Do you understand Space/Time Relativity?

[K3NS31]

Interesting problem with wormholes, some scientists are now theorising that it's impossible to "have travelled" faster than the speed of light. So u can't go in one side of a wormhole, and come out the other side at a distance greater than light could've taken to do the same trip. Because then you as soon as you appear on the other side, you've effectively travelled faster than light. This may still violate Relativity.

As to the OP, as far as I understand, you can move so fast that time travels slower for you, but that's still not time travel. You cannot get information back to earth about events before they've happened. Hence, no. No time travel. sorry.

Edit: there are actual physicists on the forums who can explain this properly. Guys...?

 

[scotty777]

Interesting problem with wormholes, some scientists are now theorising that it's impossible to "have travelled" faster than the speed of light. So u can't go in one side of a wormhole, and come out the other side at a distance greater than light could've taken to do the same trip. Because then you as soon as you appear on the other side, you've effectively travelled faster than light. This may still violate Relativity.

As to the OP, as far as I understand, you can move so fast that time travels slower for you, but that's still not time travel. You cannot get information back to earth about events before they've happened. Hence, no. No time travel. sorry.

Edit: there are actual physicists on the forums who can explain this properly. Guys...?

Um, well, the thing with wormholes is that they aren't violating relativity... you aren't actually going faster than the speed of light, just taking a short cut.

Think of it this way. You having a race, which is one big loop, now, you create a short cut, which means you pop out at the finish line sooner than light can travel around the race track. Your speed could be a couple meters per second, which means you aren't violating anything! That's the whole idea behind the wormhole. You warping space to create a short cut.

I'm not a physicist though, so my understanding of relativity is pretty rudimentary. (I'm taking a 1/2 year course in physics - relativity + quantum )

 

[Techne]

This is using the view that spacetime arises due to the interaction of particles, which I feel is the theory that has the most going for it.

I am interested on your view about time.
A) Do you think time exists as some sort of entity on its own?
B) Do you think time is the result of change (for example the interaction of particles)?

From the above I presume it is B, just want to make sure.

I suppose I can take the question further and ask whether:
A) Do you think the universe is a 4D object or block whereby everything is composed of spatial and temporal parts and these parts just get added as time parts increase (or time progress if you want)?
B) Do you think that 3D objects with spatial parts move through time?
C) Do you think that change (the interactions of substances or particles if you want) gives rise to space-time but substances do not have temporal parts, only spatial parts?

 

[fastesthamster]

The forum ate my reply. Have to retype *grumble*. It's never as good the second time

I am interested on your view about time.
A) Do you think time exists as some sort of entity on its own?
B) Do you think time is the result of change (for example the interaction of particles)?

From the above I presume it is B, just want to make sure.

Yes, I would go with B. Without change there is no time, without more than 1 particle there is no distance. Time as an entity on it's own makes about as much sense to me as distance as an entity on it's own. This is the most parsimonious explanation for what time is.

I suppose I can take the question further and ask whether:
A) Do you think the universe is a 4D object or block whereby everything is composed of spatial and temporal parts and these parts just get added as time parts increase (or time progress if you want)?
B) Do you think that 3D objects with spatial parts move through time?
C) Do you think that change (the interactions of substances or particles if you want) gives rise to space-time but substances do not have temporal parts, only spatial parts?

a) Indeed, you can view the universe as a 4D block, and then your velocity will yield different slices through the block. This is why observers in one reference frame will disagree on what events are simultaneous, they have different slices through this (abstract) 4D block. See the relativity of simultaneity for more.

b) Yes, if they are interacting with other objects, or they are undergoing change in themselves.

c) Well, not quite. This is what we were discussing in the other thread (which I have not forgotten btw, I just need a rest!). As Paul Davies puts it, '[Electrons are] not so much a physical thing as an abstract encodement of a set of potentialities'. I think this is similar to the potentia you mentioned. The potentiality, or substance as you put it, will only have a temporal part if we can measure the change it is undergoing, or if it interacts with other substances. Similarly it will only have a spatial part if there are other substances to compare it to.
So it's not a question of having only temporal parts, or only spatial parts. Both are only measurements of the substance. The spatial aspect is not more special than the temporal aspect, although perhaps it is easier to conceptualise a timeless state than it is to conceptualise a spaceless state?

 

[K3NS31]

Um, well, the thing with wormholes is that they aren't violating relativity... you aren't actually going faster than the speed of light, just taking a short cut.

Think of it this way. You having a race, which is one big loop, now, you create a short cut, which means you pop out at the finish line sooner than light can travel around the race track. Your speed could be a couple meters per second, which means you aren't violating anything! That's the whole idea behind the wormhole. You warping space to create a short cut.

snip...

Yes, I get that. That's why we all like Wormhole theory so much, cos you can travel great distances quickly without "violating relativity". BUT that's what this physicist was talking about in the article I read (can't remember where, might've been Popular Science) - basically they think that even though you're taking a shortcut at "slow" speed, because you'd come out on the other side having covered a great distance at effectively faster than light, the shortcut itself may still be impossible. Yeah, doesn't make sense, but that's theoretical physics for you.
Still, the point is it would suck if they're right

 

[SoulTax]

Yes, I get that. That's why we all like Wormhole theory so much, cos you can travel great distances quickly without "violating relativity". BUT that's what this physicist was talking about in the article I read (can't remember where, might've been Popular Science) - basically they think that even though you're taking a shortcut at "slow" speed, because you'd come out on the other side having covered a great distance at effectively faster than light, the shortcut itself may still be impossible. Yeah, doesn't make sense, but that's theoretical physics for you.
Still, the point is it would suck if they're right

Can anyone post a good link regarding immense gravity actually being able to compress time itself? I understand Space being warped and compressed by gravity, but is there any empirical proof of gravity effecting time? Or is it simply theory that if gravity effects space, and it is thought that space-time is one joint concept, that gravity affects time by virtue of affecting space.

 

[K3NS31]

Can anyone post a good link regarding immense gravity actually being able to compress time itself? I understand Space being warped and compressed by gravity, but is there any empirical proof of gravity effecting time? Or is it simply theory that if gravity effects space, and it is thought that space-time is one joint concept, that gravity affects time by virtue of affecting space.

Just Google "Einstein" or Theory of Relativity and settle in for some heavy reading.

 

[SoulTax]

Just Google "Einstein" or Theory of Relativity and settle in for some heavy reading.

Ye I have read a lot of it a few times over the years. Its the kind of heavy reading that requires a constant refresher read if you dont actively work with it every day. I am talking more about some study and experiment done between the 1940's and now, that empirically proves that time is effected by gravity.

Anyway my point is actually this: If a gravitational field could dilate time, does that mean that it changes the rate at which our bodies age as well? So would someone identical to myself live longer if they were travelling really fast all the time, because time would be slowed down for them? Or is the body's aging process relative to itself and not time around it. Therefore would this "clone" simply consciously experience time at a slower pace to me, but still age at the same pace physically, or would the aging process be slowed, relative to the time dilation, from my relative point of view?

 

[scotty777]

Ye I have read a lot of it a few times over the years. Its the kind of heavy reading that requires a constant refresher read if you dont actively work with it every day. I am talking more about some study and experiment done between the 1940's and now, that empirically proves that time is effected by gravity.

Anyway my point is actually this: If a gravitational field could dilate time, does that mean that it changes the rate at which our bodies age as well? So would someone identical to myself live longer if they were travelling really fast all the time, because time would be slowed down for them? Or is the body's aging process relative to itself and not time around it. Therefore would this "clone" simply consciously experience time at a slower pace to me, but still age at the same pace physically, or would the aging process be slowed, relative to the time dilation, from my relative point of view?

It's called the twin paradox... look it up.

In essence, the faster you go, the more your clock slows down, in every sense. So basically, if you moving at 99% of the speed of light, then time will slow down by a factor of 7.08 times!
What this means it that if one second passed for you, 7.08 seconds will pass to everyone else! thus, if you went at that speed for one year on a round journey then when back home, you will have aged one year, and everyone else would have aged by 7 years!

Gravity has also been 'confused' with acceleration... However, what happens with gravity, is that you get something of a massive 'hole' forming in the fabric of space-time... The moon revolving around the earth isn't really what it seems to be... The moon is actually traveling in a straight line, only, the earths gravitational field has 'buckled' space-time to a point where a straight line actually is going around the earth...

This holds true for light as well, because light only travels in a straight line, but when it passed a large mass, such as a star, it 'bends' around the star, but it's actually not bending, it's literally space-time that is warping and becoming a bending straight line. If it's hard to conceptualize, well, think of it as you sailing around the world... It looks like you going in a dead straight line, but you are in fact traveling around on a curved path, due to the curvature of the earth!

Gravity also compresses space and time as it gets stronger. GPS systems need to take into account for the fact that there's no acceleration acting on them, which means if manufacturers didn't take into account that the GPS satellites clock wasn't running faster than the clocks on earth (because on earth, we are experiencing a new gravitational field), then the clocks would be ineffective after the first day!

When gravity reins supreme and gets so powerful because mass is so dense, not even light can escape. Basically, this is a black hole. It's not a literal hole, but rather a gravity well, where nothing can escape. When light gets to close, the straight line it was going in encompasses the blackhole, and then it's fscked and won't be able to leave . ha ha.

One of the weirder things is that when two objects are approaching each other, at say, 0.6 times the speed of light, their relative speed is actually 88.2% the speed of light!

I also forgot to mention that even mass increases when you go faster and faster...
So, as you approach the speed of light, you're mass increases! If you were traveling at 99% of the speed of light, then you'll relativity weigh 7.08 times more than you would at rest! This means that your kinetic energy gained is actually going into mass, which describes how interlinked mass and energy are. It's fundamental to remember that Energy and mass are actually interchangeable terms in modern physics.
This is why something with mass can't go faster than the speed of light, because your mass goes to infinity, which means you need an infinite amount of energy to move you at that speed, and so the universe itself is holding you back .

 

[SoulTax]

It's called the twin paradox... look it up.

In essence, the faster you go, the more your clock slows down, in every sense. So basically, if you moving at 99% of the speed of light, then time will slow down by a factor of 7.08 times!
What this means it that if one second passed for you, 7.08 seconds will pass to everyone else! thus, if you went at that speed for one year on a round journey then when back home, you will have aged one year, and everyone else would have aged by 7 years!

Gravity has also been 'confused' with acceleration... However, what happens with gravity, is that you get something of a massive 'hole' forming in the fabric of space-time... The moon revolving around the earth isn't really what it seems to be... The moon is actually traveling in a straight line, only, the earths gravitational field has 'buckled' space-time to a point where a straight line actually is going around the earth...

This holds true for light as well, because light only travels in a straight line, but when it passed a large mass, such as a star, it 'bends' around the star, but it's actually not bending, it's literally space-time that is warping and becoming a bending straight line. If it's hard to conceptualize, well, think of it as you sailing around the world... It looks like you going in a dead straight line, but you are in fact traveling around on a curved path, due to the curvature of the earth!

Gravity also compresses space and time as it gets stronger. GPS systems need to take into account for the fact that there's no acceleration acting on them, which means if manufacturers didn't take into account that the GPS satellites clock wasn't running faster than the clocks on earth (because on earth, we are experiencing a new gravitational field), then the clocks would be ineffective after the first day!

When gravity reins supreme and gets so powerful because mass is so dense, not even light can escape. Basically, this is a black hole. It's not a literal hole, but rather a gravity well, where nothing can escape. When light gets to close, the straight line it was going in encompasses the blackhole, and then it's fscked and won't be able to leave . ha ha.

One of the weirder things is that when two objects are approaching each other, at say, 0.6 times the speed of light, their relative speed is actually 88.2% the speed of light!

I also forgot to mention that even mass increases when you go faster and faster...
So, as you approach the speed of light, you're mass increases! If you were traveling at 99% of the speed of light, then you'll relativity weigh 7.08 times more than you would at rest! This means that your kinetic energy gained is actually going into mass, which describes how interlinked mass and energy are. It's fundamental to remember that Energy and mass are actually interchangeable terms in modern physics.
This is why something with mass can't go faster than the speed of light, because your mass goes to infinity, which means you need an infinite amount of energy to move you at that speed, and so the universe itself is holding you back .

Cool, I knew some of the specifics in there although the 7.08 and the twin paradox is new to me. Nice breakdown though. I will research the twin paradox, its not one of the things I have come accross in my limited google searches, thanks for the direction. Its always been one of those topics that i have found all my info from the Nat Geo or Discovery programs. I suppose I should spend a bit more time on the reading side.

 

[K3NS31]

snip...
This is why something with mass can't go faster than the speed of light, because your mass goes to infinity, which means you need an infinite amount of energy to move you at that speed, and so the universe itself is holding you back .

Nice explanation, thanks.
Now where were you when those idiots in that thread a few weeks ago were trying to say it's possible to go faster than light?

 

[Archer]

Can anyone post a good link regarding immense gravity actually being able to compress time itself? I understand Space being warped and compressed by gravity, but is there any empirical proof of gravity effecting time? Or is it simply theory that if gravity effects space, and it is thought that space-time is one joint concept, that gravity affects time by virtue of affecting space.

Empirical proof. I already linked it in an earlier post. Basically they used atomic clocks. One was at sea level (more gravity) and the other was higher up (less gravity) and after a set period they showed different times. Hence gravity based time dilation is proven. Think they've repeated the experiment in space as well.

 

[Jabberwocky]

One of the weirder things is that when two objects are approaching each other, at say, 0.6 times the speed of light, their relative speed is actually 88.2% the speed of light!

I don`t understand this.

 

[SoulTax]

Empirical proof. I already linked it in an earlier post. Basically they used atomic clocks. One was at sea level (more gravity) and the other was higher up (less gravity) and after a set period they showed different times. Hence gravity based time dilation is proven. Think they've repeated the experiment in space as well.

Ye true, I have heard of this experiment before, I have just always been too lazy to research how an atomic clock works. Not knowing how it works has always left me wondering how they can be sure that it would maintain a perfect "Sea level" second regardless of movement etc... same with speed. But once again I suppose I just need to research some of those things that have been niggling on my mind, with regards to this experiment.
A little reading will help to set my uncertainties at ease.

 

[Archer]

Ye true, I have heard of this experiment before, I have just always been too lazy to research how an atomic clock works. Not knowing how it works has always left me wondering how they can be sure that it would maintain a perfect "Sea level" second regardless of movement etc... same with speed. But once again I suppose I just need to research some of those things that have been niggling on my mind, with regards to this experiment.
A little reading will help to set my uncertainties at ease.

Each element emits a very specific frequency when changing energy levels. That is then used as the basis for the clock (as opposed to a crystal in most watches). Hence very accurate, especially if cooled to near 0°.

Most recently

In 2010 gravitational time dilation was measured at the Earth's surface with a height difference of only one meter, using optical atomic clocks

Pretty easy to maintain two objects only 1m apart

 

[SoulTax]

Each element emits a very specific frequency when changing energy levels. That is then used as the basis for the clock (as opposed to a crystal in most watches). Hence very accurate, especially if cooled to near 0°.

Most recently

Pretty easy to maintain two objects only 1m apart

Pretty cool actually. So theoretically someone living at 2km above sea level will live longer than an identical person living at sea level. If all other things are equal; nutrition, disease, oxygen, exercise, etc....

 

[LazyLion]

all I know is that there are eddies in the space/time continuum!

 

[scotty777]

I don`t understand this.

Oh, that's a tough one to get your mind around... buuut I'll do my best to explain the effects at play... This is all pretty much why Einstein got a lot of sex back in the day .

Ok, now, as per spacial relativity, nothing can go faster than the speed of light relative to another object... It's impossible, well, at least the maths tells us it's physically impossible! So in order to approach this problem, lets say we have a third particle in the middle of these two objects moving towards each other...

Now, if each object was traveling at 0.6c (I'll use this is say 0.6 times the speed of light), then the particle would see the object to it's left moving at 0.6c, and the particle to it's right moving at 0.6c.

Now, if we want to work out what speed the other object is moving at, you must punch it into a formula, that's pretty tricky to figure out what's cutting, but when you do, you soon realize that due to time dilation, the objects see the other object actually covering less distance than itself! It's really not something easy to conceptualize... but that's how it works sadly.

Since nothing can go faster than the speed of light, relative to something else, this is why these consequences happen... Because of relativity, the laws of physics are all conserved in all inertial frames.

The other difficult this to conceptualize is that if I was traveling at 0.999999999 times the speed of light in my car, and I turned on the head lights of my car, the light will actually move away from me at the speed of light if I were to measure it... The light will also move at the speed of light to an observer. So the speed of light is constant in all inertial frames too!

 

[Archer]

Since nothing can go faster than the speed of light

One correction - nothing with mass can travel faster than light...

 

[Jabberwocky]

Oh, that's a tough one to get your mind around... buuut I'll do my best to explain the effects at play... This is all pretty much why Einstein got a lot of sex back in the day .

Ok, now, as per spacial relativity, nothing can go faster than the speed of light relative to another object... It's impossible, well, at least the maths tells us it's physically impossible! So in order to approach this problem, lets say we have a third particle in the middle of these two objects moving towards each other...

Now, if each object was traveling at 0.6c (I'll use this is say 0.6 times the speed of light), then the particle would see the object to it's left moving at 0.6c, and the particle to it's right moving at 0.6c.

Now, if we want to work out what speed the other object is moving at, you must punch it into a formula, that's pretty tricky to figure out what's cutting, but when you do, you soon realize that due to time dilation, the objects see the other object actually covering less distance than itself! It's really not something easy to conceptualize... but that's how it works sadly.

Since nothing can go faster than the speed of light, relative to something else, this is why these consequences happen... Because of relativity, the laws of physics are all conserved in all inertial frames.

The other difficult this to conceptualize is that if I was traveling at 0.999999999 times the speed of light in my car, and I turned on the head lights of my car, the light will actually move away from me at the speed of light if I were to measure it... The light will also move at the speed of light to an observer. So the speed of light is constant in all inertial frames too!

Thanks,
I think i understand now.
Because the two particles are moving fast, their time is passing slower. Therefore, if you were sitting on the particle, the other one would approach you at a slower rate than it would look like to an outside observer.
Though.. to an outside observer they would approach each other at 1.2c, But that is not cheating relativity because nothing is moving faster than light relative to him.