<p>The question itself is wrong, actually.</p>

<p>There is no such thing as absolute velocity, which is what you're assuming in your question. Velocity is always relative to a frame of reference.</p>

<p>Your speed relative to your chair is zero, but it's not zero relative to the airplanes flying over your house.</p>

<p>When you say "a point in space where nothing is moving and velocity is essentially 0", you must add "relative to such-and-such frame of reference", otherwise your statement makes no sense.</p>

<p>By that token, any object in any point of space has zero speed relative to any frame of reference rigidly attached to it, and non-zero speed relative to other frames. You can't talk about speed unless you specify the frame against which it is measured.</p>

<p>Speed doesn't even exist by itself. It's always relative to a frame. It's not a <strong>property</strong> of an object or (even worse) a property of "a point in space". It's a <strong>relation</strong> between an object (the moving thing) and another object (the frame). "Points in space" don't have properties themselves, space is featureless.</p>

<p>Cars may seem like they have a speed as an intrinsic property, but that's just their speed relative to the ground. The car's speed relative to its driver is very different (and hopefully equal to zero). And the car's speed relative to a comet in the Solar System is yet again different.</p>

<p>Any further considerations, such as the flow of time, etc., are invalid as long as you're not asking the right question. Again, speed can only exist relative to something and, as such, it depends on the choice of the frame. And time depends on that whole causal chain.</p>

CC BY-SA 4.0
2018-11-20T11:53:27.557Z
I am strongly disagree with the current science about the idea Florin and I tell you why....
In my point of view there is no fix physical object in space unless if it would be made artificially.
I believe light would give a reference point in this matter to calculate the absolut zero speed in speed as light speed Is constant. Also because speed is relative to time it would also tell us that would be the point where time is running In the absolute fastest in space.
The calculation: We need two laser beam shooted opposite direction
the same time away from each other. Let’s call them X and Y.
The
Attila Varga
CC BY-SA 3.0
2015-03-19T20:22:13.390Z
2015-03-19T20:28:13.390Z
2015-03-19T20:28:13.390Z
Florin Andrei
<p>Yes.</p>

<p>The velocities you list (X, Y, …) are all velocities with respect to some reference frame. But all reference frames are arbitrary, and you can always define a reference frame where the velocity of some object is exactly zero, as long as it's not accelerating.</p>

<p>For instance, Earth's velocity in the Sun's reference frame is X, but in its own reference frame, it's zero.</p>

<p>This is not just semantics; it is probably one of the most profound concepts in physics that there is no such thing as an "absolute frame of reference". Before Einstein, people thought that time and space are absolute, but Einstein taught us that everything is relative.</p>

<p>In cosmology, there <em>is</em> a special reference frame in which all matter <em>on average</em> is zero. The coordinates of this frame are called <em>comoving coordinates</em>, and in many cases it makes sense to regard this as the most natural reference frame. But it is important to remember that it is still just a choice, and that any other reference frame is equally legit, although a bad choice of reference may make certain calculations harder or impossible to solve. In comoving coordinates, the <a href="http://en.wikipedia.org/wiki/Cosmic_microwave_background" rel="nofollow">cosmic microwave background</a> (CMB) is isotropic, i.e. it looks the same no matter which direction you look. But since Earth is traveling with a non-zero velocity in comoving coordinates (at an average of <a href="http://arxiv.org/abs/1303.5087" rel="nofollow">369 km s$^{-1}$</a>), the CMB is slightly blueshifted in the direction in which we're traveling, and slightly redshifted in the other direction.</p>

<p>What would time look like? <a href="http://en.wikipedia.org/wiki/Time_dilation" rel="nofollow">Time runs slower</a>, the faster you move. In any non-accelerating reference frame (an <em>inertial system</em>), time runs "as it should", but an observer in this frame who measures how time runs in a frame that has a non-zero velocity with respect to his/her frame, will see it run slower.</p>

CC BY-SA 3.0
2015-03-16T20:16:25.057Z
To be fair to the pre-Einstein folk, the principle of relativity goes back to Galileo, and *plenty* of people didn't agree with Newton that space was absolute. (And for Newton himself, Galilean invariance of physics is actually a theorem in Principia, but he thought that space must be absolutely anyway for conceptual reasons.) Note that having space relative is enough for the answer to this question to be morally the same, even if time was thought to be absolute.
Stan Liou
CC BY-SA 3.0
2015-03-16T20:23:09.610Z
Yes, you're right. Good points! As for the time stuff, this was an attempt to answer the last part of the question with just a bit more than "It would look like you'd think it would look".
pela
CC BY-SA 3.0
2015-03-19T11:50:31.967Z
600 km/sec is the usual figure for our velocity with respect to CMB: http://apod.nasa.gov/apod/ap140615.html
Wayfaring Stranger
CC BY-SA 3.0
2015-03-19T13:51:11.930Z
Wait, 600 km/s is for the Local Group. I guess we have a non-negligible velocity wrt. this as well.
pela
CC BY-SA 3.0
2015-03-19T14:10:36.263Z
Okay, settled: [369 km/s](http://arxiv.org/abs/1303.5087)! But thanks for prompting me to actually look up the number rather than just guessing :)
pela
CC BY-SA 3.0
2015-03-19T14:28:55.100Z
Oh, cool, @pela. I've been wrong all these years, but now have it straightened out. Thanks.
Wayfaring Stranger
CC BY-SA 3.0
2015-03-19T20:24:00.857Z
The question itself is invalid, because it assumes the concept of absolute speed. As such, it should not be answered. Instead, you should point out that absolute speed does not exist; unless you indicate your frame of reference, talking about speed is meaningless. I've provided that kind of answer below.
Florin Andrei
CC BY-SA 3.0
2015-03-20T11:21:26.590Z
I… I thought that was what I _did_ point out. I don't agree that the question is invalid and should not be answered. I think it's a great question, which gives you and me the opportunity to explain that velocities always should be expressed in relation to something, but that sometimes this "something" is so obvious that we don't need to. Which we did.
pela
CC BY-SA 4.0
2019-09-24T13:00:36.063Z
Wouldn't the point in which the universe "started" be the 0 velocity point? Since after the big bang everything was pushed "away" from it?
Caio Keto
CC BY-SA 4.0
2019-09-24T18:59:15.770Z
@CaioKeto No, the Universe doesn't consist of matter flying away from some point, although this is probably how most people think of it. There is no center of the Universe. There is just space, and this space expands. A good 2D analogy (to a certain degree) of our 3D space is the _surface_ of a balloon being blown up. There is no center _on_ the surface (there is a center inside the ballon, but that's not a part of the surface). No point on the surface is different from any other point, but the distance between all points increases. And any point can be said to be stationary while others move.
pela
CC BY-SA 4.0
2019-09-24T19:03:40.743Z
@pela I guess there isn't a 0 velocity, but if you disconsider the expansion all the matter stills got some velocity right? So the "center" would be a point where the only velocity/acceleration is due to dark energy, it wouldn't have any other forces acting on it, is it right?
Caio Keto
CC BY-SA 4.0
2019-09-24T19:30:42.517Z
@CaioKeto You're right that if you disconsider the expansion, all matter still has a velocity _in that reference frame_. The reference frame is called the "comoving" frame. But that doesn't imply a center, and this doesn't really have anything to do with dark energy or any other type of energy. You're always free to define any reference frame, say the one in which your bicycle is still, and then your bicycle has exactly v=0. If you're cycling, you have v=0 as well, but the traffic light has v$\ne$0. If you park your bike up the traffic light and leave, you have v$\ne$0 while the light has v=0.
pela
CC BY-SA 4.0
2019-09-24T19:31:18.200Z
And the velocity that matter has in the comoving frame is called the "peculiar" velocity.
pela
CC BY-SA 4.0
2019-09-25T11:39:05.067Z
@pela but I mean if you consider the whole universe as the reference frame and disconsider the expansion, will there be a point where someone can go and literally stops? Like, if you could break, in any part I know there will be something pulling you in some direction, but can there be a point where gravity doesn't reach?
Caio Keto
CC BY-SA 4.0
2019-09-25T12:32:42.800Z
@CaioKeto Okay I see what you mean. But no; nowhere does gravity _not_ reach. Gravity decreases with distance, but only asymptotically reaches zero, so you always feel the gravity of everything (though by far it's dominated by the nearest objects). _In principle_, a cosmic conspiracy could result in a point where gravity is exactly balanced: for every particle pulling in _this_ direction, other particles pull in the opposite direction. But not only is the probability of this infinitely small — even if you devised such a universe, particles move so a split second later, there _would_ be gravity
pela
CC BY-SA 3.0
2015-03-16T20:02:18.750Z
2015-03-19T14:12:19.837Z
2015-03-19T14:12:19.837Z
pela
<p>Earth is traveling at a certain velocity.  Earth orbits the Sun at velocity X.  The sun is orbiting the center of our galaxy at velocity Y.  The galaxy is orbiting (something?) at velocity Z. On and on... </p>

<p>In relation to zero, Earth has a velocity of X + Y + Z + (?).</p>

<p>Is it theoretically possible that there would be a point in space where nothing is moving and velocity is essentially 0?  </p>

<p>If so, what would time look like at this point in space?</p>

<special-relativity><velocity>
In theory, is there anywhere in the universe where velocity=0?
Scottie
# In theory, is there anywhere in the universe where velocity=0?

(Asked by: username_0 on 2015-03-16)

Earth is traveling at a certain velocity. Earth orbits the Sun at velocity X. The sun is orbiting the center of our galaxy at velocity Y. The galaxy is orbiting (something?) at velocity Z. On and on...

In relation to zero, Earth has a velocity of X + Y + Z + (?).

Is it theoretically possible that there would be a point in space where nothing is moving and velocity is essentially 0?

If so, what would time look like at this point in space?

**Tags:** special-relativity, velocity

---

## 2 answers

### Answer by username_3 on 2015-03-16. Score: 9 | Accepted answer

Yes.

The velocities you list (X, Y, …) are all velocities with respect to some reference frame. But all reference frames are arbitrary, and you can always define a reference frame where the velocity of some object is exactly zero, as long as it's not accelerating.

For instance, Earth's velocity in the Sun's reference frame is X, but in its own reference frame, it's zero.

This is not just semantics; it is probably one of the most profound concepts in physics that there is no such thing as an "absolute frame of reference". Before Einstein, people thought that time and space are absolute, but Einstein taught us that everything is relative.

In cosmology, there *is* a special reference frame in which all matter *on average* is zero. The coordinates of this frame are called *comoving coordinates*, and in many cases it makes sense to regard this as the most natural reference frame. But it is important to remember that it is still just a choice, and that any other reference frame is equally legit, although a bad choice of reference may make certain calculations harder or impossible to solve. In comoving coordinates, the [cosmic microwave background](http://en.wikipedia.org/wiki/Cosmic_microwave_background) (CMB) is isotropic, i.e. it looks the same no matter which direction you look. But since Earth is traveling with a non-zero velocity in comoving coordinates (at an average of [369 km s$^{-1}$](http://arxiv.org/abs/1303.5087)), the CMB is slightly blueshifted in the direction in which we're traveling, and slightly redshifted in the other direction.

What would time look like? [Time runs slower](http://en.wikipedia.org/wiki/Time_dilation), the faster you move. In any non-accelerating reference frame (an *inertial system*), time runs "as it should", but an observer in this frame who measures how time runs in a frame that has a non-zero velocity with respect to his/her frame, will see it run slower.

> **Comments:**
> **username_4**: To be fair to the pre-Einstein folk, the principle of relativity goes back to Galileo, and *plenty* of people didn't agree with Newton that space was absolute. (And for Newton himself, Galilean invariance of physics is actually a theorem in Principia, but he thought that space must be absolutely anyway for conceptual reasons.) Note that having space relative is enough for the answer to this question to be morally the same, even if time was thought to be absolute.  
> **username_3**: Yes, you're right. Good points! As for the time stuff, this was an attempt to answer the last part of the question with just a bit more than "It would look like you'd think it would look".  
> **username_5**: 600 km/sec is the usual figure for our velocity with respect to CMB: http://apod.nasa.gov/apod/ap140615.html  
> **username_3**: Wait, 600 km/s is for the Local Group. I guess we have a non-negligible velocity wrt. this as well.  
> **username_3**: Okay, settled: [369 km/s](http://arxiv.org/abs/1303.5087)! But thanks for prompting me to actually look up the number rather than just guessing :)  
> **username_5**: Oh, cool, @pela. I've been wrong all these years, but now have it straightened out. Thanks.  
> **username_1**: The question itself is invalid, because it assumes the concept of absolute speed. As such, it should not be answered. Instead, you should point out that absolute speed does not exist; unless you indicate your frame of reference, talking about speed is meaningless. I've provided that kind of answer below.  
> **username_3**: I… I thought that was what I _did_ point out. I don't agree that the question is invalid and should not be answered. I think it's a great question, which gives you and me the opportunity to explain that velocities always should be expressed in relation to something, but that sometimes this "something" is so obvious that we don't need to. Which we did.  
> **username_6**: Wouldn't the point in which the universe "started" be the 0 velocity point? Since after the big bang everything was pushed "away" from it?  
> **username_3**: @CaioKeto No, the Universe doesn't consist of matter flying away from some point, although this is probably how most people think of it. There is no center of the Universe. There is just space, and this space expands. A good 2D analogy (to a certain degree) of our 3D space is the _surface_ of a balloon being blown up. There is no center _on_ the surface (there is a center inside the ballon, but that's not a part of the surface). No point on the surface is different from any other point, but the distance between all points increases. And any point can be said to be stationary while others move.  
> **username_6**: @pela I guess there isn't a 0 velocity, but if you disconsider the expansion all the matter stills got some velocity right? So the "center" would be a point where the only velocity/acceleration is due to dark energy, it wouldn't have any other forces acting on it, is it right?  
> **username_3**: @CaioKeto You're right that if you disconsider the expansion, all matter still has a velocity _in that reference frame_. The reference frame is called the "comoving" frame. But that doesn't imply a center, and this doesn't really have anything to do with dark energy or any other type of energy. You're always free to define any reference frame, say the one in which your bicycle is still, and then your bicycle has exactly v=0. If you're cycling, you have v=0 as well, but the traffic light has v$\ne$0. If you park your bike up the traffic light and leave, you have v$\ne$0 while the light has v=0.  
> **username_3**: And the velocity that matter has in the comoving frame is called the "peculiar" velocity.  
> **username_6**: @pela but I mean if you consider the whole universe as the reference frame and disconsider the expansion, will there be a point where someone can go and literally stops? Like, if you could break, in any part I know there will be something pulling you in some direction, but can there be a point where gravity doesn't reach?  
> **username_3**: @CaioKeto Okay I see what you mean. But no; nowhere does gravity _not_ reach. Gravity decreases with distance, but only asymptotically reaches zero, so you always feel the gravity of everything (though by far it's dominated by the nearest objects). _In principle_, a cosmic conspiracy could result in a point where gravity is exactly balanced: for every particle pulling in _this_ direction, other particles pull in the opposite direction. But not only is the probability of this infinitely small — even if you devised such a universe, particles move so a split second later, there _would_ be gravity  

---

### Answer by username_1 on 2015-03-19. Score: 3

The question itself is wrong, actually.

There is no such thing as absolute velocity, which is what you're assuming in your question. Velocity is always relative to a frame of reference.

Your speed relative to your chair is zero, but it's not zero relative to the airplanes flying over your house.

When you say "a point in space where nothing is moving and velocity is essentially 0", you must add "relative to such-and-such frame of reference", otherwise your statement makes no sense.

By that token, any object in any point of space has zero speed relative to any frame of reference rigidly attached to it, and non-zero speed relative to other frames. You can't talk about speed unless you specify the frame against which it is measured.

Speed doesn't even exist by itself. It's always relative to a frame. It's not a **property** of an object or (even worse) a property of "a point in space". It's a **relation** between an object (the moving thing) and another object (the frame). "Points in space" don't have properties themselves, space is featureless.

Cars may seem like they have a speed as an intrinsic property, but that's just their speed relative to the ground. The car's speed relative to its driver is very different (and hopefully equal to zero). And the car's speed relative to a comet in the Solar System is yet again different.

Any further considerations, such as the flow of time, etc., are invalid as long as you're not asking the right question. Again, speed can only exist relative to something and, as such, it depends on the choice of the frame. And time depends on that whole causal chain.

> **Comments:**
> **username_2**: I am strongly disagree with the current science about the idea Florin and I tell you why.... In my point of view there is no fix physical object in space unless if it would be made artificially. I believe light would give a reference point in this matter to calculate the absolut zero speed in speed as light speed Is constant. Also because speed is relative to time it would also tell us that would be the point where time is running In the absolute fastest in space. The calculation: We need two laser beam shooted opposite direction the same time away from each other. Let’s call them X and Y. The  

---

