto thee that the powerfully a man farts, the more force is generated & the more quickly his gas accelerates through the room in a most ghastly manner"_ & if you are using farts to propel a train, then a continuous stream of forceful farts for 60 km is going to create a lot of energy, whereas if you only fart for 1 m then less energy has been emitted from your anus Thus energy = Force x distance & then you just throw everything into a bowl & mix it all together & ½mv² comes out Where does the ½ come from? from d = ½vt. It's because the object has been accelerated not going at constant speed Where does the m come from? from F = ma Where does the v² come from? 1 v comes from the distance the object travels: d = ½vt 1 v comes from the rate at which it accelerates, a = v/t i dunno why we multiply the 2 v together. Maybe you can see why? Objection: A train with constant velocity is not accelerating yet it still has KE = ½mv² Yes but it had to be accelerated to reach that velocity. Energy was used to get the train to that velocity.

[@theartofmusic05]

Nice explanation Parth

[@EngGear]

This is a great video. thanks a lot.

[@magicalworld5446]

Do energies transform with the help of forces? What's the work done by dark energy in expanding the universe?

[@miraculousbtsarmy4430]

Hi I was wondering whether it’s possible that energy is an another dimension like time is. If you think of time being a number or represented by a number isn’t energy kinda similar?

[@ailblentyn]

I used to think that potential energy was a fudge, in contrast to "real" (kinetic) energy. But mow I think I understand that you can actually see kinetic energy itself as a potential: it's the potential to do work. So kinetic energy too is a mathematical fiction, as Parth says. But a useful one!

[@Ottmar555]

In continuum mechanics when you really get into the deformation of materials, you get to understand what the potential energy of a spring is, and it's quite complicated and technical. Fun stuff.

[@ahmadnabeelnajeeb6101]

Hey Parth, I have had this doubt fit a while now, what is the difference between 'magnetic field intendity' , magnetic flux density' , 'magnetic susceptibility' etc etc. It would be a pleasure to watch u explaining these concept.

[@alexb241]

So I have a question regarding potential energy that I hope is not too much for this context: I know that due to E=mc² a compressed spring has more mass than a relaxed one. How does that translate to the potential energy in a gravitational field? The ball that is following a curved space-time-path in freefall surely does not gain mass? So does an object that is held by something, perhaps the surface of the earth have more mass? And then loses this mass as soon as it starts to fall? Thank you in advance!

[@fadhilshiddiq2231]

I use to think of energy as a mathematical concept, but when I learn about quantum its feel like energy is a "stuff"

[@vaishnavchandra5220]

I had been pondering around this fundamental concept since quite a while. This was really an helpful video....Thanks

[@yashdadhwal3034]

Well for me energy seems to be a fundamental quantity required for existence itself it is needed for existence or motion in spacetime and when you set the whole energy as zero that object just disappear

[@fritt_wastaken]

Energy most definitely is not fundamental. It's just a useful number that we can calculate for a given system. Fundamental are the rules at which constituents of that system interact, and properties like energy, momentum, temperature etc are just useful mathematical concepts that emerge from these rules. Like, you can theorytise the game of chess by assigning some useful values to pieces and to board states, but that wouldn't make those numbers fundamental to the game.

[@yashdadhwal3034]

@@fritt_wastaken yeah but just imagine is there any thing in this universe which can exist without energy when we set total energy content of a body to zero it just cease to exist like if something is there it should have non zero energy

[@yashdadhwal3034]

Things can still exist without other properties like momentum temperature but energy seems to be always there

[@Skellborn]

I'm somewhat confused as to how to think of it still. I always have. It seems like an abstract concept, that is really useful and not something that is a property of an object, but then there is the energy-mass-equivalence, which somehwat implies it is something more "real". Could you maybe elaborate more on this? :) Thank you so much

[@schmetterling4477]

What is abstract about "energy is the ability of a physical system to perform work on another physical system" definition? Mechanical work is anything but abstract. If you don't believe me, run up and down the stairs ten times. That is work. Your ability to run up and down the stairs, at all, is fueled by chemical energy. Stop breathing for ten minutes and there won't be any more running for you. :-)

[@aravindkamble4558]

Please make a video on Free energy concept

[@gowrissshanker9109]

Respected sir, like Lorentz force caused due Relativistic effect, IS the INDUCED EMF by changing magnetic flux is also an RELATIVISTIC EFFECT!?? Can you please explain how INDUCED EMF IS PRODUCED...

[@tommyhuffman7499]

Love this video! Thanks!

[@ray_7594]

Who thought of some quantity like energy ?? Please make a video on how energy was thought initially and how changes in definition occurred (if any)

[@Gwunderi25]

This would be very interesting indeed.

[@tomkerruish2982]

Could we use general relativity to define energy in terms of curvature via G = 8 pi T?

[@kenlogsdon7095]

Yup.

[@alwaysdisputin9930]

No one knows why spacetime is curved around energy so your definition of energy would be like "energy is a thing that somehow spacetime bends near to it possibly due to wizard magic but energy might instead be midichlorian space bugs"

[@kenlogsdon7095]

@@alwaysdisputin9930 Fun fact: If spacetime didn't "curve", there could be no such thing as energy of QM matter.

[@alwaysdisputin9930]

@@kenlogsdon7095 why do you say that?

[@kenlogsdon7095]

@@alwaysdisputin9930 Start here: kzbin.info/www/bejne/oIqon3lrfc-Ni5Y

[@LynxBlackWind]

It's a good explanation, but if energy is not any physical stuff, but abstract quantity, then why do we say that universe consists of about 70% of dark math concept, next to ~30% of dark and regular physical stuff?

[@saudyassin5352]

That's what i call a great question; i think the answer might be that dark energy isn't a physical entity that fills our 4 dimensional space-time, but a rather a mathematical quantity assigned to the so called dark matter. As an example: if we have a hypothetical dark matter moving car then we can say it have 0.5*mv dark kinetic energy (whatever that suppose to mean). Overall, i still think we are inconsistent in our definition of dark energy, for instance if dark energy is the energy assigned to dark matter then that energy is responsible to accelerating regular matter ( galaxies and so on), so dark energy cause change to regular matter as well which means it isn't specifically limited to dark matter. At the end of the day this just my opinion as a science student.

[@gangadharabarik9479]

Awesome ❤️👍👍👍👍❤️❤️ explanations 💯💯👌🌈

[@sMeLLwAtER]

Would the word be interchangable with information?

[@amankumardwivedi4139]

Thats accent with an indian glad to here and alos the concept is very great

[@Kaleidoscopeinme]

Thankyou for this !💪

[@kenlogsdon7095]

Fun fact: Without spacetime curvature there could be no energy of matter (per the Einstein Field Equations). No mention of this here, however. Oh, well...

[@onepieceatatime]

A compressed (or stretched) spring has potential energy, and therefore additional mass, and that small amount of mass can be measured in a lab on very sensitive scales.

[@Kaleidoscopeinme]

Explains the reason why I never understood the potential energy

[@wizardofboz76]

Does this imply that we really have no idea what energy is? Examples of energy 'flow' I struggle with are more in the thermal sense -> for some reason it feels intuitive for energy to heat things up... but what in the world is going on in the refrigeration cycle and the expansion of gasses? or Peltier coolers for that matter?

[@valentinmalinov8424]

The explanation of what Energy is you can find in my book only - "Theory of Everything in Physics and The Universe"

[@alianjohnson6035]

excellent thanks man

[@lifeofphyraprun7601]

I really liked it that you addressed the fact that energy is misunderstood to be like a thing that is stored in objects.I mean,it's fine to consider it as a property,but why consider it as a thing?People use phrases like,'made up of energy' for some physics sounding stuff(I am being vague,because I remember having heard similar phrases, but don't remember where).But to me at least,that kind of a statement doesn't make sense.Also,if it wasn't for potential energy then we wouldn't be able to treat even the simplest of systems in elementary physics as systems and would always have to calculate work done on each component. Why put in that extra effort,when you could just get a sense of a property that just depends on the configuration/arrangement of the system(perhaps the simple block,spring,Earth(everything ideal) system) ?The property being potential energy.So yeah,potential energy should make sense.😅

[@ajaynongmaithem4330]

Since the light in the ergosphere keep on rotating, we wud we be able see that?

[@ChannelSRL1]

Perhaps Parth or his subscribers can clear up some confusion for me: I have read that a photon is a 'packet of energy' but I have also read that photons can have different energies. What then is a "packet" if the values can be different?

[@Sparky-vj2dq]

This was very good if slightly unsatisfying as some others have suggested. To understand energy further you have to look at extreme situations such as the end of the universe (possibly cold, dark with no energy) or my favourite at the other end, the Big Bang (wasn't either big or a bang). Because stuff basically falls apart or melts with increasing temperature, the earliest recognisable "stuff" in the universe is thought to have been a quark-gluon plasma. I'd love to hear some speculations as to what that came from. Is there wiggle-room in E=MC^2 to allow the origin of the universe to have been a stupendously large value of potential energy?

[@MrVladanbajic]

Does anybody explain energy conservation in parapsychology? Like material things that vanish?

[@dinodubroja7433]

Energy is magical mist that flows from object to an object and gives universe its glow. But more scientificly: Energy is property of the universe, in order to make a change you need energy. But what is "change". Actually it all comes down to position and velocity. In oreder to change something in universe you can do 2 things. First: place things away from their equlibrium point. For example, spring reallllyy loves its equlibrium point and it will do what it can to stay there. So in order to strech or compress spring you need to give energy (do work) and pull the spring applying force that overcomes elastic force of the spring over a certain distance. Force × distance=lost energy. So if you want to put things away from "where they should be" you need to give energy. Another thing you can change in universe is somethings velocity. If you exert a force on an object you will change its speed over time. (Force applied)×(The distance force whas applied on)=lost energy. Its allways force×distance

[@RosaLichtenstein01]

So, energy is a 'useful fiction' -- like the crystalline spheres of Ptolemaic astronomy --, or it's a mathematic device, like the epicycles, also of Ptolemy's theory? But if it's a fiction, or even just a mathematical device (like, say, the centre of mass of a galaxy), it doesn't actually exist, so what is it doing in a discipline, Physics, that attempts to explain the universe in _physical_ terms? If matter is energy, then is matter too just a useful fiction? And what exactly is conserved if it doesn't actually exist? In the car example near the beginning, we are told that energy is "transferred to its surroundings". But if energy is just a useful mathematical device that enables us to predict certain things, then nothing is actually transferred -- no more than when we add 4 to 3 to obtain 7 the first two numbers are 'transferred" into that 7. So, it seems that energy works in modern physics like the angels who pushed the planets around in their orbits; they too were mysterious entities that allowed astronomers to predict with increasing accuracy over the years the position of the planets. Energy or angels, take your pick. Neither ends up as a physical explanation of anything. Physicists who then say they don't care what energy is, it is just a useful concept, have in fact _given up being physicists_ and have become tellers of tall tales, like those who believe in angels.

[@sphaera2520]

I think you’re missing the forest for the trees…or is the saying the other way around? Regardless, pretty much all of physics is made up of human invented concepts we use to describe the reality we observe. They’re not actual reality in and of themselves. Is an electron really this point particle, like a little marble, or is it a wavefunction with various characteristics? Well, both descriptions have useful explanatory power and so humans have found it convenient to utilize such descriptions even though what an electron really truly is, is neither of those things. Which are just convenient human concepts we’ve assigned to phenomena so we can talk about them and use math to make predictions. At least that’s my opinion and I think others share it as well. Sabine hoff…something (I struggle to remember the german last name) has a video where she kind of describes a similar thing. What does it mean for something to exist? In the end, iirc she says something can be thought of existing if it is a necessary component in order for us to successfully describe reality/make predictions. Luminiferous aether doesn’t exist in that sense because it is currently a superfluous (at best) concept that doesn’t really change our descriptions if we include it or not. Whereas (at least for now) spacetime is very necessary in order to make accurate predictions and thus we can believe that spacetime is real. Again, at least that’s my takeaway.

[@RosaLichtenstein01]

@@sphaera2520 "Regardless, pretty much all of physics is made up of human invented concepts we use to describe the reality we observe. They’re not actual reality in and of themselves." That implies there are no atoms, light waves or forces. That can't be correct. I have also taken Sabine Hossenfelder to task over that opinion hers, here: kzbin.info/www/bejne/eYXToWN7eM13mKs Check out my comments below this PBS video on KZbin: kzbin.info/www/bejne/lXmXqaWMr8lpa7M I repeat: "So, it seems that energy works in modern physics like the angels who pushed the planets around in their orbits; they too were mysterious entities that allowed astronomers to predict with increasing accuracy over the years the position of the planets. Energy or angels, take your pick. Neither ends up as a physical explanation of anything. Physicists who then say they don't care what energy is, it is just a useful concept, have in fact given up being physicists and have become tellers of tall tales, like those who believe in angels."

[@sphaera2520]

@@RosaLichtenstein01 I had a really long comment that was starting to turn into a book. Heck, even the tldr is still a wall of text. This is a part of that tldr which tries to encapsulate what I was trying to communicate. Tl;dr Instead of “there are no atoms and forces,” it’s that “atom” and “force” are the words/framework/invention of an intelligent mind to express/describe a collection of its perceptions in a way that is intuitive to itself and consistent with the reality that it can observe. As we gaze deeper at the source of these perceptions (presumably getting closer to the true nature of reality), beyond a certain scope these initial conceptualizations can break down and cease to be useful or lose their meaning, and so we adopt different terms and ideas that are more appropriate at that level*. This cycle encapsulates the nature and limitations of these concepts as human ideas that express how we perceive the thing (phenomena), which can change with greater perception, and are not the actual thing in and of itself (noumena)*. Circling back to the original point, does the fundamental thing we perceive and describe as “atom” and “force” exist? Personally, yes. The distinction that every word is a product of the human mind is uninteresting to be always referencing, after all everything we could ever talk about uses a made up human idea/word. So it’s more useful to reframe what it means for the thing a word conveys to exist by understanding it in the way sabine talked about. Which is why if I were to be extremely pedantic I would conclude forces are emergent large scale approximations of a real thing because that thing is necessary to describe true aspects our shared reality. The uninteresting answer would be no, [insert any word] is a human construct to describe a collection of perceptions we share as a means to facilitate communication and creating useful frameworks that allow us to make accurate predictions and the only thing that exists is my perception of reality. *these are rabbit hole topics that I truncated to keep the post short-er.

[@RosaLichtenstein01]

@@sphaera2520 Thanks or that, Sphaera: "'there are no atoms and forces,' it’s that 'atom' and 'force' are the words/framework/invention of an intelligent mind to express/describe a collection of its perceptions in a way that is intuitive to itself and consistent with the reality that it can observe. As we gaze deeper at the source of these perceptions (presumably getting closer to the true nature of reality), beyond a certain scope these initial conceptualizations can break down and cease to be useful or lose their meaning, and so we adopt different terms and ideas that are more appropriate at that level*. This cycle encapsulates the nature and limitations of these concepts as human ideas that express how we perceive the thing (phenomena), which can change with greater perception, and are not the actual thing in and of itself (noumena)*." But on that account there is no 'true nature of reality'; all you have are these 'perceptions'. This is just old fashioned Subjective Idealism. And Kant, another Idealist, was hopelessly confused about these 'Noumena'. Labelling a total mystery, 'Noumena', is no more use than calling it 'Susan'. A new name does not make it any less of a mystery. "Circling back to the original point, does the fundamental thing we perceive and describe as “atom” and “force” exist? Personally, yes. The distinction that every word is a product of the human mind is uninteresting to be always referencing, after all everything we could ever talk about uses a made up human idea/word. So it’s more useful to reframe what it means for the thing a word conveys to exist by understanding it in the way sabine talked about. Which is why if I were to be extremely pedantic I would conclude forces are emergent large scale approximations of a real thing because that thing is necessary to describe true aspects our shared reality. The uninteresting answer would be no, [insert any word] is a human construct to describe a collection of perceptions we share as a means to facilitate communication and creating useful frameworks that allow us to make accurate predictions and the only thing that exists is my perception of reality." Ok, well that is a slight improvement on what you said before, but I found it rather vague -- and then you ruin it all by re-introducing all those 'perceptions'. Once again: 'electrons' now appear to be 'useful fictions', necessary to make sense of these 'perceptions', not genuinely existing 'particles'/'waves' in their own right. You won't find a single scientist working in, say, High Energy Physics, mention his or her 'perceptions' when modifying a given theory, or constructing a new one. They might do so as they attempt to dream up some amateur metaphysics -- a bit like you and Sabine, in fact -- when they try to 'popularise' their ideas (for instance, here on KZbin, in mass circulation paperbacks or in the New Scientist/Scientific American) --, but not in the technical papers they publish in academic journals.

[@drdca8263]

@@RosaLichtenstein01 Perhaps a structuralist view of mathematics could be applicable here, as justification for saying that physical things “are” mathematical objects. Like, we talk about groups and topological spaces etc. etc. as being “the same” when they are isomorphic. Then, if we have an exact correspondence between something which we have admitted as “being truly physical” (such as, say, positions and lengths in spacetime) and a mathematical structure, we can identify the two (and say that spacetime “is” a differential manifold, with a given metric, for instance). (In the same way that the groups and are “the same group”). In this case, if we, in addition, grant that “the collection of all possible configurations of these physical things, including positions, momenta, etc.” is a “physical” notion, well, then we could argue that this collection “is” a symplectic manifold, and then, using this setting, applying Noether’s theorem, we get, associated with time translation symmetry, a quantity which is unique up to a multiplicative constant, associated with each configuration, and is locally conserved. Then, because the symplectic manifold and such “are” the actual physical things, perhaps by the same virtue, the energy should also be said to be a “physical” thing. I have thought that a nice variation on Planck units would be to use, instead of fundamental constants like G or epsilon_0, to use things like the electron charge (or possibly 1/3 of that because quarks), which have a straightforward interpretation as a physical quantity, as the foundation. So, like the Planck units, the base unit of velocity would still be c, but the base unit of charge would be e, rather than, uh, whatever falls out by combining epsilon_0 and mu_0 etc. Because there’s no similar unique object to use for the base mass, I would say to use the mass of a hypothetical object such that the gravitational force between two copies of it at a given long distance would be the same size as the force between two unit charges at the same distance, and, for the base unit of angular momentum, use the intrinsic angular momentum of, any spin 1/2 particle. These together should be enough to define a full system of units, with scales very similar to the Planck scale, but unlike the Planck scale, the foundational values for it are all physically immediately meaningful quantities, rather than like, conversion constants. (Though, again, it really is a fairly small change.)

[@zachariemelanson485]

Why can some form of energy form a black hole, but others can't? For example you can theoretically give a body enough thermal energy that it will turn into a black hole, but as far as I'm concern it's not the same for potential energy or even kinetic energy (tell me if I'm wrong, I really don't know). It's like potential and kinetic energy would need to be "released" somehow in a collision or something. I just can't seem to shake the feeling that they are fundamentally different in some ways.

[@neonblack211]

Didn't Richard Feyman say something about the energy constant like "it's not a "stuff" it's a number that we assign in order to do physics, If it wasn't there we would simply use another (number)

[@JoshBrown42]

It seems like in a lot of places the Law of Conservation of Energy is almost a tautology. When we look at a novel situation and try to figure out the energies involved, we often work backwards from conservation to figure out how to calculate them. In that sense if energy is just defined as a particular "thing that is conserved," does it even make sense to talk about a conservation law?

[@JoshBrown42]

One thing seemingly pulling (ha) for a physical interpretation of energy is gravity. Beyond merely being conserved, the presence of energy warps the spacetime around it. In the same way that asking "why do inertial mass and gravitational mass have the same value?" leads to some interesting science, I wonder if there is anything interesting to be discovered by looking at why the energy we conserve in mechanics is the same energy we use in general relativity to determine how much spacetime curves.

[@jonathanharrop2978]

Thank you.

[@anattasunnata3498]

Thanks for the video! As a self taught person with little background in physics, I've watched a lot of videos trying to explain to laypeople what does the concept of 'energy' mean. However, in almost all of them, after fishing watching them, I'm stuck with a weird feeling: I feel like, if asked about the content of the video, all I can do is repeat what I've heard or to confess that I've learnt nothing. Sadly, this is what happened to me in this video (which is not the case for other videos of yours). Maybe, this feeling or my lack of abilities to understand this concept stems from my lack of math training. I suspect that that has some part on it. But I also think that it has to do with a common problem with the explanations given to this concept: they do not point to a clear referent. After all, the mathematical concept is referring to something else: whether to another concept, a thing, an atribute, an event or a process. At the end of the video, you sum up the content of it by stating that it doesn't matter what 'energy' is, but how it changes. But I cannot understand how energy is changing if I don't grasp the referent of 'energy' in the first place. To be clear, I'm not saying that this is your fault. I think that the problem lies in the concept itself, and how it is understood by physicists. Mario Bunge, a physicist and philosopher, has pointed out in a paper he wrote in 2000, that the concept of 'energy' is not a physical element as, for instance, velocity is. He states that it is, instead, a general concept, just like "entity" or "change"; in short, it is a metaphysical concept, because of its hypergenerality. If you're interested in this idea, the title of the paper is "Energy: Between Physics and Metaphysics", by Mario Bunge. I'd be really awesome if you could give us your opinion on his proposal. Have a wonderful day, and thanks again for your magnificent videos.

[@drdca8263]

Have you looked into Noether’s theorem?

[@Gwunderi25]

Don't think it's because of a "lack of math training", but, you say it: "they do not point to a clear referent." You can only assign a certain amount of energy with respect to something else. If you hold a stone in your hand, it has a potential energy with respect to the ground. Or take an object in space (without gravity): without a reference point you can't say if it is moving at a constant speed or if it stands still. So what's its kinetic energy? It stands still, so its kinetic energy is zero. But if it is about to collide with a metorit, than it "suddenly" has a kinetic energy depending on its speed relative to the meteorit. So you must first define a "clear referent" to speek of energy - that's what is mostly just "assumed" to be known.

[@anattasunnata3498]

@@Gwunderi25 Thanks for your reply. With "referent", I meant the object towards which the concept of 'energy' points out. I'm not referring to the object that "possesses" some amount of energy; I'm trying to clarify what is that 'thing' that it is being "possesed": what is "energy" in general, or what is is common to all those instances when we talk about "X having such amount of Y kind of energy". I don't know if I'm making myself clearer with this explanation. Have a nice day!

[@lorigulfnoldor2162]

@@anattasunnata3498 Do you grasp the "color" of an object as having a referent? Color is not object - you cannot point at some object and say "this is THE red" or "this is THE yellow". Yet there are yellow or red objects. It may be hard to define in words what color IS, but it can be shown easily to someone who has eyes. You can talk about the change of colors, too, as leaves in autumn change their color from green through yellow and orange to red. Come to think of it, light-waves of different colors also actually have different energies - the more "red" it is, the less energetic, the more "blue", the more energetic.

[@Music_Creativity_Science]

Good video as always, but it, as nearly all such videos, misses an important point concerning energy conservation. A moving object, as a whole object, does not have more energy than an object which is still relative to it (which has not been accelerated). The accelerated/moving objects internal energy (speed of subatomic particles + binding energies between them) is reduced with exactly the same amount of energy as its kinetic energy in the macro world. What then happens when the moving object collides with an object standing still, is that internal energy is immediately released when electrons, quarks etc go back to their "normal" rate of change. In a hard collison (immediate stop) they have very little time to do that, therefore a lot of energy released in very little time. This changed rate of change concerning electrons, quarks etc is also basically relative time, and the physical reason why the accelerated twin in the twin paradox (special relativity) returns younger. So acceleration (which needs energy) causes speed, which causes internal changed rate of change on the quantum level to balance the kinetic energy in the macro world, which causes time dilation.

[@vijayalakshmis4473]

Please sir make a clear video about what is mass and weight???

[@Sam-cs6hu]

Why can’t work simply be defined as the dot product of force and distance? That way energy can be defined as the work a system need to do/receive so that the system turns into a reference state(set velocities and positions for all parts). If we only define energy as something conserved then one can easily say momentum and angular momentum are energy.

[@joyrosarian7249]

Bro plz put video on magnetic Anisotropy

[@Wrackey]

I like to think of energy as a abstract term for any kind of imbalance, like money is a abstraction of value. You can bring one part that is out of equilibrium, into (or more into) equilibrium, by pushing another thing out of equilibrium. In that sense, I regard kinetic energy and potential energy as the same "level", and more conceptual: As in: Able to move towards a new equilibrium (and in doing so, expending energy) when the conditions change, but not sooner: A moving object doesn't change any so to say "scales" until it interacts with something else, much like a heavy object in gravity doesn't change any scales until it starts to fall. What we eventually end up with as any kind interaction releases heat, is just tiny electromagnetic waves, that oscillate around their 0 value.. the heat death of the universe.. when "energy" is all spread out, into small and useless imbalances in the electromagnetic field.. like the ripples in a pond ;) The big bang being a big imbalance that started to ripple out, and the universe and everything we perceive just being what that ripple looks like as it spreads out ;) ... I like that image. I don't know if this makes ANY sense ;)

[@vimadmax]

it all makes sense, if you take general relativity into account and 4 dim space time. Mass is basically energy, so kinetic energy is how mass interacts with fabric of space time. Potential energy of a gravity well is kind of the same, it connects the curviature of space time caused by another mass with kinetic energy of the moving body.

[@niloymondal]

Please make an explanation of General Theory of Relativity in a 1 space, 1 time universe.

[@colinmunro2632]

Just some thoughts about energy. Is it meaningful to talk about the total energy of the universe especially as kinetic energy will depend on your reference frame? Also if celestial bodies are moving apart because space is expanding like spots on an expanding balloon, do these 'spots' have kinetic energy? Also the idea of parallel universes created at the collapse of the wave function will break the conservation of energy principle as would time travel.

[@drdca8263]

The expected value of energy is conserved, (though measuring it may change it to a particular value that differs from the expected value. Though, if you take MWI interpretation, I guess the average of the measured values, weighted by the weight of the “worlds”, would be the same as before)

[@jithunniks]

Can energy be negative?

[@aaronnorman9755]

I think so, but because it’s a scalar quantity the negative would mean a deficit in energy, rather than the opposite direction.

[@DrDeuteron]

binding energy is negative

[@vitaminprotien1644]

Of course 🙃

[@javedpervez3237]

Abe sale

[@srishailspujar6278]

Hey man.......if u can do a video on thermodynamics and explain all the different kinds of processes with the conditions ill be so grateful to u.......please.........

[@srishailspujar6278]

like man the energy transfer and pressure volume energy ....... just sick me brain everytime.....I'm not able to understand.....

[@shashankchandra1068]

In beta minus decay process is mass of neutron (before it's decay) greater than mass of proton and w- boson ??(bcoz some of it's mass is convereted into energy right??)

[@DrDeuteron]

don't forget the W+ boson.

[@schmetterling4477]

We are spending more or less a whole year on explaining the energy concept in high school science class, aren't we? From all I can tell it simply doesn't sink in. People can not remember the simple "energy is the ability of a system to perform work on another system" definition.

[@BryanBarcelo]

Energy is motion in all of it's forms. Speed, brightness, weight, time, color, intensity and temperature are living things perceptions of Energy in it's various forms.

[@WestOfEarth]

It seems like there's a distinct difference between kinetic and potential energy, and rest mass energy.

[@othersveryrare3667]

I want to know what is actually electron weave? I mean we see a wiard picture of weave in books, but that is only graphical conversation. What is actually weave physically? I mean how does it looks like in physical world?

[@valentinmalinov8424]

Probably you can find the answer to your questions in my book - "Theory of Everything in Physics and The Universe"

[@marinosalilin6984]

Hi! Very nice video. have you already covered what is time?

[@jlpsinde]

Hi very good

[@jayant4444]

Please make a lecture on TENET movie based Physics

[@primemagi]

what you described is not actual energy. it is like we talk about gravity. we actually talking about effect of gravity. not what it is. all the formula are for computing. energy is created by atom activity. Ferydoon Shirazi. MG1

[@TheTariqibnziyad]

You're just the best, thank you

[@sonarbangla8711]

Rate of change of energy is work and rate of change of work is power, so what is energy?

[@someperson9052]

What's the outro music?

[@dhanashrikulkarni5878]

Few words.... "This is cool!"

[@magicalworld5446]

What are the differences between energy and force??

[@valentinmalinov8424]

Energy is your sandwich, Police is a Force!

[@Higgsinophysics]

You rock parth G

[@innocentarain7900]

hello friend please make video on reduce collapse by Roger Penrose

[@duggydo]

I’ve often wondered what happens to the energy that goes away from redshift as radiation travels across the Universe. Is it absorbed by Spacetime itself?

[@philippenaturel7337]

In General Relativity, there is no conservation law of energy. Energy may vary depending to the spacetime evolution.

[@thecoloroctet1365]

@@philippenaturel7337 just a little nickpick: in in GR the local Conservation of Energy still exists, but it’s on a wider scale that it’s not necessarily the case

[@duggydo]

@@philippenaturel7337 but the energy is lost in every reference frame. It actually can completely fade to nothing if travels far enough across expanding space. At least that’s how I understand it.

[@philippenaturel7337]

@@duggydo yes, the energy of a photon may fade to almost nothing. Oddly, this energy is not transferred anywhere.

[@Petercookintaiwan]

What about the unpredictability of a simple chaotic pendulum? How do energy and the laws of chaos fit?

[@alwaysdisputin9930]

I clean my front door & every day the dust blows in from the car park which no one sweeps (the bastards) & after a few days my door is dusty once more. Once it's cleaned my door has a lot of order. It's tidy. Entropy, (S) is a measure of disorder therefore my door has low S. It took work to reach this state of high order & low S. 1 day later there isn't much dust on the door so it only takes a little bit of energy to maintain the low S. But the sands of time are relentless. The car park is a vast chaotic system of particles & there are a trillion, trillion ways for the door to become dusty each with a slightly different arrangement of dust particles. Since there are so many ways the door can become dusty & only a few ways the door can be tidy it's overwhelmingly likely that over the time the door becomes more dusty & my preferred state of tidy order gradually disappears. All the energy I spent wiping the door was basically like building a sandcastle only to see the tide destroy it the next day.

[@drjohnd.9508]

A mathematical concept is transferred to the surrounding of the car - that's interesting.

[@snehasismaiti342]

Can you make a video on how to get into Cambridge from India?