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### Author Topic: Is relativistic velocity a noticeable effect?  (Read 12676 times)

#### damocles

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##### Is relativistic velocity a noticeable effect?
« Reply #25 on: 03/10/2011 22:30:53 »
Yes Damocles, it has been proved. What i don't know it is if the reverse frame experience has been done.

A simple experience would be to synchronize two atomic clocks on earth. An astronaut takes one of the clock on the International Space Station. A year later, an astronaut takes the other clock to the space station and compares their time. After separating the effects of general relativity and special relativity, what is the effect of special relativity?

The problem with this is that general relativity is probably far more complex and less well-established than special relativity; if any anomaly were found in this experiment, which theory would it challenge? Or perhaps it would challenge neither, but a hidden assumption that the effects of the two theories could be separated and combined in an additive fashion?

A traveling tiny mass (relatively of dominant mass) has a slowed time, this is proved.
A traveling dominant mass (relatively of tiny mass) has a slowed time, this is not proved!

mass does not enter into the treatment of time dilation in special relativity; there does not seem to be a need to treat these two cases separately, and it goes against ockham's razor to find any real need to do so. (We would never say, for example, that it has been proved for Tuesdays but not for Fridays).

#### yor_on

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##### Is relativistic velocity a noticeable effect?
« Reply #26 on: 03/10/2011 22:45:05 »
As I see it special relativity is about light speed and treat the universe from there. General relativity is the description of gravity, linking it to lights speed in a vacuum. And they are not separate, in reality both goes together, everywhere.
==

It's not that mysterious if you accept that we have one constant 'c' that defines a border. that border will be the exact same in Einsteins definition, no matter your (relative) speed or 'gravity'. The next step he did was to in cooperate 'gravity' into it. He realized that 'gravity' not only was a expression from invariant mass, but also from accelerations, and as I think of it, also from the geometry of space. He then linked those descriptions into SpaceTime where 'time' is a definition having two faces. One 'invariant locally', never changing its pace. and one defined from the 'time dilations' we observe comparing our 'invariant time pace' to other 'frames of reference', as a speeding spaceship. Gravity is in his descriptions a form of acceleration, in that it can produce the same 'time dilation' as a acceleration. The really tricky part, to me that is, is to see how different 'relative uniform motions' can produce time dilations on their own, relative a observer. And that one still hurts my head, sometimes it feels as if I can see why, but then it moves away from me again :).. But it has to be right, although the universe would look simpler to me if it was only gravitation/mass and accelerations that produced it.

Take a look here.
clocks so accurate that they lose or gain less than one second every 3.7 billion years.

But please ignore the Mail Online statement that you 'gain a longer life span'. That's so phreakin 'not it' that I almost want to write them a angry letter :) you only gain a 'longer life' relative the 'universe', but counting your heartbeats they will deliver you the same wherever you are, and measuring them against your wrist watch they will be the exact same. That one seems to be the most common misunderstanding of Einsteins theory of relativity there is.
« Last Edit: 03/10/2011 23:14:31 by yor_on »

#### JP

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##### Is relativistic velocity a noticeable effect?
« Reply #27 on: 03/10/2011 23:11:52 »
As I see it special relativity is about light speed and treat the universe from there. General relativity is the description of gravity, linking it to lights speed in a vacuum. And they are not separate, in reality both goes together, everywhere.

Special relativity is one special, simple case of general relativity.  General relativity is about comparing observations between observers undergoing arbitrary accelerations (or in the presence of gravitational fields, which are equivalent to accelerations).  GR does this by modeling space-time as curved.

Special relativity is what you get when space-time isn't curved (no gravity/accelerations between observers) or when you only care about a tiny region of space-time (very small volume of space in a very short time) in which case the curved space-time looks pretty much flat.

They both postulate the speed of light being constant.  GR needs more postulates about gravity and accelerations.

#### yor_on

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##### Is relativistic velocity a noticeable effect?
« Reply #28 on: 03/10/2011 23:16:34 »
Well JP, I will stand by my definitions.

By the way NIST Pair of Aluminum Atomic Clocks Reveal Einstein's Relativity at a Personal Scale This one is the source of the link I gave above. And what it says should help you understand what a 'time dilation' really is. You need to consider that if you were there you would see those clocks desynchronize in front of your eyes. If you at the same time measured your heartbeats against your wrist watch you would find it to be 'invariant', no matter if you laid on the floor, or stood up while observing those clocks.

A 'time dilation' will always be a description between frames of reference, but nowhere will it influence your own 'intrinsic/inherent' time flow. You don't age 'slower' (although you you will see the universe 'speed up'.) by staying in a gravity well as a neutronstar, or laying close to the Earths surface, you have only one 'life span' of heartbeats, whatever. It's quite simple.

=

Dam*, this one was harder to write than I thought :)
« Last Edit: 04/10/2011 00:21:05 by yor_on »

#### MikeS

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##### Is relativistic velocity a noticeable effect?
« Reply #29 on: 04/10/2011 08:31:32 »
As I see it special relativity is about light speed and treat the universe from there. General relativity is the description of gravity, linking it to lights speed in a vacuum. And they are not separate, in reality both goes together, everywhere.
==

It's not that mysterious if you accept that we have one constant 'c' that defines a border. that border will be the exact same in Einsteins definition, no matter your (relative) speed or 'gravity'. The next step he did was to in cooperate 'gravity' into it. He realized that 'gravity' not only was a expression from invariant mass, but also from accelerations, and as I think of it, also from the geometry of space. He then linked those descriptions into SpaceTime where 'time' is a definition having two faces. One 'invariant locally', never changing its pace. and one defined from the 'time dilations' we observe comparing our 'invariant time pace' to other 'frames of reference', as a speeding spaceship. Gravity is in his descriptions a form of acceleration, in that it can produce the same 'time dilation' as a acceleration. The really tricky part, to me that is, is to see how different 'relative uniform motions' can produce time dilations on their own, relative a observer. And that one still hurts my head, sometimes it feels as if I can see why, but then it moves away from me again :).. But it has to be right, although the universe would look simpler to me if it was only gravitation/mass and accelerations that produced it.

This is my take on the cause.

Why is gravity the same as acceleration and why are the effects of this the same as traveling near to the speed of light?

1)   Why is gravity the same as acceleration?
All mass creates a gravitational field.
The field is stronger on the surface of the Earth (mass) weakening further away.
A gravitational field dilates time.
Time dilation is greatest on the surface of the Earth with the passage of time becoming faster the greater the distance.
Acceleration contains a time factor.  Therefore, changing the passage of time (time contraction) is the same as an acceleration.
Mass, by continually moving from a state of high time dilation to low time dilation is continually accelerating (in space-time).  This is an affect of gravity.

2)   Why is traveling (at a constant velocity) near to the speed of light the same as acceleration?
To accelerate to any speed that is an appreciable fraction of the speed of light
requires a large amount of energy.  The energy goes toward infinity as the
speed of light is approached.  Due to energy equivalence E = mc2 mass also
tends toward the infinite.   So even if the object is not accelerating but is
traveling at a significant fraction of the speed of light then it has enough mass
to produce a gravitational field and this is equivalent to acceleration.

#### simplified

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##### Is relativistic velocity a noticeable effect?
« Reply #30 on: 04/10/2011 14:34:43 »

mass does not enter into the treatment of time dilation in special relativity; there does not seem to be a need to treat these two cases separately, and it goes against ockham's razor to find any real need to do so. (We would never say, for example, that it has been proved for Tuesdays but not for Fridays).
[/quote]Day of result of clever experiment will be a holiday of science.
Illegibility is not a science.

#### yor_on

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##### Is relativistic velocity a noticeable effect?
« Reply #31 on: 15/10/2011 03:06:55 »
Well Mike, gravity do dilate 'time'. To Einstein this was about 'frames of reference' and how to define a same time for a 'frame'. The idea was to have some defined distance, and then send a light pulse from the exact middle of that distance to its endpoints, where you would have two 'clocks' getting synchronized, as I understands it. That would give a same 'frame of reference' time-wise, relative the clocks.

Another way, that I'm fond of, is to define all 'frames of reference' as slightly different. And as those atomic clocks showed, there most probably is no point in a positional system with the same values, when you count up all the values defining them, as position, gravity/mass, relative motion, and so 'time'.

If we only discuss gravity, I think the same will be applicable, although you then can have two 'points' defined to be the same, even if not positionally, as we can manipulate gravity by accelerations, and just kismet, sort of.

But the reason gravity dilate time seems to be the same reason accelerations do, and that reason must hinge together with 'c' and the way a 'room time geometry' get distorted with motions. So Einstein defined two types of 'accelerations', one as in motion, another as in invariant mass.

« Last Edit: 15/10/2011 06:05:12 by yor_on »

#### simplified

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##### Is relativistic velocity a noticeable effect?
« Reply #32 on: 16/10/2011 06:48:49 »
Does the same acceleration make traveler be younger(relatively of motionless twin) after long travel than after short travel?If the same acceleration does different results then what is main cause of slowing of time?
« Last Edit: 16/10/2011 10:07:27 by simplified »

#### Pmb

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##### Is relativistic velocity a noticeable effect?
« Reply #33 on: 20/10/2011 16:41:00 »
The further a galaxy is away from us the faster it is receding and there is no limit on that speed. Galaxies can be observed which are moving away from us faster the speed of light. And this does not violate the 1st postulate of relativity.

As to the question Relativistic mass increase at slow speeds, Gerald Gabrielse, Am. J. Phys. 63(6), June 1995

I can e-mail that to anyone who wishes to read it, or I culd temporarily post it somewhere on my website for your viewing pleasure. :)

Best wishes

Pete

#### damocles

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##### Is relativistic velocity a noticeable effect?
« Reply #34 on: 20/10/2011 18:29:19 »
...(snip)...Galaxies can be observed which are moving away from us faster the speed of light. ...(snip)...

Umm... there is a problem here, at the very least a semantic one. I would not have been fazed by "... There is evidence for the existence of galaxies which ...", But "...Galaxies can be observed which ..." is surely impossible by definition! For something "to be observed", light from some part of the em spectrum must have left it and reached us or our instrument to be detected, because that is the basic definition of "observed". If an object is receding from us faster than the speed of light, how could that possibly happen?

#### imatfaal

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##### Is relativistic velocity a noticeable effect?
« Reply #35 on: 21/10/2011 13:36:16 »

...(snip)...Galaxies can be observed which are moving away from us faster the speed of light. ...(snip)...

Umm... there is a problem here, at the very least a semantic one. I would not have been fazed by "... There is evidence for the existence of galaxies which ...", But "...Galaxies can be observed which ..." is surely impossible by definition! For something "to be observed", light from some part of the em spectrum must have left it and reached us or our instrument to be detected, because that is the basic definition of "observed". If an object is receding from us faster than the speed of light, how could that possibly happen?

Agree - there exist gaps between galaxies that according to our theories are increasing faster than light speed.  The furthest we can observe is the CMB and the distance to that is not increasing at above light speed.

#### damocles

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##### Is relativistic velocity a noticeable effect?
« Reply #36 on: 21/10/2011 14:59:55 »
But I wonder if that can work. Because if I see object A moving South at speed 0.9c and object B moving North at 0.8c, then special relativity tells us that their relative speed is not vA +vB, but vA + vB - vA.vB/c2

That is, they are moving apart not at 1.7c but at 1.7 - 0.72 = 0.98c

#### JP

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##### Is relativistic velocity a noticeable effect?
« Reply #37 on: 21/10/2011 15:14:04 »
There's 2 reasons why it can happen.

First, special relativity tells you that the space between objects can't increase at faster than the speed of light, but in special relativity, space itself is static.  In general relativity, nothing in static space can move apart faster than the speed of light, but if space itself is expanding, they can.

Think of it as two ants on the surface of a balloon.  Each ant has a built in speed limit--the fastest it's legs can move.  If the balloon isn't being inflated, they can move apart at some maximal speed determined by their individual maximal speeds.  If you inflate the balloon while they're moving apart, the space between them increases at faster than the rate they'd expect just based on their own maximal speeds--because the balloon itself has expanded.  But if they look down at the patch of balloon right below them, they're still moving over it at their maximal speed.  Similarly, nothing can move over a small patch of space faster than the speed of light, but over large regions, the expansion of space can cause things to move apart faster than the speed of light.

Second, the light reaching us from distant galaxies is light they emitted a while ago.  If they are receding at faster than the speed of light, then light they're emitting now will never reach us--they've gone beyond the visible horizon of the universe.

#### MikeS

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##### Is relativistic velocity a noticeable effect?
« Reply #38 on: 22/10/2011 06:59:12 »
What does the creation of space mean?  What is it that is being created?

#### simplified

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##### Is relativistic velocity a noticeable effect?
« Reply #39 on: 23/10/2011 18:22:10 »
What does the creation of space mean?  What is it that is being created?
The space is totality of distances. Distance  is ability of reduction and increasing .
« Last Edit: 23/10/2011 18:46:49 by simplified »

#### simplified

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##### Is relativistic velocity a noticeable effect?
« Reply #40 on: 23/10/2011 18:41:37 »
I would say that if we look at a clock that "moves" away from us at speed 0.5 c, because of expansion of space, and a clock that moves away from us at speed 0.5 c, then we see the clock that "moves" is running faster than the clock that moves.

Because: "moving" can reach speeds like 5 c, while moving is always slower than 1 c.

If we look at a galaxy that is "moving" at speed 0.9 c, and moving at zero speed, then we see no Lorentz contraction in the galaxy. Or do we see?

I don't see. Gravitation of our galaxy does not make kinematic slowing of time of such very far galaxy.
« Last Edit: 23/10/2011 18:43:19 by simplified »

#### damocles

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##### Is relativistic velocity a noticeable effect?
« Reply #41 on: 23/10/2011 23:30:27 »
I would say that if we look at a clock that "moves" away from us at speed 0.5 c, because of expansion of space, and a clock that moves away from us at speed 0.5 c, then we see the clock that "moves" is running faster than the clock that moves.

Because: "moving" can reach speeds like 5 c, while moving is always slower than 1 c.

If we look at a galaxy that is "moving" at speed 0.9 c, and moving at zero speed, then we see no Lorentz contraction in the galaxy. Or do we see?

I don't see. Gravitation of our galaxy does not make kinematic slowing of time of such very far galaxy.

It is important to remember that the Lorentz contraction is a 1-dimensional thing: it applies only in the direction of motion: towards or away. It is also the case that our observation of the extent of something is a two-dimensional thing: we can observe up, down, left, right, but not towards, away. So we have no means of directly observing whether the contraction applies or not (to the component of motion directly away from us) when we look at distant galaxies. The two dimensions of observation and the one dimension of contraction are orthogonal.
« Last Edit: 23/10/2011 23:33:23 by damocles »

#### jartza

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##### Is relativistic velocity a noticeable effect?
« Reply #42 on: 24/10/2011 11:29:57 »
I would say that if we look at a clock that "moves" away from us at speed 0.5 c, because of expansion of space, and a clock that moves away from us at speed 0.5 c, then we see the clock that "moves" is running faster than the clock that moves.

Because: "moving" can reach speeds like 5 c, while moving is always slower than 1 c.

If we look at a galaxy that is "moving" at speed 0.9 c, and moving at zero speed, then we see no Lorentz contraction in the galaxy. Or do we see?

I don't see. Gravitation of our galaxy does not make kinematic slowing of time of such very far galaxy.

It is important to remember that the Lorentz contraction is a 1-dimensional thing: it applies only in the direction of motion: towards or away. It is also the case that our observation of the extent of something is a two-dimensional thing: we can observe up, down, left, right, but not towards, away. So we have no means of directly observing whether the contraction applies or not (to the component of motion directly away from us) when we look at distant galaxies. The two dimensions of observation and the one dimension of contraction are orthogonal.

I was thinking about a large mirror to help us see what the side of a receding galaxy looks like.

But now I can see that universe is transparent enough, so we can see that receding galaxies are not packed together in the towards-away dimension.

#### damocles

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##### Is relativistic velocity a noticeable effect?
« Reply #43 on: 24/10/2011 13:11:01 »
Perhaps I am partly blind, but I do not "see" any way we can know about the towards, away dimension of a distant object by direct observation if we are unable to change our position. Even the normal artist's rules of perspective are not really knowing, because they make assumptions about the shapes of the objects we are looking at. How can we possibly "see" that distant galaxies are not packed close together in layers (apart from different red shifts, etc,, which is again making assumptions)?

#### simplified

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##### Is relativistic velocity a noticeable effect?
« Reply #44 on: 24/10/2011 14:53:38 »
I would say that if we look at a clock that "moves" away from us at speed 0.5 c, because of expansion of space, and a clock that moves away from us at speed 0.5 c, then we see the clock that "moves" is running faster than the clock that moves.

Because: "moving" can reach speeds like 5 c, while moving is always slower than 1 c.

If we look at a galaxy that is "moving" at speed 0.9 c, and moving at zero speed, then we see no Lorentz contraction in the galaxy. Or do we see?

I don't see. Gravitation of our galaxy does not make kinematic slowing of time of such very far galaxy.

It is important to remember that the Lorentz contraction is a 1-dimensional thing: it applies only in the direction of motion: towards or away. It is also the case that our observation of the extent of something is a two-dimensional thing: we can observe up, down, left, right, but not towards, away. So we have no means of directly observing whether the contraction applies or not (to the component of motion directly away from us) when we look at distant galaxies. The two dimensions of observation and the one dimension of contraction are orthogonal.

I was thinking about a large mirror to help us see what the side of a receding galaxy looks like.

But now I can see that universe is transparent enough, so we can see that receding galaxies are not packed together in the towards-away dimension.
Very interesting idea. If speed reduces distance then the farthest galaxies are ten times closer.
Relativity is ridiculous theory.

#### Pmb

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##### Is relativistic velocity a noticeable effect?
« Reply #45 on: 24/10/2011 18:13:29 »
Quote from: damocles
[...(snip)...Galaxies can be observed which are moving away from us faster the speed of light. ...(snip)...
It's well known among Astro physicists that there is an event horizon, which means that galaxies exist beyond that horizon. Galaxies which are closer to the horizon can be observed.
« Last Edit: 24/10/2011 18:15:59 by Pmb »

#### JP

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##### Is relativistic velocity a noticeable effect?
« Reply #46 on: 25/10/2011 00:53:29 »
Relativity is ridiculous theory.

Fortunately for Einstein's ghost, it's better than the even more ridiculous alternatives!

#### thebrain13

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##### Is relativistic velocity a noticeable effect?
« Reply #47 on: 25/10/2011 06:27:42 »
I pretty much just spent all day thinking about relativity in an attempt to logically explain why the math works.

To my surprise I was able to do it using different logic and math. I just thought I'd show how the end of it worked out. (1/2(c+v)(c-v)+1/2(c-v)(c+v))=1/d^2 If you solve for d, you get the correct equation for time dilation(woo hoo!)

However I'd like to point out, my logic is a bit "etherian" if you will. The logic I used is based on the idea that time dilation is dependent on an observers motion relative to its surroundings compared to another objects motion relative to the other objects surroundings. So if there was an object traveling 3 times the speed of light in an area where everything travels 3 times the speed of light, and you were at rest relative to your surroundings, there would be no time dilation between you and the distant speedy object.

#### simplified

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##### Is relativistic velocity a noticeable effect?
« Reply #48 on: 26/10/2011 19:25:12 »
Relativity is ridiculous theory.

Fortunately for Einstein's ghost, it's better than the even more ridiculous alternatives!
Relativity convinces people to not make some  useful experiments. Therefore it is less ridiculous but  more dangerous for development.

#### JP

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##### Is relativistic velocity a noticeable effect?
« Reply #49 on: 26/10/2011 20:29:52 »
Relativity is ridiculous theory.

Fortunately for Einstein's ghost, it's better than the even more ridiculous alternatives!
Relativity convinces people to not make some  useful experiments. Therefore it is less ridiculous but  more dangerous for development.

On the contrary, it prevents people from wasting time with ridiculous experiments, thus freeing them up to make scientific progress.  Relativity has been supported by so much experimental and observational evidence that it's definitely a highly accurate model, even if it turns out to only be approximately correct.

By the way, when experiments are done that seem to rigorously show that relativity might have a problem, they're taken very seriously, as is evident from the recent faster-than-light neutrino result.

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##### Is relativistic velocity a noticeable effect?
« Reply #49 on: 26/10/2011 20:29:52 »