Why Gravity is NOT a Force

9. okt.. 2020
3 643 845 Ganger

The General Theory of Relativity tells us gravity is not a force, gravitational fields don't exist. Objects tend to move on straight paths through curved spacetime. Thanks to Caséta by Lutron for sponsoring this video. Find out more at: www.lutron.com/veritasium
Huge thanks to Prof. Geraint Lewis for hours of consulting on this video so I could get these ideas straight in my own brain. Check out his NOworld channel: ve42.co/gfl or his books: ve42.co/GFLbooks
Amazing VFX, compositing, and editing by Jonny Hyman
2D animations by Ivàn Tello
Filmed by Steven Warren and Raquel Nuno
Special thanks to Petr Lebedev for reviews and script consultation
Music by Jonny Hyman and from Epidemic Sound epidemicsound.com
Rocket made by Goodnight and Co.
Screen images in rocket by Geoff Barrett
Slow motion rocket exhaust footage from Joe Barnard at BPS.Space

  • Here's a question I've seen a lot in comments: OK, I'm accelerating up but then shouldn't someone on the other side of the globe fall off? No, here's why: Either watch again from 8:28 or read what I've written below... Spacetime is curved - it curves the opposite direction on the other side of the Earth. Neither us on this side of the Earth nor they on the other side are changing our spacial coordinates - we're not moving up, they're not moving down - Earth isn't flying into one of us. BUT we both ARE accelerating. In curved spacetime you have to accelerate just to remain stationary. The traditional definition of acceleration is something changing its velocity. In general relativity you have to embrace a new definition of acceleration: it means deviating from a geodesic - not going on a straight line path through spacetime. Near the Earth a geodesic is a parabola so unless you're moving in a parabolic arc (like on a zero-g plane) you are accelerating. This definition is the same as the old one so if you're accelerating in deep space then your velocity is changing. *BUT*... if you are near a large mass you are in curved spacetime, now acceleration your velocity is changing. You can stay stationary relative to Earth's surface and still be accelerating. This is because your acceleration should be measured not relative to the Earth's surface but relative to free-falling objects - they are inertial observers. Imagine this - I'm in deep space and I make horizontal rows and rows of stationary golf balls. Then I hop in my rocket and accelerate up through them. Just think about what that looks like. Now my rocket is back on Earth just sitting there. I freeze time for a sec and make horizontal rows and rows of golf balls up into the atmosphere. Now unfreeze time. What do you see? If you just look at the golf balls and the rocket ship it looks the same as the situation in space where the golf balls were stationary and the rocket was accelerating. Einstein's point was the golf balls have the better claim as the "stationary" thing since their experience is just like the golf balls in deep space - no forces experienced. The rocket on Earth is just like the rocket in space. It feels a force and hence an acceleration.

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  • No, you can't take random maths and warp them to your liking. I put this video with the flat earth theorys

    ross mathisross mathis50 minutter siden
  • Thank you for this video. It challenged my understanding of acceleration. I’m still not sure I understand though - question: When stood on the earth, according to your video (and theory of relativity), we are accelerating. Is this because of the earth’s movement through space? Or because we are not following the curvature of space time geodesic?

    jedidiahjedidiah54 minutter siden
  • At 13.45If you can have a very high speed camera which can shoot with enough fps to capture the motion of a single photon, you will see that all photons are traveling in straight line and that light is not bent. if you are accounting to that fact that the first light photon or particle whatever is that must have moved down, then all the subsequent photons are also moving in a straight line. However, since we cannot normally see light with those fragmented segments of photons we tend or perceive that light(from its initial position till the place it hits an object) is just a single entity of energy which is not composed of multiple smaller photons which is how you can make an assumption that light bends. However in real light in itself is not bending.

    Surya PrakashSurya PrakashTime siden
  • can't wait for flat earthers to find this video, not watch it, and say they have proof of the earth being flat

    ArgoreArgoreTime siden
  • Gravity, an indirect force.

    NeS programNeS programTime siden
  • Also at 5.13, both persons are standing on equator and are ready to walk north. Looking at the longitudes displayed it looks as though both are parallel to each other, however the only place where both longitudes are parallel is right at the exact point where those longitudes meet the equator. You move one step forward or backwards to that single intersection point, you are not perfectly aligned with the longitude in a parallel way, you form a very very small angle between you and the longitude just a step forward or backward from equator. That means if you are walking on the longitude from equator and the person next to you also does that, it means that the moment you made your first step, your direction has changed by some angle which is so negligible that you will not notice it. So its not gravity pulling both of these persons together without a force, it is just that these people have set their destination as North, which is a midpoint to both of these people's location at any point in time, so obviously they would move closer to each other

    Surya PrakashSurya PrakashTime siden
    • I'd love you to correct me if I'm wrong

      Surya PrakashSurya PrakashTime siden
  • At 4:50 where you show the plane flying, the earth's axis of rotation changed midway before planed landed at B giving the path traveled by plane more curvature. Can you rotate the earth with just one axis and show that the path is still curved? Also, when you say the path is curved, arent you talking about the path in a 3 axes plane and not a 2 axes plane? If its a 3 axes plane then you might want to show that the path looks straight in a 2 axes plane and instead of cutting the globe and making it into a map, bring in the new 3rd axis and show that the path is curved within the 3rd axis

    Surya PrakashSurya PrakashTime siden
  • Sure to give my answer! If you think of two objects holded in your hands and you are there with no other object both the objects are not moving in your view. then, what could be the reason for both mass to move toward each other because by this theory object needs to be in velocity to cause effects of curve of spacetime

    Abhay KumarAbhay KumarTime siden
  • Interesting

    Beyleh MusicBeyleh MusicTime siden
  • Gravity *is* a field. Namely the field is the metric tensor and its Lagrangian is the Ricci curvature scalar. Your "acceleration" argument is misleading because the terms in the equation are manifestly dependent on the reference frame, and thus not physical. You'd have to express it in terms of the entire 4-acceleration, not just one component of it.

    Salvador VillarrealSalvador Villarreal2 timer siden
  • Why is there then so much interest in finding a theory of everything that combines gravity with the other fundamental forces, if gravity is not a force? There is need for a theory of everything then.

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  • rip rocket man 0:00 - 4:10

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  • @rtensor but the river is flowing due to gravity, making your analogy nothing more than a useless circular definition.

    Rýán TúçkRýán Túçk2 timer siden
  • Regardless of views of the video. The most pleasant video I ever watched on NOworld.

    Ridwan Amin ShuvoRidwan Amin Shuvo2 timer siden
  • this is the best video on entire youtube, period.

    01_abdulmateen.pitodia01_abdulmateen.pitodia2 timer siden
  • If this is true, can you explain why the moon effects the ocean tides?

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  • So what is a graviton then?

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  • i lost and gained brain cells

    Fahmy HusseinFahmy Hussein2 timer siden
  • Classical Gravity = 4th Newton's Law. Let the polemic begins.

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  • The only, problem with this video, is that people who already don’t understand how the world works, just heard you say the earth is flat. You didn’t say anything about the shape of the earth, but they will hear “accelerating up”, “gravity isn’t a force”, “light bends”, and finally misunderstand your entire video, and suddenly you’re Flat Earth famous.

  • So many people are now able to understand "Gravity", thanks to the way these explanations have been given. 😊👍🏻

  • Gravity is God's gift to us

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  • General relativity requires changing the rules of math and physics. Only a cosmologist can get away with ignoring long standing principles in order to force a desired outcome.

    Mark AndersonMark Anderson3 timer siden
  • After watching this all I have is more questions. What about gasses? Are they travelling faster than the speed we are travelling? How are objects not falling off the planet that are on the opposite side of the planet? Shouldn't the planet accelerate away from them if they were thrown up? And is there a difference in object "weight" on different parts on earth?

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  • Gonna have to watch this a few more times i think! Couple of comments though: 1. @~10:50. Physists often try and use maths as a proof of things. The reality is maths is an entirely human construct. It doesn't prove ANYTHING. The universe is unaware of maths and doesn't care about it much less follow it. 2. @~15:00. It is often said that general relativity has passed every test so far. Well what about this whole problem of dark matter/energy?

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  • Away from a mass, in flat space, how does the deviation from geodesic look when i start the engine?

    Chris DomvilleChris Domville3 timer siden
  • How do you explain the orbital motion of planets around the sun if gravity is not a force?

    Aakash PatelAakash Patel4 timer siden
  • Great work ♥️

    Andrew ZacostaAndrew Zacosta4 timer siden
  • Curved space time? That's unlikely, space is infinite, and always expanding, assuming that space is just straight lines is like saying that paper can fold through itself without tearing.

    DaiemioDaiemio4 timer siden
  • Sorry but I disagree, a person on one side of the planet is not accelerating away from a person on the opposite side of the planet, I do have a more logical theory and that is the force that makes planets round is the same force that makes atoms round, and that is a force that is pushing equally on all sides forcing it to become a ball, one logical explanation would be space is not a vacuum but actually full of infinitely small particles (small enough to force a atom into a perfect ball) thus we are actually getting pushed onto the earths surface, this also explains why 2 planets would be attracted to each other as this compressed energy is everywhere and is trying to force the 2 planets to merge and become one single ball

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  • If you wear weights and sink down in water you would feel somewhat similar to falling off a building. Could you then be a halfway inertial observer in water?

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  • relativity is so selfish

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  • Finally the Earth is flat.

    MrXxyMrXxy4 timer siden
  • Help me out here... around 3:30, as the rocket bends ever-so-slightly towards the planet, why wouldn't spaceman's experience become ever-so-slightly non-inertial? As his rocket changed direction (ie accelerated) around him, wouldn't he himself continue in a straight line and find himself bumping into one of the walls? Or as it sped up, getting faster and faster, into the floor? How can we say he would remain oblivious to his newly accelerating frame of reference?

    Michael HrycenkoMichael Hrycenko5 timer siden
  • Could a sixth grader not understand 45% of the vid?

    Please Enter A NamePlease Enter A Name5 timer siden
  • Earth is a spaceship and its the only one we've got..!

    Ruhaan GuptaRuhaan Gupta5 timer siden
  • Imagine some people think, that videos like these and even all science books, articles, lectures... are all just a conspiracy to let us believe, that the earth is flat 😂😂😂

    silagonkillaxsilagonkillax5 timer siden
  • TLDR: gravity is an illusion of curved space time

    Breezy BeeBreezy Bee5 timer siden
  • "Very interesting. But... noworld.info/video/video/lHTOlp-Z2s_gpJo.html

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  • How gravitational curving starts? The higher the mass the higher is curvature, so what come first? Electrostatic forces? also what about gravitons the wave propagating through space, can there be resonances and standing waves? Would in this case matter interact with this phenomena?

    Mykola IvanchenkoMykola Ivanchenko6 timer siden
  • That is right, it isn't, gravity is a shape and entropy is a flux, the man isn't falling from the roof, the air just appears to be going up while the man goes down because he has more mass than the air, just like when oil floats in the water, a drop of water on top of it would appear to fall inside and merge together with the rest of the water, when you feel you weight is not that you are just accelerating, your mass wants to blend with the other mass that weights the same inside the entropy field, that is the reason why you fall slower inside the poll, because the water's mass is heavier than the air, if it was even heavier than your mass it would be like the water is falling around you while you appear to float upwards

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  • Well you've convinced me

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  • Then why are we trying to find gravitron in quantum standard model

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  • Does it also mean the closer to the center of mass the curvature is higher, thus acceleration to stay at the same point must be higher, thus time mast go slower? Or if you are out of any center of mass the time must flow faster?

    Mykola IvanchenkoMykola Ivanchenko6 timer siden
  • I don't see how they could acurately pass tests on deflection of light by gravity. When your goal is to establish the light of a star at a different position in space then any margin of error could also be deemed as proof of light being deflected by gravity. There are so many variables to take in account to accurately calculate this. And you can never know if the star is really out of position due to gravity or an error in the calculation of it's actual position.

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  • Flat earthers have left the chat.

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  • There's a flaw in the theory at 13:12. The light beam would not deflect down while the ship would speed up as the photons from the laser are carrying the same kenetic energy as the spaceship in which it's being transmitted. You could compare this by dropping a ball in a speeding train. Within the train the ball will travel straight down and hit the floor exactly below it. It will NOT deflect slightly towards the back of the train as your theory suggests. From an external observer point of view the ball would have traveled a considerable distance relative to his own position but that same observer would also see the ball hit the exact same mark on the floor of the train. If you were to replace the laser in the spaceship with a paintball gun and place a camera to study the path of the balls you would see the balls traveling in a straight line because they move in the same direction and velocity as the spaceship.

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  • Are you SURE that space suit is properly NASA certified?

    Lennart RegebroLennart Regebro7 timer siden
  • I don't think that that the gloves you are wearing will protect you in a low pressure environment. They will blow up and become useless.

    Vlad SnapeVlad Snape7 timer siden
  • AMAZING !!!!!!!!!

    Coco the CoconutCoco the Coconut7 timer siden
  • 🤯💨

    MaximDerPandaMaximDerPanda8 timer siden
  • Can you explain the force in a black hole?

    Tristin VandammeTristin Vandamme8 timer siden
  • Ok I get it. Everything in space moves uniformly in a straight line. When you get near a big object, say the earth, the curvature of spacetime makes the line bend towards it. Now suppose for a second you wouldn't crash into the earth's surface at that velocity, but instead just get stuck against it. Relative to your normal inertial path which would take you through earth, you are now being accelerated upwards. Stuck against the earth's surface like you're stuck against a magnet. Only a sufficient amount of thrust can get you out of that inertial path and into a new one.

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  • I suppose this explains gravitational potential energy, too, then.

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  • It is 2020 and we still have grown adults believing in space. LOLZ

    BruceBruce8 timer siden
  • Absolutely Amazing Man!! I just started loving physics as a high school student as I saw your video!!

    Sukritya AthwalSukritya Athwal8 timer siden
  • So why do giant masses bend spacetime?

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    • what is happening if you move really fast ?

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  • Who else is more confused after watching this video?

    Gaurav DeshmukhGaurav Deshmukh8 timer siden
  • Anyone who's ever done a Bungy jump will tell you the sensation is not weightlessness but stunning acceleration.

    Edward ReidEdward Reid9 timer siden
  • After watching both this video and Vsauce’s video I think I understand everything except why massive objects like planets curve space time.

    Tim LewisTim Lewis9 timer siden
  • Funny stuff...desperate stuff. 'Gravity' ....just none. No 'Gravity' at all. No 'Gravitational Wavs' either.

    Ashley LawAshley Law9 timer siden
  • But doesn't time not exist either?

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  • We lost VSauce, but God's grace got us here

    Mihir AgasheMihir Agashe10 timer siden
  • If some how we ejected 1% of the earths mass into space we would only be accelerating up at 9.702 mps2

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  • if you are in rest in earth's frame of reference then the then the freely falling proton creates magnetic field. if you are freely falling on earth then a stationary(according to earth) proton will create magnetic field. proton or a current carrying wire creating magnetic field is the example of general relative theory

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  • then why the heck the teacher gives example of force as *Gravitational force*

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  • Every time someone makes a comment about the beginning of the universe, They always start by saying "in the beginning there was a gravity field which attracted something else and then we had a big bang". I always wonder what existed before the gravity field? If you can imagine a gravity field then you should be able to imagine where it came from. I can easily imagine nothing but space, just empty space no time no gravity no mass nothing. How can so many come along and say we had mass and gravity when they cant explain where they came from?.

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  • mn i give u a like jst for the FKING preety good sound quality, like, just fking kidding me? outside d spaceshipt, inside it, IN earth... i mean,... im just very high now but u deserve it

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  • So, if we remove gravity from the equation. You could effectivley walk on the surface of a black hole if you were an inertial observer. It would not be gravity that would crush you, but spacetime shrinking to an infinatley small point?

    Michael FranklinMichael Franklin11 timer siden
    • black holes have no surface

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  • Bruh....... When we fall, the world that's comes to us to make us at the rest position

    Diky SahertianDiky Sahertian11 timer siden
  • 10:05 "Shouldn't the Earth by expanding?" "No" "Why? Because 'math'..."

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    • Honestly, if GR didn't have other independent predictions that have been proven correct, I think it'd just be a bunch of clever math. That Einstein took that one equivalence principle/thought experiment and just went nuts with it, but that it didn't actually apply to reality. However, its independent predictions have indeed been proven correct.

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  • I’ve seen this claimed so many times, but it’s not true. All objects on Earth do not fall at the same rate. Your formula is missing m2. Objects fall at a rate of the ratio of each mass compared to Earth. While the ratios are a very small difference the principle that all objects fall at the same rate is false. If 2 objects the size of bowling balls were dropped at the same time but one had the mass of the moon they would not impact the Earth at the same time.

    Jeff KissingerJeff Kissinger12 timer siden
  • Why are they looking for the graviton particle? If its not a force then there shouldn't be a force giving particle?

    Darragh FinnanDarragh Finnan12 timer siden
  • If massive objects creates space time curvature. I believe that every objects has their own curve spacetime too, it defends on the mass. What if the massive object like Earth is not accelerating but smaller mass objects and the Earth is pushing each other. The more massive objects, the more stronger push against bigger mass ( like Earth which is the center of mass of our world itself). Human has lesser mass than elephant so that it would feel heavier than us. All smaller objects around Earth including humans are pushing against Earth while Earth push upward everything around smaller mass object. In that case, no need acceleration just to feel our weight.

    Brod FeetBrod Feet12 timer siden
  • this video is like those scientists talking about blackholes. they know 0 about them but pretend to know something hahahahahahaha

    Lee AndrewLee Andrew13 timer siden
  • The flat earthers are going to clip the hell out of this and then call it proof

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  • Yes it is.

    Paul RoutledgePaul Routledge13 timer siden
  • ....... um what o.0

    Cindy DahlCindy Dahl13 timer siden
  • I can't connect gravity waves and gravitons to this idea. Any advice on reconciling these things?

    Michael HunterMichael Hunter13 timer siden
  • Awesome ending thought experiment, it was very profound and instructive.

    Simon WuSimon Wu13 timer siden
  • its not, you hitting the earth. its was the earth that hit you!, BAD earth, bad earth!

    Dev RifterDev Rifter13 timer siden
  • @veritasium If gravity is illusion then what is the theory behind blackholes

    Harsh AnvekarHarsh Anvekar13 timer siden
  • How is that rocket goes faster and faster 3:30 and inside he feels as constant velocity ?

    pavan sughoshpavan sughosh13 timer siden
    • To follow up : 4:25 he fees he is moving on constant velocity

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  • That's my first thought too when I see someone falling from a building....."Oh look, someone inertly observing my acceleration through spacetime."

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  • This episode makes me think of an episode of Futurama, where the professor was talking about the ships new cutting edge engines. He stated that the engines don't push the ship through space, but the ship remains stationary, and the engines push space away from the ship, thus "propelling" the ship to its destination.

    Marc JohnsonMarc Johnson14 timer siden
  • This guy makes so much efforts to make the videos that he went to space. We should support him👍

    Shashwat JoshiShashwat Joshi14 timer siden
  • There is no science in this video.

    GLobDeliGLobDeli14 timer siden
  • So really all you've proven is that gravity is not a force TO AN INERTIAL OBSERVER. Which doesn't seem too profound to me. I mean, that's kind of the whole point of gravity, man. It's all relative. Reality is subjective, not objective. You confuse symbols for their meanings.

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  • 17:00 another thing is you can manually turn off the light and still use the hub to turn it on

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  • Anyone remember the Buzzard with Bugs Bunny. This guy is the Buzzard noworld.info/video/video/kIesZ96Np9zM2Jo.html Yup Looney Tunes

    sam clemenssam clemens14 timer siden
  • Saying this, how did early space navigation circumvent this issue? How did the inertial guidance track properly? Interesting.

    damonlandsdowndamonlandsdown14 timer siden
  • My kids will love this silly video.

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  • My understanding is that they proved "gravity" waves are real which is the ripples in space time of which you speak of

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    • You believe that nonsense?

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  • Ok... whoa... this different perspective might just be blowing my mind. You're telling me I don't fall onto the Earth. The force of the Earth is pulling me back to the planet, because of "speed force"? Hmmm?

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    • @Doopliss77 OK. So, you're telling me that's what happens when I jump off a roof? The Earth accelerates towards me? How? What if I'm in the opposite direction of the revolution?

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    • Let us say you were inside an elevator and it is going up. You decide to jump while it is moving up. After you jump you do not fall down to the elevator, the elevator accelerated into your feet.

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  • If I start falling I think I'm going to feel a "force". Minutes into this video... I still don't grasp gravity. I feel like this one theory is something that's explained to us and we say, "OH that's how it works", but we have no clue from our own understanding. Well in this moment my own understanding.

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  • Ok so gravity does not exist. I can see the point but in noworld.info/video/video/zKLNmN-FuaqqlJI.html why are there gravitational waves if there is no such thing? We need to stop calling this gravity as we say this doesn't exit but say it does by calling it "gravitational". Maybe we need to just stop using the word gravity and start calling it something else entirely.

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  • Could anyone further explain what happens at terminal velocity?

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  • Up is not down except for the upside down people.

    Jerry CrowJerry Crow15 timer siden
  • if you were accelerating while standing still you would be gaining energy, because that is what acceleration is, it is adding net energy to an object.....after accelerating in place as you put it, you would gain mass according to relativity, which is why you can not accelerate to the speed of light because you would aquire infinite mass before you reached C. Your arquement is symantic in nature and not based in fact.

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