Nothing is stationary, Fixed points in space, The possible end of time

[Christian365]

I was thinking earlier today and I thought, how do you define something as stationary? For example, when your car is parked; your speedometer reads 0 kph/mph. But actually because the earth is rotating, technically you're not stationary. Even the earth isin't stationary since it rotates and it also revolves around the sun. And if the big bang theory is true, the sun isin't stationary either since the force from the big bang is propelling all of existence outwards from the original point where the big bang occurred.

Which also leads me to another point, the only fixed point in space is the center of the universe, since everything else is moving.

And it lead me again to another point. If all of existence is moving away from each other gradually, that would mean in the FAR future you will not be able to determine if time is actually passing. Since you can determine time when events are happening. And because everything is moving outwards, all the matter in existence will be extremely spread apart that you won't be able to see anything but the black sea of space. You can't see any stars because they would be SO far that the number of lightyears to determine how far they are from you will be incomprehensible by any type of artificial or living intelligence. Therefore no observable events are taking place.

well, my philosophical side got the best of me. lol. Anyways, what do you think? Also, please try to prove me wrong.

[Relick]

Now I'm no Professor, but I'm pretty sure that everything expanded from the start of the universe - that means there is no centre, nor is there anything at the centre. http://math.ucr.edu/home/baez/physics/Relativity/GR/centre.html read the first paragraph of that for clarification.

Quite frankly, nothing is stationary and getting something to be stationary would require a tremendous amount of work (and energy).

Also intermolecular forces, and especially dark matter will keep things together when it gets further out (leaving aside radioactive decay). The universe will (I believe) split into 'bubble' universes where it has expanded so much that places with nothing appear. Not even space. So yes, you might not be able to see any stars however we can barely see stars further than our own galaxy right now so as long as the galaxy stays in its own bubble you'd still see stars and life would theoretically be possible.

[Christian365]

Now I'm no Professor, but I'm pretty sure that everything expanded from the start of the universe - that means there is no centre, nor is there anything at the centre. http://math.ucr.edu/home/baez/physic...GR/centre.html read the first paragraph of that for clarification.

Nor am I, I'm just a 14 year old :/ anyways, correct me if I'm wrong but, if there is no center, that means there are absolutely no fixed points in space.

Quite frankly, nothing is stationary and getting something to be stationary would require a tremendous amount of work (and energy).

And getting something to be stationary should be impossible. If there are no fixed points in space, that means there will be no reference point to determine if you are actually stationary.

Also intermolecular forces, and especially dark matter will keep things together when it gets further out (leaving aside radioactive decay). The universe will (I believe) split into 'bubble' universes where it has expanded so much that places with nothing appear. Not even space. So yes, you might not be able to see any stars however we can barely see stars further than our own galaxy right now so as long as the galaxy stays in its own bubble you'd still see stars and life would theoretically be possible.

I agree that this statement is theoretically possible as long as the force that keeps a galaxy together will remain for eternity.

Edited April 28, 2013 by Christian365

[Scotius]

Nothing stays forever Even protons have finite life period - although extremely long.

[Awaras]

Nor am I, I'm just a 14 year old :/ anyways, correct me if I'm wrong but, if there is no center, that means there are absolutely no fixed points in space.

And getting something to be stationary should be impossible. If there are no fixed points in space, that means there will be no reference point to determine if you are actually stationary.

I agree that your third statement is theoretically possible as long as the force that keeps a galaxy together will remain for eternity.

You have just stumbled upon one of the central tenets of Einsteins theory of relativity - there is no universal reference point in relation to which something could be stationary. Everything is stationary in relation to something, but moving in relation to something else...

[Xeldrak]

What Anwas said - you can only say that something is stationary in relation to something else. There is no special frame of reference that could be used to say is something is actually moving or not. It's even worse - there is'n even a special time that could be used as the universal time and you subjective time depends on thigs like speed of movement, accelaration or proximity to a gravity well (planets and stuff).

Well, some time ago I read an article about the physics in a very old universe and actually your idea is pretty realistic. But as far as I know, the current theories are even worse: In 100 trillion years star formation ceases - the is just no enough hydrogen and helium to form any new stars, so some time after that the last star burns out. Most Sunsytems will fall into the black hole in the center of their galaxies or will be flung out, so at this point there are no beatiful structures like our milky way left in the universe. In something like 10^34 (a one with 34 zeros behind it) years the nucleons (protons, neutrons) will start to decay, so that soon black holes are the only thing left in the universe. But even they "evaporate" and leave nothing but radiation, so in aproximatly 10^100 (you get it: a one with 100 zeros) years there will be only radiation left On the other hand, maybe our current theories are wrong and we will have a big crunch

[nothke]

I remember that since I've learned about isolated systems in physics classes, I don't think I ever thought about if there are stationary points. I remember that simple example of a person walking inside the train. Relative to the ground , the person moves at 125kmh. but the train moves at 120kmh so he actually walks at 5kmh relative to the train. (taking into account he moves in the direction of the train). If he dropped a ball inside the train, the ball would fall just like it would while stationary, it wouldn't move in relation to the train, but it would move at 120kmh in relation to the ground. So everithing inside the train is an isolated system uninfluenced from the outside (ideally), and the train is a member in the Earth isolated system. That's how the astronauts move at 12000 km/h in orbit in relation to ground but look stationary in relation to spacecraft.

So the whole universe is like a subsystem of subsystems of isolated systems. But that's not true, cause in reality there are no isolated systems, everything influences everything, but IS are just a simplification of how can we humans simplify the universe so we could look at it in relation to something

And since the universe is expanding it is pointless to look for stationary points

Edited April 28, 2013 by nothke

[Stochasty]

I was thinking earlier today and I thought, how do you define something as stationary?

The only fixed point in space is the center of the universe, since everything else is moving.

Not bad for a 14 year old kid.

Of course, physics has moved far beyond these conjectures; there's a heck of a lot we don't know about the Universe, but we do know quite a bit.

For instance - what is the center of the Universe? Everywhere and nowhere. Think of the Universe like the surface of an expanding balloon. From the perspective of a point on the surface of the balloon (any point on the surface), everything else is seen to be moving away. Where is the center of the balloon? Inside the balloon, so no point on the surface can lay claim to being "the center." However, here is where the analogy breaks down; while the Universe is like the surface of the balloon, in that all points move equally away from all other points as the Universe expands, there is no "inside." The Universe is all that exists (nitpickers - save the multiverse debates for another time). Thus, at any given point in the Universe we can look in any direction and see that things are moving in all directions equally away from us - in other words, every single point in the Universe will observe itself to be "the center."

Okay, now that we know where the center is, how do we define "stationary." The case is similar here. Up to certain constraints, we can say that stationary observers are "everyone and no one." I use the word "observers" here because velocity - and thus the concept of "stationary" - depends on whom is doing the measuring. Velocity is not an intrinsic property of the Universe, but rather can only be measured between two objects. For instance, Alice and Bob are both out in spaceships far enough away from everything else that they have no reference points. Alice turns her radar gun on Bob and measures Bob to be moving at 1000 mph. Likewise, Bob turns his radar gun on Alice and measures Alice to be moving at 1000 mph. At this point, a cop pulls both of them over for speeding. When the officer starts to write Bob a ticket, Bob tells him "no sir, I was stationary. Alice was the one that was moving." Likewise, Alice claims that she was stationary, and Bob was the one who was speeding. The officer throws up his hands and turns to Einstein, saying "you figure this one out." Fortunately, Einstein knows the answer - they are both right. Everyone will always measuring themselves to be stationary, and others to be moving around them. Here on Earth, we have a consensus reference point to use that we like to call "the ground" - but that's only because we happen to be living next to something that's large enough and unforgiving enough that it hurts if we smack into it too hard, and thus it makes sense to give the ground pride of place. In space, that's not the case.

Now, I say that everyone will always measure their own velocity to be zero - and this is true - but there is a case where one can, in a sense, measure oneself to be moving. This case is called "acceleration." While velocity is not an intrinsic property of the Universe, acceleration (change in velocity over time) is - and you can always measure your own acceleration. So, that constraint I mention above is exactly this - "stationary" observers (in the sense you mean the term - there is another physics sense, but we won't get into that) are all observers which are undergoing no acceleration - "inertial observers" in the parlance of physics, or "observers in free fall" to use a layman's term.

[Christian365]

Thanks for all the clarifications! I've read all of them and they were very helpful. I'm starting to understand how it really works. After reading them, I have started reading about einstein's theory of relativity for me to further comprehend this topic. Thanks again.

[nettcod]

And if the big bang theory is true, the sun isin't stationary either since the force from the big bang is propelling all of existence outwards from the original point where the big bang occurred.

Actually, the sun doesn't just move outward, but it also revolves around a supermassive black hole at the center of the galaxy called the galactic center.

Edited April 28, 2013 by nettcod

[magnemoe]

You have just stumbled upon one of the central tenets of Einsteins theory of relativity - there is no universal reference point in relation to which something could be stationary. Everything is stationary in relation to something, but moving in relation to something else...

Another relevant question, you can measure the time slowdown because of relativity with an nuclear clock and a jetliner. You should be able to find an vector who gave speed up regarding the vector sun and the galaxy is following.

Yes its teoretical

[WestAir]

The whole "proton decay" thing never really stuck with me. I thought conservation of energy made it impossible for every bit of matter in the Universe to decay and reach its lowest possible energy state. I thought the COE meant that, despite the amount of time that has passed, since the Universe will in of itself always be a closed system, the energy introduced during the big bang will bounce around for eternity.

The theory of universal cold death suggests that the Universe will spread so thin energy can't transfer between particles and every single proton will find itself stuck in its own empty observable universe. I like to think the Universe isn't so horribly designed.

[Dr. Muttonstache]

All of this is relevant to if the big bang theory is correct. Nobody can't say that our existence is a simulation in a computer, whereas none of this would matter. In order for something to be stationary I think you'd need to have a rocket capable of running at the same speed the universe is expanding, pointing exactly toward the center of the universe. I like to think of the universe as a ball. You cant "get out" of the universe, you just rotate around it, like if you ran around a planet. Or, that the universe is like a big game of Asteroids, and you just pop out the other side if you cross it, making parallel universes possible.(like a stack of cards, you'd need to find a way to dig a hole out of the present universe into the other card below you) but thats not the point. Like westair said, energy would last forever in the orb universe, bounce around, and in the Asteroids universe, where it'd just pop out on the other side for eternity.

Like Einsteins theory of relativity - there is no universal reference point in relation to which something could be stationary. Everything is stationary in relation to something, but moving in relation to something else, this means the Universe is moving along other universes, but what are all the other universes moving around, and what is that moving around? AGH MY HEAD HURTS

[Awaras]

Another relevant question, you can measure the time slowdown because of relativity with an nuclear clock and a jetliner. You should be able to find an vector who gave speed up regarding the vector sun and the galaxy is following.

Yes its teoretical

And again, you can only measure the time 'slowdown' (dilation) in relation to something else. If you are in a spaceship moving at relativistic velocities, you will not feel the time slow down - only by looking at something outside your ship (a pulsar for example) will you be able to measure the change in time flow IN RELATION TO THAT OBJECT.

And if you had six ships moving at the same near-lightspeed velocity away from our planet in six different directions, they would all measure exactly the same time dilation in relation to Earth...

Edited April 29, 2013 by Awaras

[K^2]

Nothing stays forever Even protons have finite life period - although extremely long.

Proton decay is a hypothesis. There is absolutely no evidence of it. To the best of our knowledge (Standard Model), protons are perfectly stable.

[hollie.socks]

it's all lies... jks, i'm also 14

[Person012345]

I was thinking earlier today and I thought, how do you define something as stationary? For example, when your car is parked; your speedometer reads 0 kph/mph. But actually because the earth is rotating, technically you're not stationary. Even the earth isin't stationary since it rotates and it also revolves around the sun. And if the big bang theory is true, the sun isin't stationary either since the force from the big bang is propelling all of existence outwards from the original point where the big bang occurred.

Which also leads me to another point, the only fixed point in space is the center of the universe, since everything else is moving.

And it lead me again to another point. If all of existence is moving away from each other gradually, that would mean in the FAR future you will not be able to determine if time is actually passing. Since you can determine time when events are happening. And because everything is moving outwards, all the matter in existence will be extremely spread apart that you won't be able to see anything but the black sea of space. You can't see any stars because they would be SO far that the number of lightyears to determine how far they are from you will be incomprehensible by any type of artificial or living intelligence. Therefore no observable events are taking place.

well, my philosophical side got the best of me. lol. Anyways, what do you think? Also, please try to prove me wrong.

No. There is no "centre of the universe".

Everything is moving away from everything. It doesn't matter where you look everything looks like it's moving from you with you at the centre.

Watch

. It explains pretty much what you're trying to say (although you could still measure time because you still have your local matter cluster, eg. the solar system - such a system is close enough that gravity overpowers the repulsive force).

[Dr. Muttonstache]

No. There is no "centre of the universe".

Everything is moving away from everything..

So what is the universe moving away from? Its creepy Uncle Dave?

[Kerbface]

And again, you can only measure the time 'slowdown' (dilation) in relation to something else. If you are in a spaceship moving at relativistic velocities, you will not feel the time slow down - only by looking at something outside your ship (a pulsar for example) will you be able to measure the change in time flow IN RELATION TO THAT OBJECT.

And if you had six ships moving at the same near-lightspeed velocity away from our planet in six different directions, they would all measure exactly the same time dilation in relation to Earth...

Here's my question... what happens if you have two ships travelling near light speed heading towards each other, just far away enough to miss, how does time dilation affect their relative speed to each other?

And another question. If you fire a laser from Earth and at the same time a ship next to Earth but travelling near-lightspeed in the opposite direction of the laser shoots a different laser in the same direction as the first laser, how does it work that this laser would leave the ship at C relative to the ship, and yet also travel at the same speed relative to Earth as the other laser? Would it? If they were both pointed at the same target (ignoring the fact that the ship would have presumably had to pass through the target to achieve it's speed and trajectory) would they hit it at the same time?

Edited April 29, 2013 by Kerbface

[Stochasty]

how does time dilation affect their relative speed to each other?

Each will measure the other's clock to be moving slowly in comparison with their own.

And another question. If you fire a laser from Earth and at the same time a ship next to Earth but travelling near-lightspeed in the opposite direction of the laser shoots a different laser in the same direction as the first laser, how does it work that this laser would leave the ship at C relative to the ship, and yet also travel at the same speed relative to Earth as the other laser? Would it? If they were both pointed at the same target (ignoring the fact that the ship would have presumably had to pass through the target to achieve it's speed and trajectory) would they hit it at the same time?

Time dilation is what makes this work.

As for "would the hit at the same time?" - Simultaneity is observer dependent in special relativity, so it depends on whom you ask.

Edited April 29, 2013 by Stochasty

[Gniuz]

movement is relative to the object in question, so everything is moving away from everything at a relative velocity.

If you are interested in this sort of stuff I would recommend reading Stephen Hawkins book "A brief history of time". It is a truly interesting book that would help answer a lot of questions like this.

G.

[Kerbface]

Each will measure the other's clock to be moving slowly in comparison with their own.

Time dilation is what makes this work.

As for "would the hit at the same time?" - Simultaneity is observer dependent in special relativity, so it depends on whom you ask.

Yeah, that doesn't really explain much. To someone at the target, would the lasers hit at the same time? To someone on Earth? To the people in the ship? Would someone on Earth see the ship travelling at near lightspeed in one direction and the laser travelling at lightspeed in the other? Or would one or both appear slower as to prevent the total difference being more than the speed of light?

And for the first one I meant how fast would each other appear to be going and... and how is lightspeed different to standing still without a reference point, and if they're both travelling at opposite lightspeeds to say, a speck of dust or other reference point, how is that possible from the perspective of the reference point? Like even right here on Earth (ignoring atmospheric slowing), how do we have light coming or going from 2 directions simulataneously appearing to be at C? Argh. I'm just confusing myself.

Edited April 29, 2013 by Kerbface

[Person012345]

So what is the universe moving away from? Its creepy Uncle Dave?

What?

Things being outside of the universe are hypothesis in their infancy afaik. To say "what is the universe moving away from" does not seem like a sensible thing to say.

If indeed it is sensible, then I don't know. Ask a physicist.

[Gniuz]

The universe isn't moving away from one central point. It is just expanding equally like a balloon when it is filled with air.

In fact that is the best way to think of it. lots of dots on a deflated balloon, the dots move away from each other as you inflate it but it isn't moving away from a central point as such. There isn't one dot that is the centre.

G.

[Kerbface]

The universe isn't moving away from one central point. It is just expanding equally like a balloon when it is filled with air.

In fact that is the best way to think of it. lots of dots on a deflated balloon, the dots move away from each other as you inflate it but it isn't moving away from a central point as such. There isn't one dot that is the centre.

G.

So the Big bang didn't come from a point... it came from everywhere...?