How does the curvature of spacetime create gravity?

In 1919, Arthur Eddington led an expedition to observe a total solar eclipse, confirming that light passing near the Sun is deflected due to its gravity. This observation supported Einstein's theory of general relativity, which differs from Newton's laws by predicting that massive objects warp spacetime, affecting the path of light.
Einstein resolved a paradox wherein photons traveling different distances (AB vs. CD) near a massive object like the Sun reach their destination simultaneously. According to special relativity, light's speed is constant, so photons traveling a shorter path (CD) should take less time. However, in general relativity, the presence of a massive object causes time to slow down, an effect called gravitational time dilation.
To visualize this, imagine spacetime as a cylinder that, when influenced by a massive object, flares into a cone. Clocks lower in the gravitational field (closer to the cone's wide base) tick slower than those higher up, explaining why time passes differently at different altitudes. This effect has been experimentally confirmed, such as with atomic clocks on airplanes running faster than those on the ground.
Gravitational time dilation can be visualized by imagining two ants, one higher (A) and one lower (B) on the cone. Both move through spacetime at the same speed, but B's clock ticks slower due to the cone's shape. Thus, B ages slower than A.
This curvature of spacetime not only affects the flow of time but also creates gravity. Objects naturally follow the curved paths in spacetime, leading them to fall towards massive bodies. A stationary object's path in curved spacetime slopes toward the massive body, causing it to fall, illustrating that gravity is the manifestation of curved spacetime geometry. This explains why an object falls faster as it moves closer to a massive body and why, hypothetically, an object falling infinitely would reach the speed of light due to the extreme curvature of spacetime.

[@anywallsocket]

The expanding cone coordinates are more intuitive than other curved spacetime videos by far 🙏

[@atticuswalker]

that's not saying much. and changes the meaning of intuitive. to sort of understand. the concensus can't be explained intuitively.

[@walidkhier5640]

I don't claim i fully grasped all the details, but this is the best description i heard of curved space time and how it genrrates gravity. Much, much better than the massive ball placed on thin fabric animation.

[@reidflemingworldstoughestm1394]

That ball on stretchy fabric analogy, along with the order analogy for entropy, need to go the way of the dodo.

[@guilleminbruno7898]

Agree with you. The massive ball placed on a fabric is a nonsense!

[@tennisCharlzz]

It is funny that to demonstrate gravity using stretched material, you need gravity.

[@legendrams548]

Idiots only explain gravity with a stretched fabric and a ball. There is no fabric in space. The perception of top and bottom is only for us. There is no top or bottom for space. There is no direction for space, so there is no possibility of a fabric in one space plane. Also, this idiot should explain where the curvature first come to be in the first place. It is a circular stupid explanation, curvature comes from gravity and gravity came from curvature. Fact is, all physicists are lying to us about the Space.

[@-danR]

It doesn't describe how it generates gravity. In fact, Gravity remains one of the most perplexing phenomena in physics. It explains how space-time, under the _influence_ of a gravitational field causes the attributes of falling objects. It is also defective, as are most such popular expositions, in explaining why _not-falling_ objects-such as the apocryphal apple hanging over Newton's head-seem to be under some mysterious influence. Eg., the mysterious apple(s) seem always to bend their branches _down._ That question always elicits a separate video, such as the ingenious/notorious dialekt's river-model of the matter. Yet others present the baffling accelerating-surface claim about GR: the apple is exerting no force on the branch, the branch is continually accelerating... _upwards_ . Entailed by that interpretation is the understanding that apple trees in southern New Zealand have their branches' acceleration in another direction. If all that is too hard for the average person to grasp, even with the help of some dodgy videos to help you over their spongy arguments, they may eventually resort to the claim that in HS physics the teachers lied to us about the meaning of... _direction._ I think that's easier than redefining the meanings of vectors, momenta, and acceleration.

[@kwisclubta7175]

Sometimes (rarely) I'm in a mindset to understand videos like this. This one hit me in the right way at the right time. Very well done. I learned a lot. Thanks.

[@atticuswalker]

if you believe it. and ignore the contradictions.

[@Poopoopeepee6969]

@@atticuswalkercontradictions?

[@drakeeblis1788]

@@kwisclubta7175 so, in other words you are mesmerized by the bullshit...

[@artofplanets]

I'd be curious to know how to calculate how long it would take for two masses to get to the speed of light by mutual gravity and how far apart they would have to start. I'd like to know if that's really possible with anything that doesn't include a black hole as one of the objects.

[@bbbf09]

Its never possible to reach the speed of light ...ever. ...unless it involves event horizon of black hole. Here spacetime is falling into (or rather warped) at light speed but only at point of event horizon. And once at that that horizon you are never coming back to report. A neutron star is closest next thing and you could crash into one of these at 99%+ light speed.. but never at 100%. You can have 2 neutron stars at 2 solar masses each crash together. They would crash together at 100% light speed but the boundary of where that happened would be exact the formation of a new event horizon of a new black hole which (as we know from theory and now from gravity wave evidence) always forms from merging of neutron stars.

[@aimwell7089]

Damn, you guys are good. I am kinda keeping up (when somebody offers amazingly structured explanation mostly) and i always feel like i would need a little bit more IQ or computing/projecting brainpower to join the top thinkers. Maybe a lot of power lol looking at some of the complex math implications some ppl can do. Hopefuly big part is knowledge and training and im not actually too far apart to justify using the word "im actually stupid conpared" 😅

[@O-Kyklop]

Eddington’s „observation“ was technically a joke. He had not even the needed instruments, or the needed accuracy to perform such observation. He just wanted „to confirm“ Einsteins prediction…no matter what.

[@greggstrasser5791]

It's incredible how the press just picked up on Einstein after that.

[@O-Kyklop]

@@greggstrasser5791 At first sight, yes.

[@markgraham2312]

This explanation of gravity as an effect of curved-space-time is mind blowing.

[@hosoiarchives4858]

It’s old. However it’s rarely explained properly

[@JoeDeglman]

The use of gravity to illustrate "space-time" which in turn causes gravity is not an explanation. Also, Einstein's failed General Theory implies that gravity is not a force also implies that light and massive objects should follow the same path through space and that light is not affected by gravity, because of the claim that light is massless, yet His General Theory implies that gravity can suck light into a hypothetical singularity. The entire General Theory of Einstein is built on impossible conundrums. Light bending in an atmosphere was always considered to be why light bends in the Sun's atmosphere. Others had predicted this refractive index accurately prior to Einstein, such as Soldner. Einstein simply did not understand this concept of refractive index in optical lensing. Gravity is caused by the implied flux density gradient of Gauss's Law for Gravity, which acts as an energy gradient, confirmed by GPS and atomic clocks.

[@markgraham2312]

@@JoeDeglman Where is the evidence that General Relativity has failed? Where? Proof by assumption statement like this is typical of someone with a pet belief and no education. General Relativity states gravity is a force. Someone has not read the General Theory of Relativity. Light being affected by gravity is what General Relativity is all about. Where did you get this stuff? Are you familiar with the experiments? "His General Theory implies that gravity can suck light into a hypothetical singularity." - No. Have you ever taken a course in physics?

[@geoffwales8646]

@@JoeDeglman Light bends around large masses as can be seen in galactic halos.

[@JoeDeglman]

@@geoffwales8646 the JWST also shows that these galactic halos also have a substantial dust atmosphere that acts as an optical lense to do the bending as a refractive index. Just like the Sun, bending of light only occurs through an atmosphere as a refractive index as an optical lensing function. No bending of light has ever been observed through the vacuum of space around a massive object, in contradiction of the GRT, where there is no atmosphere. The previous images of galaxies from Hubble were in the optical range and the dust atmosphere wasn't observed previously because the atmosphere of galactic halos emits in the infrared not in the visible. .

[@HowDoYouKnowThough]

2 questions that the video made me confused about. 1. The initial flashlight beam of light had to have been significant in width for the difference in distances traveled between top and bottom "light fibers" to be different. Was the initial experiment based on two stars spaced far apart from one another? In that case, how did we determine that the light arrived to us from each star at the same time, since light has always been streaming from them to us, and we don't know precisely when a given photon was emitted? 2. When you roll up the spacetime diagram and say that "light only travels through space," I understand this is correct from the photon's perspective, but you appear to be rolling up the stationary apple's spacetime diagram. Wouldn't that diagram also have light spiraling along a helix, since from the apple's perspective light travels through the apple's time at a 45 degree angle to apple's space? It seems like you are mixing/combining the apple's perspective into the photon's perspective into one unified spacetime manifold, on which I just don't understand how you can be certain about the geometry of circular, helical, and straight line paths coursed out by different material objects. Maybe we can call this some higher dimensional "God's" spacetime manifold who sees the absolute truth in terms of distance and time?

[@REDPUMPERNICKEL]

Two very excellent questions.

[@mrmoose1599]

@@HowDoYouKnowThough so we don’t spiral along. We move in a straight path along curved spacetime. This was found out by how light acted. We took measurements of this and found out the limit to motion of mass & energy as the equivalence principle was found. Taking this into account we know have lights constant speed over distance and distance. Hell that means to get time (the rest of the equation) we just plug and play. Let me know if ya have any questions

[@glenwaldrop8166]

​@@mrmoose1599there's no such thing as a straight path of you want to really get into it. Space is not straight, there are no fixed points anywhere in all of existence and everything is moving at a relative speed and rate of time to everything else.

[@mrmoose1599]

@@glenwaldrop8166 bro just read that again. I didn’t say otherwise

[@glenwaldrop8166]

@@mrmoose1599 the point you were making was a bit pedantic, I went a bit further. Everything is relative, everything interacts with everything, there's literally no such thing as a straight line.

[@ritikasriv13]

By far the best explanation I’ve seen! Thank you

[@citizen_cicero]

The correct question is: why does mass curve spacetime?

[@geoffwales8646]

The correct question is, why and how does the Higgs field give objects mass?

[@DrZedDrZedDrZed]

If someone knew that, they’d already have multiple Nobel prizes.

[@chrisstevens-xq2vb]

Spacetime is just math. It does nothing.

[@SeanGilchrist]

Because mass is a degree of freedom that deflects momentum.

[@VonJay]

@@geoffwales8646Higgs field contributes 1-2 % of mass to protons and neutrons. The rest of the mass comes from the binding energy of the strong force

[@janhorak8024]

The cone visualization was the core point making this video great. Thanks a lot, perfect explanation.

[@sergejstojanovic2518]

Stop using miles....

[@1darkseiders]

Yep, science is international, maybe use the SI?

[@ExistenceUniversity]

If you're so informed, why are you here?

[@skilz8098]

I'm not against the use of SI, but I am against the notion of one person or a group of people telling others what convention they can or cannot use. I use both conventions, and I also use proper conversions when necessary. It all depends on the context of the problem that I'm working with. I do not buy fuel by the liter. I buy it by the gallon, and I measure my vehicles economic efficiency based on miles per gallon. When I buy milk, I buy it by the gallon or 1/2 gallon, not by the liter. Again, it all depends on the domain and context of the workspace. Now, if I was working in a lab and doing some chemistry and or physics, perhaps I would use the SI units, but again that still depends on the domain, context and workspace of the current problem. Only someone who is either ignorant or arrogant wouldn't understand this. I have the understanding and intelligence to use multiple formats and conventions, and I'm sure there are many others that do too. There is nothing wrong with someone else using miles as opposed to kilometers. Also, when I step on a scale to measure my weight, I'm measuring weight in lbs., I'm not measuring my mass in kilograms. The comment alone "stop using miles..." is condescending.

[@Totaro77]

No

[@Kinze02]

​@skilz8098 Yeah whatever, the entire world uses kilometers.

[@onurthemonur]

The cone analogy, this is the best illustration I've ever seen!

[@huetang]

really..."the iron ball would reach the speed of light". as far as physics goes, objects with mass can't ever get to the speed of light.

[@ragnaarminnesota6703]

Inside a blackhole? Speed of communication.

[@DABmonger]

If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.

[@diezzleking2890]

You’re confusing the speed of time with the device that’s measuring time . Time is not speeding up or slowing down , it’s the device that you’re using to measure time that is measuring it faster or slower . Time is a constant and doesn’t speed up or slow down , however the device measuring it does .

[@neilbailey1139]

Yes. Time is a constant. The device measuring time changes

[@waynegarrett9183]

Yes … the device you are using to measure “time” is affected by its place in a gravitational field, and the various accelerations it undergoes… once you account for those variables, any differences in two time measuring devices will be factored out …

[@kpbalaji]

Does it apply for digital clocks too?

[@diezzleking2890]

@@kpbalaji Yes

[@colt5189]

I don't get how the iron ball would reach the speed of light? That's not possible as it has mass.

[@salvatronprime9882]

It would have to travel an infinite distance

[@canadians4trump2024]

this one bugged me too, I figure it's more of a philosophical comment sprinkled in to add additional context.

[@PerryEmpire]

That's why iron will be burnt down at some point due to heat and pressure in my point of view. The faster it goes the more mass it gains.

[@DABmonger]

​@@canadians4trump2024Or lack of knowledge and understanding.

[@DABmonger]

If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.

[@nicolaspeters2555]

How can the clock on the plane tik slower? Another video about relativity shows the faster one travels, the slower time passes.

[@mrmoose1599]

It’s distance over velocity is different therefore it’s clock will count differently

[@EvicFiniteGen13]

man been trying to wrap my head around this, but after watching this, i get it a little...

[@francus7227]

Me, too. Emphasis on LITTLE.

[@trenken]

The thing that throws people off is this name, “curved spacetime.” Sure, when you look at a rolled up piece of paper, or a digital graphic, we see the curve. But in reality there is no curve. Space is devoid of geometry. There is nothing surrounding the earth. Its literally enpty space. Wheres the curve? You have to remember that einsteins theory is just that, a theory. Yes it happens to align with how we perceive things to work, but it doesnt provide all the answers. Its just the best explanation we currently have. We dont understand the nature of space. Thats the issue here. When you consider this example, a rolled up piece of paper, that is one way to describe gravity. But the age old question remains unanswered, WHY does gravity exist? I believe thats something we can never know. Einstein explained the how. The why he had absolutely no idea. No one does, and no one ever will. Thats why after watching all these gravity videos, everyone has the same response, “eh, i guess it makes sense.” It can never make total sense until we understand the fundamental nature of the universe. Unknowable unfortunately. Why are things attracted to each other? Who knows, the just are 😁

[@francus7227]

@@trenken I read your post... Earth is surrounded by space. Einstein said there is no space or time... it's space time. You changed it to JUST space.

[@jupanulkyrre1234]

​@@francus7227it's just space because you don't know nothing about time...

[@Poopoopeepee6969]

@@trenkenmaybe that’s the life cycle of matter? Create black holes basically.

[@lowersaxon]

If the Eiffel-Tower were of infinite hight there would be no gravity at all. This is a classical solution which is duplicated by GR in the Newtonian limit of „weak gravity (earth) and slow speeds (v

[@fjbayt]

Can you expand just a little more and in the extreme case of going trough an event horizon where the time and space axis switch? How would you represent that in a video graphic? And by the way....excelent video!

[@KaiVieira-jj7di]

For a particular choice of coordinates, the Schwarzschild-Droste coordinates, the temporal and radial components of the metric tensor switch algebraic sign.

[@romanjanek5283]

Understanding the "switch" is easier than many think. It sounds brain-bending that time and space switch places, but it's really just the fact that the singularity is the ONLY future of your light cone. Because anywhere you would like to maneuver when "falling" into a black hole, you will ALWAYS (100% of cases) meet the singularity (it's just in your light cone across all possibilities). The Penrose diagram has this brain twist in it, but from a simpler point of view, it's just that. Like when it's Friday night and you are out with friends, the beer is your 100% future :D (if you drink). I like to hypothesize that all singularities are the same (like in the SAME spot), because when you have a spherical universe (like an expanding balloon and space-time is its surface), when you do this 90-degree warp (like black holes do) from the surface, eventually this warp ends in the middle of the sphere. So all black holes point to the same "space/spot/something/singularity" :) . Just food for thought.

[@mrmoose1599]

@@fjbayt much like going over a waterfall

[@peterdamen2161]

The time and space axes never switch. That is nonsense. Time is time and space is space. Minkowski was wrong with his quote ("Henceforth, space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality")!

[@peterdamen2161]

@@romanjanek5283 FYI: singularities don't exist and time and space don't switch.

[@nunya3399]

If you’re directly between two massive objects of the same mass, does time pass as if you were on the surface of either one?

[@mrmoose1599]

No. Outside objects and surface of object will yield 2 different times

[@nunya3399]

@@mrmoose1599 but it would average the two? As you move away from one time is speeding up but as you move closer to the other it’s slowing down, so there has to be a point in the middle that matches the surface time right?

[@mrmoose1599]

@@nunya3399 ah I see what you are getting at. We do account for travel gravitationally and by acceleration. Gravity is general relativity and acceleration is special relativity. When gps orbit earth it accounts for both. So not were they meet in the middle just where we account for both

[@pretzelogic2689]

You got it wrong. The curvature of space time is a symptom of gravity.

[@jayceasar2661]

hey you mite be on to something

[@bbbf09]

Nope... you got it wong. Acceleration along space axis . . what we call gravity. . . is direct result of warping of space-time... more specifically differential time. Not the other way round.

[@pretzelogic2689]

@@bbbf09 Why does space warp?

[@bbbf09]

@@pretzelogic2689 Space-time (4 dimensions) is what warps - not just space. It is a fundamental fabric of the universe. It does so in the presence of any energy-momentum. Since mass (matter) has an equivalent energy (E=mc2) then it also warps in the presence of mass (any mass size but more noticeable for us with planet size masses like Earth) . That warp gives rise to differences - a gradient - in the flow of time which gives rise to space (which rememeber is connected to time as 4D fabric) flowing in towards the direction of the warp (towards the mass) - which we experience as an acceleration and historically have labelled it as a force of gravity. So it is warped space-time gives rise to what we call gravity. Not the other way round. To go into greater depth involves EInsteinian tensor mathematics. A bit too much for youtube comments section.

[@bbbf09]

@@jayceasar2661 Prove what exactly? that time flows at different rates depending on how close to the energy-momentum (mass) centre you are? Without accepting that the algorthim in your GPS makes allowance for this - then it would not work and you couldn't use google maps to go anywhere. 'Proof' enough for you?

[@82bluedream]

Question? since even deep space contains micro-gravity, what is creating the micro-gravity? The Gravity Probe B experiment detected something called "Frame Grabbing", where the Earth is grabbing space/time as it turns on its axis. Wonder if this had been further examined as to impacts to time?

[@rafaelhubbard66]

Best explanation yet

[@alexandervouzenthal8163]

6:00 why though? Why is the object moving towards a space where time passes slower?

[@morten3219]

i thought the same. If the object is standing still and only moves through time it should just follow the time path. So why it starts shifting towards the space part of the diagram i can understand either and the video doesn't explain this

[@jonathanspruance4502]

Because of the warping of spacetime. The object was moving in a straight line through spacetime, along the time axis. Now the presence of the massive object has caused the underlying 'grid' of spacetime to warp in such as way that the line of movement through spacetime (ie geodesic) is no longer parallel with the time axis but pointing into the space axis as well. So some of the movement through time is diverted into movement through space in the direction of the massive object. No external forces are acting on the object - the shift of movement into space is caused by the change in spacetime geometry itself. Pretty mind bending.

[@itheuserfirst3186]

The shortest distance between two points is a straight line. All celestial bodies warp the "fabric" of space, and create gravity wells. When a smaller object comes close to the rim of a larger object's gravity well, it gets caught in that object's orbit through mass bending space-time. It's similar to how water circles a drain, but it's an all directions. Everything in space is falling.

[@REDPUMPERNICKEL]

@@jonathanspruance4502 I am sitting here glued by gravity to my seat (and by my interest in the topic). But since I am absolutely certain that 'time' is a concept only, I'm in need of a different explanation. What is it in actuality that the temporal concept is actually 'about'?

[@grahamthomas7821]

"Light beams which only move through space..." I cannot get my head around this. So light doesn't move through time?

[@mrmoose1599]

@@grahamthomas7821 technically they do but it’s the shortest time. All massless objects not just light

[@reidflemingworldstoughestm1394]

Not only do objects moving at light speed experience time as zero, the space between their origin and where they land is compressed down to zero distance as well.

[@mrmoose1599]

@@reidflemingworldstoughestm1394 that’s perspective.

[@reidflemingworldstoughestm1394]

@@mrmoose1599 That's physics. Perspective is drawing.

[@mrmoose1599]

@@reidflemingworldstoughestm1394 perspective can be drawn but isn’t strictly drawing.

[@youngandrew66]

That's the backing paper from book covering film... wow, it's all so simple.. but where did the book covering go?where did it come from and if we join the two sides together will it create a worm hole between Rymans and Smith's?

[@williamwalker39]

The speed of light is not a constant as once thought, and this has now been proved by Electrodynamic theory and by Experiments done by many independent researchers. The results clearly show that light propagates instantaneously when it is created by a source, and reduces to approximately the speed of light in the farfield, about one wavelength from the source, and never becomes equal to exactly c. This corresponds the phase speed, group speed, and information speed. Any theory assuming the speed of light is a constant, such as Special Relativity and General Relativity are wrong, and it has implications to Quantum theories as well. So this fact about the speed of light affects all of Modern Physics. Often it is stated that Relativity has been verified by so many experiments, how can it be wrong. Well no experiment can prove a theory, and can only provide evidence that a theory is correct. But one experiment can absolutely disprove a theory, and the new speed of light experiments proving the speed of light is not a constant is such a proof. So what does it mean? Well a derivation of Relativity using instantaneous nearfield light yields Galilean Relativity. This can easily seen by inserting c=infinity into the Lorentz Transform, yielding the GalileanTransform, where time is the same in all inertial frames. So a moving object observed with instantaneous nearfield light will yield no Relativistic effects, whereas by changing the frequency of the light such that farfield light is used will observe Relativistic effects. But since time and space are real and independent of the frequency of light used to measure its effects, then one must conclude the effects of Relativity are just an optical illusion. Since General Relativity is based on Special Relativity, then it has the same problem. A better theory of Gravity is Gravitoelectromagnetism which assumes gravity can be mathematically described by 4 Maxwell equations, similar to to those of electromagnetic theory. It is well known that General Relativity reduces to Gravitoelectromagnetism for weak fields, which is all that we observe. Using this theory, analysis of an oscillating mass yields a wave equation set equal to a source term. Analysis of this equation shows that the phase speed, group speed, and information speed are instantaneous in the nearfield and reduce to the speed of light in the farfield. This theory then accounts for all the observed gravitational effects including instantaneous nearfield and the speed of light farfield. The main difference is that this theory is a field theory, and not a geometrical theory like General Relativity. Because it is a field theory, Gravity can be then be quantized as the Graviton. Lastly it should be mentioned that this research shows that the Pilot Wave interpretation of Quantum Mechanics can no longer be criticized for requiring instantaneous interaction of the pilot wave, thereby violating Relativity. It should also be noted that nearfield electromagnetic fields can be explained by quantum mechanics using the Pilot Wave interpretation of quantum mechanics and the Heisenberg uncertainty principle (HUP), where Δx and Δp are interpreted as averages, and not the uncertainty in the values as in other interpretations of quantum mechanics. So in HUP: Δx Δp = h, where Δp=mΔv, and m is an effective mass due to momentum, thus HUP becomes: Δx Δv = h/m. In the nearfield where the field is created, Δx=0, therefore Δv=infinity. In the farfield, HUP: Δx Δp = h, where p = h/λ. HUP then becomes: Δx h/λ = h, or Δx=λ. Also in the farfield HUP becomes: λmΔv=h, thus Δv=h/(mλ). Since p=h/λ, then Δv=p/m. Also since p=mc, then Δv=c. So in summary, in the nearfield Δv=infinity, and in the farfield Δv=c, where Δv is the average velocity of the photon according to Pilot Wave theory. Consequently the Pilot wave interpretation should become the preferred interpretation of Quantum Mechanics. It should also be noted that this argument can be applied to all fields, including the graviton. Hence all fields should exhibit instantaneous nearfield and speed c farfield behavior, and this can explain the non-local effects observed in quantum entangled particles. *KZbin presentation of above arguments: kzbin.info/www/bejne/qZazlX1tq7iErLM *More extensive paper for the above arguments: William D. Walker and Dag Stranneby, A New Interpretation of Relativity, 2023: vixra.org/abs/2309.0145 *Electromagnetic pulse experiment paper: www.techrxiv.org/doi/full/10.36227/techrxiv.170862178.82175798/v1 Dr. William Walker - PhD in physics from ETH Zurich, 1997

[@walidkhier5640]

Interesting, but it is a book rather than a comment.

[@williamwalker39]

​@@walidkhier5640See my short KZbin presentation.

[@mrmoose1599]

Well it’s been proven and you can say otherwise but your comment and sources don’t disprove relativity. It all works very well.

[@williamwalker39]

If the speed of light is not a constant then Relativity can not be correct, any theory based on it is also wrong. General Relativity is not compatible with Quantum mechanics. So either one or both of the theories is wrong. The evidence I present says Relativity is the problem. Science will not advance , if the foundations of physics is not challenged.

[@williamwalker39]

​@@mrmoose1599If the speed of light is not a constant then Relativity can not be correct, any theory based on it is also wrong. General Relativity is not compatible with Quantum mechanics. So either one or both of the theories is wrong. The evidence I present says Relativity is the problem. Science will not advance , if the foundations of physics is not challenged.

[@antonellodigioia]

In 7:24 minute you show curved space and the apple that falls. Please can you show all unit measures of curved space time when the apple falls with 9,81m/s^2 acceleration?

[@faridehamjadi5289]

beautiful explanation and illustration.

[@kasulu57]

Watching different videos is making my understanding better and better. An excellent presentation in a different way on time dilation.thanks a lot

[@DABmonger]

Take a look at the comments, and you'll see that there's major errors in this video.

[@kakhaval]

The assumption that all photons from A/B should reach C/D at same time needs a proof. It may not.

[@atticuswalker]

they don't. we saw the same light from a supernova . arrive 3 different times.

[@stoppernz229]

@@atticuswalker Not equivalent , with the earth scenario its a single mass and photons are taking a similar path , with a supernova the light take wildly different paths

[@ragnaarminnesota6703]

@@stoppernz229 Because spacetime curved. Floathead says the same thing as this guy.

[@wiktorchm]

@@atticuswalker did you?

[@atticuswalker]

@@wiktorchm what. see the light myself. nope. but I haven't seen the cmb either. don't doubt it's real.

[@cgab12]

If you take the derivative of the space time curve at any point along the curve, will you obtain the acceleration due to gravity at that point as determined by the inverse square law?

[@TerranIV]

The gravitational field is not necessarily stronger at the bottom of the ocean trench, as it is highest at the Earth's surface and then gets weaker as one approaches the center of the Earth (where there is no gravitational field at all). So while clocks do go faster higher in the atmosphere, they will also go faster at the center of the Earth.

[@astronomy-channel]

Excellent point

[@KaiVieira-jj7di]

A clock at the surface of the Earth runs faster than a clock at the center. Not by much, the time dilation is 1.0000000003 between the core and surface.

[@KaiVieira-jj7di]

@@fjbayt NO - the time dilation runs proportional to the Newtonian potential, which is lowest at the center of the Earth.

[@fjbayt]

@@KaiVieira-jj7di You are right, my mistake, i got confused, i ll erase the comment

[@DABmonger]

Interesting. I've just been taking a look at 'How Does Gravity Work Underground? (An In-Depth Explanation)'

[@kelvinharris4921]

I hypothesize: That the universe was not created by the Big Bang. The Big Bang was the manifestation of the true cause of the event. The true cause of the event that created our universe was " Interdimensional balancing " Not to be confused with the multiverse. But with our universe and its subatomic universe as well as its interdimensional universe. When one of these universes becomes void or close to void of matter the other universes are holding the matter that used to exist in it. When the tipping point is reached, they dump all of their matter into this space that will be home to a new universe and then the sharing begins where each universe starts passing material back and forth to one another through half-life radiation or black hole digestion. The effect we call the Big Bang Was the manifestation of this rebalancing. And if this is true it will occur again and has probably occurred billions of times before in the past. So, it's not the Big Bang that created the universe it's interdimensional balancing!

[@ExistenceUniversity]

Great video

[@ltandrepants]

if light propagates in all directions then why and how do we see/locate the object emitting light? wouldn’t we see the light from the object everywhere?

[@jeffroberts6865]

I think you are mixing up gravitational time dilation (GTD) with spacetime curvature. GTD arises when you think you are stationary and yet you are actually in an accelerated frame of reference, as indeed we are standing on the surface of the Earth. GTD is observer dependent, meaning it is possible to find observers that do not see it (a free falling observer won’t experience GTD for example). Where there is GTD, there is apparent (or fake) gravity. Once we accept the Earth is accelerating upwards, it is actually unsurprising that objects appear to fall and that all objects regardless of their mass ‘fall’ at the same rate, because the Earth is actually accelerating upwards at the same rate. Most of what we see as gravity on Earth is because of its acceleration upwards. What is holding the Earth in, keeping it the same size? Spacetime curvature. Spacetime curvature is caused by mass and energy. It is observer independent; all observers will agree on the curvature. Spacetime curvature is what gives rise to real gravity, and what attracts objects together in space. It emerges in the form of what we call tidal forces. The rolled up diagram you used is flat spacetime but rolled into a cone to illustrate the time dilation. That time dilation is GTD. GTD arises from an accelerating reference frame. When it is flattened out the time axis is curved, while the free falling world line (of a falling object) is not. This is a specific version of a spacetime diagram describing flat spacetime (not curved) and actually drawn from the perspective of a free falling body. The time dilation on the curved diagram is a result of a mapping between the object’s inertial frame of reference and our (standing on Earth) accelerating reference frame and is not the same thing as spacetime curvature. The free falling body has no acceleration itself and sees us and all the Earth accelerating towards it.

[@RapsRacks]

One of the best explanations I have seen. Thanks

[@empatikokumalar8202]

How skillful are scientists in explaining problems they cannot understand with fabricated solutions? They create a paradox with nonsense questions, and then they think they have solved that paradox with another nonsense. The speed of light is constant only if they are in the same plane. When the plane is different, the speed is different. For example, the near beam should reach the large mass earlier because it travels less distance than the far beam logic. It's not like that, though. The ray that stays away from the larger mass appears to arrive at the same time because it moves faster than the one that is closer. When you incorrectly construct the universe, light and movement, such absurd questions and solutions are called science. This is not science. He's deceiving people

[@juanvelez7186]

Your comment may be deceitful even to yourself, there is a big difference between hypothesis and fact.

[@Lleanlleawrg]

Seems wild to claim scientists are just full of nonsense and 'construct the universe' incorrectly, hinting you have all the answers.

[@drakeeblis1788]

Another thing that seems quirky and weird to me is how can light speed up and slow down, or slow down and speed back up depending on the medium that it's going through... And they call this a 'constant"⁉️😂

[@Lleanlleawrg]

@@drakeeblis1788 No. It's specifically the speed of light in a vacuum. And it's not primarily about light. Light is a massless particle hence travels at C in a vacuum. But can be slowed by shining through non-vacuum.

[@empatikokumalar8202]

@@drakeeblis1788 Let me explain please. First of all, it is necessary to know what light is and how its movement occurs. As you know, the space that is thought to be empty is actually full. It only has a much sparser texture compared to mass. I think that at this point, weak force or weaker forces are involved. (weaker force has not yet been fully defined) weaker force is the subatomic particles that I call formation points, which are too weak to be mass. They move just like a Newton pendulum. But they are connected to each other in every direction. The reason for quantum fluctuations is their movement. The most important task of these structures is the communication network with the ebb. In other words, light seems to move through these structures. Just like the balls from a Newton pendulum do not go anywhere but transmit the movement. Think of it in the same way but in 3 dimensions. The distance between the balls increases or decreases the speed of light. If the distance is greater, therefore it means it is farther from the mass, then light moves faster. Because there is no time between two formation points. It is the collisions of two or more formation points that express time. I hope this was a sufficient explanation for you to understand. In fact, the topic is so broad that it is harder to write. Thank you for bearing with me.

[@dpatulea]

So that means in a wormhole where the space could be infinite the time slows down almost to a stop and the speed grows as much as it almost gets to the speed of light ?

[@rrrobinson97202]

Does light really bend? When looking at a fish in water, why is the fish ahead when looking through water? Could the same happen in space near a planet or star?

[@sergioapfelbaum5160]

Excelent quality of graphics and animations, ideas most probably from the book Visualizing Relativity

[@saxtant]

Your explanation is excellent, although you need to be mindful of where the observer is at all times and all events need to be described in relation to a perspective from a certain point within the diagram itself at every stage, one cannot observe the effects as if we can safely refer to any absolute time, every time reference must be relative to another somewhere else, so time doesn't slow down for something falling into a gravity well unless you assume we are observing from outside the well, it's a small, but important distinction that permeates every sentence. On a side note, I believe I have worked out why gravity, not just that gravity is the effect of the curvature, I worked out why the curvature is the shape it is based upon the conservation of angular momentum within Einstein's field equation, if you're interested, I can relate it to you, it provides a reason for the shape of the tensor based up on the careful application of conservation laws and some base postulates from both Newton and Einstein together, I consider it to be the cherry on top of Einstein's field equation, because it explains why an effect like gravity must exist just given the postulates alone, and gravity the same shape does exist according to Einstein and observations.

[@ericzeigler8669]

Why does the universe choose to have mass and light move on geodesic paths? Does it have anything to do with the law of least action?

[@russchadwell]

Question. In this model of spacetime it flares wider as it approaches the center of mass of the earth. But, in another model, spacetime funnels into a point towards the center of mass of something like a black hole.

[@mack_solo]

No. In this model the larger diameter denotes longer time taken to cover the same unit of space. The closer to massive object the slower the time gets. Your second sentence is about spacetime, and is correct.

[@salvatronprime9882]

It's just an inverted visualization, since space and time are represented by perpendicular axes. When discussing the differences of motion through space and/or time, it is helpful to invert the cones in order to show the consistency of the distances travelled.

[@WyFoster]

Gravity is amazing. It isn't a force, it's the bending of space itself. When you're standing on the surface of the earth, gravity isn't pulling you down, the planet's surface is literally accelerating you up at 9.8m/s. It's an extremely difficult thing to wrap your head around, requires an understanding of inertial reference frames, but once you realize it. Mind blowing.

[@kellyem33]

It is described as curvature but is something else. In Einstein’s theory, it is more of a functional analogy

[@Fal-lc9mu]

but shouldn't the cone tighten on the side of gravity?

[@darthex0]

Simply removing mass from directly interacting with other masses, by projecting its effect onto "the fabric of spacetime", does not explain the deflection of a massless photon in a curved spacetime. It just leaves that interaction undefined.

[@tytusmastah]

The cone can work well if a gravity is the only force. I wonder how should air resistance force be put on the cone? Maybe as a force opposite to gravity increasing speed in time direction or maybe air resistance modifies somehow the cone?

[@uweschwarz1760]

There are a few mistakes because of over simplification in this video. For example the ball falling from an infinite high tower would not reach ligthspeed. The potential energy in a gravitational field is finite! So an object with mass cannot reach the speed of light.

[@DABmonger]

Agreed, of course. I wrote the followingI comment ... f the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.

[@ericzeigler8669]

So you're saying the difference in the flow of time between 2 locations is the gradient that drives the apparent force of gravity?

[@mrmoose1599]

Imagine traveling a road that takes 5 minutes to reach your destination. If a sinkhole or crash blocks the path (representing mass in space), you can't continue straight. The obstruction diverts traffic, and you must take a longer route. This detour increases your travel time to 8 minutes. This time dilation reflects changes in spacetime; with increased distance, time dilates. Acceleration also affects spacetime but in a different way. Changing your speed alters the perceived contraction of space and consequently affects the duration of time. Relativity encompasses more than just relationships between measurements. It involves how units of measure change relatively due to different conditions experienced while traveling through spacetime.

[@DABmonger]

Matter tells space-time how to curve, and space-time tells matter how to move. This is because space and time are not flat, but can be warped, stretched, and pulled by matter. Time is relative and not constant. The rate at which time passes depends on your frame of reference. You just need to look at the constant adjustments that have to be made for time dilation to GPS satellites due to Special Relativity (velocity - clocks run slower) and General Relativity (weaker gravitational field - clocks run faster). Overall effect for both GPS satellites and travelling in an aircraft ... clocks tick faster. However, moving at sea level -> clocks run slower, so you age slightly less.

[@wjbkjay23464]

Things that sit around move more through time. Things that race around in motion move more through space. Once again moving fast saves time. : )

[@mrmoose1599]

@@wjbkjay23464 it is just true via formula not reality. Moving at all gives a time but the amount has no value. Nothing can be still so it all moves through time

[@silentminecraftgamer1601]

Nice way to illustrate! :)

[@reidflemingworldstoughestm1394]

Wow. It looks like you could work out the geometry that gravity bends spacetime into by using the acceleration of gravity and that last diagram (6:00).

[@MultiSteveB]

7:09 - I am not a physicist, but I think that is the definition of terminal velocity. "The velocity a free-falling object would reach by the time it struck the surface". It's the same velocity as would take to achieve escape (velocity). On the Earth, that is around 11.186 km/s., not C. Now, from the event horizon of a Black Hole, it would be C.

[@DABmonger]

My comment was: If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.

[@tomasp2899]

But why do you wrap space-time in a cylindrical shape? What physical phenomenon explains this? Some kind of periodicity?

[@xtraspecialj]

I believe it's just a way to visualize it to help understand. It's not a literal interpretation.

[@springerkey6947]

I would like to see an explanation of how "space time" curvature causes the tides. I assume that space time is curved between the moon and the earth ( or between the sun and the earth) and that curvature of space time causes the tides, but I'm having difficulty visualizing how that works.

[@SANN-1969]

2 issues that scientists cannot breakthrough of reverse gravity and to design a shadow, flying object due to objects but the hidden issue is the lights and object mass

[@trevorgwelch7412]

There are 5 levels of time : gravity and acceleration slow time down - in some cases speeds time up 🤓

[@lemongavine]

Wouldn’t Bob be younger since he was moving faster? I could be wrong, but I think you got it backwards. The faster you travel, the slower time goes, right?

[@mack_solo]

They are "moving" at the same space unit per unit of time - the only difference is the influence of gravity. The closer to a massive object the slower the clock.

[@albertorasa6220]

Why does light moves only through time in the flat spacetime diagram wrapped in a cilinder at 3:25? Light does not travel through space only, it also travel through time, its speed is not infinite.

[@KaiVieira-jj7di]

There is no "time" to move through, unless you mean the along the direction of some observer world-line, but you still have to choose such a world-line. That said, yes, light will move equally through the spatial and temporal coordinates of the observer, Δx=Δt.

[@SciD1]

The curvature of space-time is a mathematical abstraction. It's a mathematical description of the effects of gravity. Not an explanation for the cause. Space-time is a mathematical construct, and has no material properties. Space-time is a metric; in physics, a metric is a numerical value derived from measurements, a number, a quantity, to be used in math equations to make accurate predictions. Space-time is a number, a quantity used in the field equations of general relativity, not a material which can bend, curve or warp. Those are figures of speech that refer to the illustrations mapping the gravitational field and its effect on how objects move in that field. No one thinks that the curved lines of isobars drawn on a weather map, or the longitudes and latitudes drawn on a globe map represent anything that is physically real, but when it comes to the space-time metric, the concept has been so thoroughly reified in our imaginations that it almost feels like an attack on our reality narrative to be reminded that it’s only a metric. We even have that absurd phrase, the “fabric of space-time” only because those illustrations are drawn with grid lines that resemble an open weave fabric.

[@DABmonger]

If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.

[@goodwill-y3d]

Why do goose down and a metal ball fall at the same speed in a vacuum? How does gravity determine how much force to apply to objects of different masses so that they fall at the same speed?

[@mrmoose1599]

Gravity is a constant and without air resistance they don’t flutter or slow either

[@billsmith3528]

Gosh I hate it when people put trash on KZbin. Space and time are both metrics and don't create anything. That is the same as saying the measurement of one meter can create life. I hate ignorant people that can not learn basic stuff.

[@paulfogarty7724]

...little confused here. I heard dropping a steel ball from a height & a feather, they'll fall at the same speed ( in a vaccum - no air resisrance ) , and they'll reach a certain speed but won't keep accellerating infinatly towards light speed. I know I must have missed something in your example though.

[@mrmoose1599]

@@paulfogarty7724 they will drop at the same rate and will never reach the speed of light if given the opportunity.

[@mrmoose1599]

@@paulfogarty7724 this is because gravity is constant here but factors act against it like air resistance.

[@DABmonger]

If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.

[@DABmonger]

Matter tells space-time how to curve, and space-time tells matter how to move. This is because space and time are not flat, but can be warped, stretched, and pulled by matter.

[@theblankchannel1752]

Space-time is NOT nothing, it's something that gets curved when influenced by mass... but curved is not the best word to describe what's really happening. The best word is COMPRESSED. And to be exact, only space it's getting compressed, like a sponge. While you're moving with the same speed through compressed space, you are obviously expiercing less time. The interesting thing is to realize the nature of the different quantum fields, their interactions and how they create the gravity (the curvature/compression) in macro space-time, while there is no such phenomena in micro scales.

[@ragnaarminnesota6703]

I understand what you're saying about compressed. If it was compressed, explain the speed of light in compressed spacetime. Try this: The space goes somewhere. It goes into time. Time dilation. Can we balance the books using time?

[@slow-mo_moonbuggy]

​@@ragnaarminnesota6703You can't bend or dialate a concept. Space and time are concepts. Bending a concept is a reification fallacy.

[@ragnaarminnesota6703]

@@slow-mo_moonbuggy Don't say fallacy. Explain. Compress explains. Fallacy does not.

[@slow-mo_moonbuggy]

@@ragnaarminnesota6703 Compress a concept? Can I compress other concepts like love and freedom?

[@StuMas]

The following doesn't make sense to me: How can two people in different timeframes interact? Surely, everything that currently exists, does so in the present moment. If the implication is that the present moment, the now, doesn't exist and everybody is on their own timeline then, wouldn't that render the past and future meaningless? I'm confused.

[@mack_solo]

The same way you can talk to someone of the phone who is at the opposite side of the Earth - there is a delay, because the speed of light (or the maximum speed at which the information can travel) is not infinite, but each one of you remains in your own timeframe. And YES, you are correct - time is relative! That's the whole point of relativity! You're not confused - you've just graduated yourself to a new understanding. CONGRATULATIONS! 😄 🎆

[@DABmonger]

And someone could talk to another person who is higher or lower than them, or is moving faster or slower (perhaps in circles, say). These two people would have different reference frames, but could stay in contact even without a telephone.

[@makantahi3731]

it would be simpler if physicists introduced the term "electromagnetic medium", which transmits electromagnetic radiation in a vacuum,maybe then they would discover where the mass of the universe is hidden

[@brianmason9803]

What force, (force = mass x acceleration) causes the acceleration. The 'rubber sheet' model assumes the object is already moving with respect to the major mass's centre of mass. A static model requires a force to begin acceleration. And more - where does the energy come from to accelerate the object. If an object falls inside a total vacuum calorimeter, it would register heat when the object hits the end of its travel. Where did the energy come from?

[@itheuserfirst3186]

From it's initial creation. Everything in space is falling. An object will stay in motion until acted upon by an opposing force. If an object finds itself roaming space alone, then it will speed up because it's falling.

[@zahajek27]

How much gravitational field/gravitational constant to make light bend?

[@DrDeuteron]

The radius of curvature is c^2/g

[@rodolfosantana9015]

You lost me at ^​@@DrDeuteron

[@DrDeuteron]

@@rodolfosantana9015 well if you imagine a flat earth (no, not like that) and fire a laser beam horizontally, after 186,232 miles it will fall for one second with acceleration "g", so like 16 feet, and that is following curved space time, and (switching to metric) 300 Mm long parabola curved by 5m has a radius of curvature of c^2/g = 10 Pm. (peta meters)..so about 60,000 AU...space is pretty flat around Earth, yet you can't fall 20 feet without getting hurt.

[@O-Kyklop]

@@DrDeuteron Why do Laser beams, in fact, bend upwards when fired parallel to the ground? Indeed fleeing Earth mass.

[@DrDeuteron]

@@O-Kyklop omg. please learn to abstract. We're doing a flat earth model.

[@phillee8666]

I am not a physicist but have a question on this. Light travels in different velocities in different optical mediums. Are we sure there is nothing in the space? Maybe something near the earth has different density that cause light travel slower.

[@mrmoose1599]

@@phillee8666 yes we are sure

[@O-Kyklop]

No,they are not sure. And not only that, they don’t even know if Space is isotropic. Or even worse, they can’t even test it. They only talk and, if you believe it, they don’t need more than that.

[@mrmoose1599]

@@O-Kyklop Yes, on large scales, space is considered isotropic, meaning it looks the same in all directions. This assumption is a key part of the cosmological principle, which suggests that the universe is homogeneous and isotropic when viewed on a sufficiently large scale. This is supported by observations, such as the uniformity of the cosmic microwave background radiation . However, on smaller scales, the distribution of matter (like galaxies and stars) is not perfectly uniform.

[@O-Kyklop]

@@mrmoose1599 Ok. It means you can’t make a prediction for a certain location you can’t check up directly.,……which is most of the Universe. Not a very solid theoretical background, isn’t it?

[@mrmoose1599]

@@O-Kyklop but we can though

[@gregkocher5352]

May I have another? please?

[@Ailsworth]

...and a few years before that, somebody noticed fruit falling... one gets the feeling that our host believes gravity has an independent metaphysical existence, and it is just "out there."

[@4TDsInOneGame]

This is good work Sir…

[@RobouVideos]

This is all taken from another channel @scienceclic

[@comic4relief]

7:03 The iron ball would reach the speed of light? Relative to what? How could the height of the tower be infinite? How long would reaching the speed of light take? How would the speed of the ball be measured?

[@DABmonger]

You would need infinite energy to move a massed object at the speed of light! My comment was: If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.

[@fotograf736]

Good jpb. Now all you need is to connect gravity to electrpmagnetism.

[@solapowsj25]

This is a standard acceptable method to teach the working of gravity, Higgs, and other forces/fields.

[@kennethcole1551]

Gravity makes objects act as though space is curved those are Einsteins words. He also said, for one object, there is no space or time for two Objects you could measure the space between them for two events. You could measure the time between them special time with measurements. They can’t be curved twisted Or bent in anyway.

[@anosonos]

I'm confused now. I thought that if light or any other object travels along the curvature, they would not "feel" any acceleration, i.e. gravitational force and their clocks would tick at the same rate, just as in an inertial frame. Only from the perspective of people on earth, the view of time ticking faster the higher you go becomes plausible. Can someone explain?

[@KaiVieira-jj7di]

You are right. There is no force of gravity and all clocks tick away at the same rate, everywhere, and under all circumstance of motion and orientation.

[@ExistenceUniversity]

There is a real effect called gravitational time dilation. Clocks in a sky scraper tick faster than those on the ground. However, you falling feel no force and your wristwatch is normal to you.

[@KaiVieira-jj7di]

Just to follow up with my previous comment: The differences in elapsed clock time in the presence of gravity is owed to the distances along the clock world-lines (the elapsed proper time) to be different lengths owed to the background curvature.

[@Nikos10]

Isn’t there any length contraction due to the existence of massive objects? Doesn’t this factor contribute to gravity?

[@DABmonger]

Time dilation and length contraction are concepts in special relativity that describe how objects moving at high speeds and/or appear different to a stationary observer. And in general relativity there's gravitational length contraction and gravitational time dilation.

[@_kopcsi_]

no, curved spacetime is NOT the fundamental cause of gravity. it is a model that is able to represent the logic of gravity. but we don't know if spacetime is a real thing. is it useful when we model reality? yes. does it mean it exists? no. exactly relativity proved this when it turned out that gravity is NOT a force. however, in classical (Newtonian) mechanics the concept of force for gravity was extremely useful. so this should be a lesson for us to stay critical and self-reflexive, i.e. to differentiate abstract models from reality. as regards gravity, of course it can be considered as the curvature of spacetime, but this is a too geometrical interpretation which assumes the existence of spacetime which is far from evident. in my opinion, a better definition for gravity can be derived from the generalisations of the concepts of inertia and straight line using non-Euclidian geometry (which are also geometrical concepts, of course, but the existence of inertia is more trivial than the existence of spacetime). thus gravity is nothing but the manifestation of constraint in relation to space and time, which is basically revealed in the rotation of the light cone and thus in the gradual inversion of the roles of space and time.

[@anulearntech]

So gravity is just the side-effect of the curvature or non linear behaviour of Space time, and isn't some force as we see. In fact force is whats needed to behave like we were in a non curved space time while actually being in a curved space-time.

[@babakvelamkon]

Have to watch this 10 times again

[@davidmerritt2383]

🤣 Me Too!

[@paulthebarber42]

According to Newtons law of universal gravation any two masses atract each other. So light must have mass?

[@nikhilgowda6729]

Wonderful explanation thank you 🙏

[@kenanklctepe6550]

What is miles? Something like m/s ?

[@OrlandoMelo-om4zr]

Albert Einstein discovered that space is curved. He opened our eyes to see that traveling to other galaxies is possible, The problem was that we went off course to detonate bombs and kill each other, forgetting the truth about Albert's wish was to teach us that traveling to space is possible without time delaying us to arrive instantly.

[@ragnaarminnesota6703]

We can only travel at 5% the speed of light. At that speed a grain of dust damages the ship a lot. We ain't arriving instantly anywhere.

[@mrmoose1599]

@@OrlandoMelo-om4zr that’s a twisted partially incorrect statement

[@mike42441]

Wait.. at 7:04 you're saying that an iron ball falling infinitely from the Eiffel Tower into a gravitational field would eventually accelerate to the speed of light? Well, problem is, only massless things like photons can travel at light speed, and any object with mass would require energy equivalent to the mass of the entire universe to accelerate to the speed of light, which would also include the mass of the infinitely long Eiffel Tower that the iron ball would be falling next to. So the iron ball would never reach light speed, because if it did it wouldn't be an iron ball anymore, but a stream of photons that used to be the iron ball, the Eiffel Tower, and the rest of the mass of the universe.

[@DABmonger]

Correct. My comment was: If the height of the Eiffel Tower was somehow infinite, the iron ball would reach its terminal velocity, when the force of gravity is perfectly matched by the forces of friction and air resistance. The Eiffel Tower and iron ball would have to be in a vacuum, as well as having an infinite height, for the acceleration to remain. And what's more, an iron ball has mass, and only massless particles can travel at the speed of light.

[@Richinnameonly]

​@@DABmongerthere's more wrong with the example than that but you're missing the point. Dropping any mass onto a black hole would be a better example. By the way if the tower is infinitely tall the ball wouldn't fall at all because it would be too far from the source. Assuming the tower itself doesn't have mass. On another note if there was no ground and the ball was somehow affected by gravity, any air around it would also be in freefall. Terminal velocity only exists if there is a ground for the air to push against, otherwise there isn't any friction of falling.

[@DABmonger]

​@Richinnameonly Me thinks you're overanalysing, and a lot. The creator will giving a simple example, and there is a terminal velocity constraint on Earth, plus nothing with mass can travel at light speed You're adding elements to a simple example, none of which was the creator's intention.

[@troyglover79]

then why do the atomic clocks on satellites travel slower than the ones on the ground? His cone diagram is turned the wrong way

[@DABmonger]

You just need to look at the constant adjustments that have to be made for time dilation to GPS satellites due to SR (velocity - clocks run slower) and GR (weaker gravitational field - clocks run faster). Overall effect for both GPS satellites and travelling in an aircraft ... clocks tick faster. However, moving at sea level -> clocks run slower, so you age slightly less.

[@MarioXP2008]

It´s very interesant, but how explain what in the center or more near to the center of the earth or any kind of mass the "Acceleration" of the gravity go Up, for example in the ecuator the acceleration of gravity are minor, that in the Poles. (You can try it with one simple Pendulum) The first kind of wach... why the acceleration get up, if the time go more slow.... (You catch the contradiction...) acceleration have time to square inside...

[@PetrNekonečný]

We will curve space everywhere. But what is space?

[@tapiopohjalainen3799]

Wrong. In most of our thinking we consider that time is a universal unity, but it is not. A second is valid unit to measure time and a second has the same length at the spesific point of space-time. As you indicate its length is not the same in another location of space-time. Speed is also problematic. In Newtonian world speed is v=s/t. However it is different at different locations in space-time`s 4D world as the time is the 4th D. Take a thinking experiment. In LHC we have two particels A and B. Both are accelerated to a very close speed of ligth and then they colide each other proving there is a God particle, we call it Higgins Boson. Speed is a scalar unit, it is not a vector. We may think as the particles A and B colides they overspeed the speed of ligth. But no. If you are an observer at A particle you think that you are stationary and particle B is approaching at a speed of ligth to you and vice versa. As far as we know the whole universe is on move. A question could be where is the origin of this 4D space-time, it is not existing as speed is a scalar unit. This entaglement of mass-time-gravity cannot be explained until we understand the 4D space-time. Maybe Enistein did and he tried to explain it to earthlings in terms that we comprihend.

[@JustNow42]

Wrong question. Space without time is just compressed. Space is flat not curved like spacetime.

[@Tom-u1o6i]

So if an object "fell" into an object of infinite mass it would achieve near light speed while time would be slowed to next to non existent. Would the masses actually meet, or be caught in a paradox?

[@salvatronprime9882]

It's not really a paradox. Space and time are orthogonal dimensions. Whenever mass or speed reach "infinity" they have actually moved in the orthogonal direction. It could be imagined as a rotation through dimensions preserving angular velocity.

[@andrewbodor4891]

It is matter that slows down, not time. If time dilation is associated with both mass and speed playing a part together, it is the movement or no movemement of mass that creates time dilation. The speed at which mass moves through the aether determines how much time dilation there will be. Mass plus its speed determine how much the time is slowed down. A massive body moving "slowely" can have or create as much time dilation as a small mass moving at extreme speeds. It comes down to how much aether is displaced over a set period of time. A small object traveling at extreme speeds can displace as much aether as s larger mass does that moves slower. In both cases, it is the aether displacement pressing against the mass that causes time dilation and gravity. This pressure, I call gravity. The pressure causes the matter, its true mass, the quarks, to expend energy fighting the pressure and thereby the vibrations of the atomic forces slows down. The atoms experience a slowing down of time, how they "experience" the passing of "time". Time, itself, does not slow down. What does slow down is the matter and how matter reacts to other matter. Computers' functions slow down. The half life of radioactive elements increases. Our brains, our bodies move slower because the matter that makes us, runs slower. We move slower because our cells cannot move any faster. Think of that SiFi movie where the actor moves fast past people who seem to be frozen in place. Each person, all matter, is moving as fast as the matter it or he is made of allows. A big mass moving slow and a smaller mass traveling fast can experience the same amout of time dilation. It is the reaction of mass to the aether and visa versa that controls. A black hole, because of its intense mass and “gravity”, stops all matter from moving; the strong forces are neutralized. The protons, neutrons, electrons, quarks.. become one big mass with NO space between them. Their linearity contracts to nothing. Their mass expands to “infinity”, as measured per volume compared to what it was before being a black hole. Matter traveling at or near the speed of light experiences similar results. There is extreme length contraction; the matter is compressed so there is no room at all between the protons, neutrons, electrons. The mass of the matter is compressed to a small point so that mass per cubic nanometer reaches infinity. Mass per volume increases.

[@TerryUniGeezerPeterson]

So does curved space cause the gravity we experience on Earth, or is it due to the Earth's mass that keeps us from flying off into space?

[@ericzeigler8669]

The Earth isn't really "pulling" us towards the center of the planet. The spacetime stress tensor (an abstract mathematical object) at every point in space is "pushing" us towards the center of the planet.

[@TerryUniGeezerPeterson]

@@ericzeigler8669 Earth's gravity is caused by both the mass of the planet and the curvature of space: Mass The mass of a planet determines its gravitational pull, which is the combined gravitational pull of all its mass on all the mass in your body. This is what gives you weight, and if you were on a planet with less mass than Earth, you would weigh less. Curvature According to Albert Einstein's general theory of relativity, gravity is linked to the curvature of spacetime itself. Massive bodies, like Earth, bend and curve the fabric of the universe, which determines the path that objects travel. This curvature is dynamical, moving as those objects move.

[@ericzeigler8669]

@@TerryUniGeezerPeterson You almost have the correct view. You're mixing Newton into your explanation with this whole "pulling" idea. Einstein's description of gravity has replaced Newton's description in all physic's communities.

[@TerryUniGeezerPeterson]

@@ericzeigler8669 A planet's *mass* determines its gravitational pull, or how strong its gravity is. Gravity is a non-contact force that attracts objects to each other, and *the more mass an object has, the more gravity it has*. For example, Earth's gravity pulls on all the mass in your body, which is what gives you weight. If you were on a planet with less mass than Earth, you would weigh less.

[@O-Kyklop]

@@ericzeigler8669 If Einstein got it right about Gravity, why are we still driving around with gasoline?

[@bUklMusic]

Class video. Will be watching again.