A space travelers mass

[asprung]

I have been told the the length of the molecules and the size of the spaces between them actually shortens. This is an event, not a measurment,which should be viewed by all observers when it occurs, though they may differ as to the time.

[Klaynos]

They don't change in their own rest frame though.

[asprung]

How can there be an actual physical change yet no change at all? Even if the process is reversed the change had occured and cannot be erased.

[iNow]

The change occurs only from the perspective at the person looking at them, not the thing they are looking at. The thing they are looking at doesn't experience change.

 

This is where the idea of "frame of reference" comes in.

 

The object is one frame of reference.

The person measureing the object is a different frame of reference.

 

They each see different things.

[swansont]

However, the use of "see" does not mean that this is an illusion. Using the same measurement techniques, observers in different frames will measure different values.

[iNow]

Ah... Isn't that always what happens when you try to convey something using overly simplistic terms.

 

Thanks man. Important clarification, indeed.

[asprung]

Is there a structureal change or only the illusion of a structual change to certain observeres.

[Klaynos]

Is there a structureal change or only the illusion of a structual change to certain observeres.

 

This implies an absolute reference frame, which doesn't exist, so the change is therefore real and not an illusion.

[swansont]

But there is no structural change. Length is different, time is different, depending on which frame you are in.

[asprung]

If there is no structual change it really does not happen. Only measurments change. On the other hand I have been told above that the shape actually distorts.

[swansont]

If there is no structual change it really does not happen. Only measurments change. On the other hand I have been told above that the shape actually distorts.

 

The shape distorts, depending on your frame of reference.

 

You have a meter stick. An observer who is moving relative to you, measures it as being a "0.9-meter stick." There is no structural change to the stick. It is not an illusion (a trick of the eye), since you can use identical measuring techniques.

 

Neither of you can prove who is right about the length of the stick, since both of your reference frames are equally valid. So, is the stick really a meter long?

[asprung]

I would think that the space traveler’s time frame would determine weather there was any structural change as opposed to a measurement change as that is the time frame he is in. While he may appear flat to certain observers he is really not so as to harm him physically.

 

I get confused and can only conclude that it is always “now” and things are as they are “now”

[thedarkshade]

If the space travelers is length contracted his body would become distorted. I dont know why I cant ask if this really happens. He only has one body,and something really happens to it or doesnt.

Why distorted? It would just 'shrink' (contract) with respect to the velocity it is traveling with. You can even calculate it yourself using Lorentz contraction.

[swansont]

I would think that the space traveler’s time frame would determine weather there was any structural change as opposed to a measurement change as that is the time frame he is in. While he may appear flat to certain observers he is really not so as to harm him physically.

 

I get confused and can only conclude that it is always “now” and things are as they are “now”

 

He doesn't see himself as flattened, but another observer does. Who is right?

 

The problem is that neither of the two can establish that their view is the correct one.

[pioneer]

There is a simple way to demonstrate that relative reference violates the conservation energy and creates a modern perpetual motion machine. I can do it with a simple thought experiment.

 

Here is the scenario. We launch a rocket from the earth until it reaches relativistic velocity. Based on the near C speed and the energy added, we calculate that the relativistic mass has doubled. We also set up ten stationary observation posts to view the rocket from many angles. If reference was relative, the moving reference would see relativistic mass increases at all ten stations, or tens times as much energy as we actually put into the rocket, i.e., each stationary reference should appear the same, right. Even if we saw this, it can not be real since we would have created perpetual motion getting ten times as much energy out as we put in.

 

It is easy to fall for the magic trick, if we use only one moving and one stationary since it is always a wash. But when we have multiple stationary and one moving reference the conservation of energy violation becomes easier to see. From the point of view of any of the stationary references, they will all see only doubled mass in the moving reference plus nine zero relativistic mass gainers. It adds up right, such that they are not the same as the moving reference.

 

Where the trick stems from is only looking at space-time, when SR also have an equation for mass. The space-time affect can create this impression between relative references, since it is not energy obvious. But once you add relativistic mass then conservation of energy has to apply. The mass allows one the see the rabbit in the hat from a better angle. It was a good trick that lasted many generations. I am sorry if I spoiled the fun.

[asprung]

If he were flat he should be dead. If he is not we must conclude that he is as he is in his time frame and only appears different in others.

[iNow]

If he is not we must conclude that he is as he is in his time frame and only appears different in others.

You're getting closer, but it is more than just an appearance. He really is different according to the other reference frames. It's not an illusion.

[swansont]

pioneer, I'm not sure I see your point. Energy is not an invariant when you transform between reference frames, even in a Galilean transform.

[pioneer]

Reference is not relative, but absolute, if we include mass-energy. For example, we have three rockets that start at a zero reference such as the earth. To get them all moving at relativistic velocity, we need to add energy or else we will not be able to get them off the ground to gain relativistic mass. One the misleading assumptions that is often made is starting with relativistic velocity as though it got there without energy. This factors out the energy so the relative velocity assumption appears consist.

 

After all three rockets reach terminal velocity one ends up with 1.1M, the second at 1.5M and the third with 2M. Due to the conservation of energy the last rocket required the most energy input, to double mass. If there was a way for each rocket to determine their own mass-energy through direct measurement, each could back calculate their velocity and know exactly which space-time reference they are in based on a absolute energy scale, relative to the zero reference on earth.

 

If we just use distance and time, then this become ambiguous since each will see their reference appearing to act just like any other. Using only 2 out 3 SR parameters creates an illusion of relative reference that may look like the magician is levitating on the stage. To see that it is a trick we need to include mass to shows the guide wires.

 

Here is one of my older analogies, called the relative reference workout. We go to a track where one person is running around the track. The second person places a chair in the middle of the track and using relative reference pretends he is moving while the runner is stationary. Based on just relative reference one is able to burn calories doing nothing. If we add mass-energy to help sort out the references, since we can monitor the calories burnt by each person, one would have to conclude, that even though the person in the chair thinks he is moving based on relative reference, he is the stationary reference due to the lower calorie output.

 

Relative reference may have an apparent reality of its own. This may make it hard to see who is moving. But once we add mass-energy then the scale becomes absolute. This creates a challenge, sorting out relative reference, to make it absolute, especially when this has going on so long.

[swansont]

Reference is not relative, but absolute, if we include mass-energy. For example, we have three rockets that start at a zero reference such as the earth. To get them all moving at relativistic velocity, we need to add energy or else we will not be able to get them off the ground to gain relativistic mass. One the misleading assumptions that is often made is starting with relativistic velocity as though it got there without energy. This factors out the energy so the relative velocity assumption appears consist.

 

After all three rockets reach terminal velocity one ends up with 1.1M, the second at 1.5M and the third with 2M. Due to the conservation of energy the last rocket required the most energy input, to double mass. If there was a way for each rocket to determine their own mass-energy through direct measurement, each could back calculate their velocity and know exactly which space-time reference they are in based on a absolute energy scale, relative to the zero reference on earth.

 

The zero reference of the earth is artificial — there is no preferred reference frame. And each rocket payload determines their mass to be unchanged, since they are at rest with respect to themselves. That mass — the rest mass — is an invariant in different frames.

 

If we just use distance and time, then this become ambiguous since each will see their reference appearing to act just like any other. Using only 2 out 3 SR parameters creates an illusion of relative reference that may look like the magician is levitating on the stage. To see that it is a trick we need to include mass to shows the guide wires.

 

Here is one of my older analogies, called the relative reference workout. We go to a track where one person is running around the track. The second person places a chair in the middle of the track and using relative reference pretends he is moving while the runner is stationary. Based on just relative reference one is able to burn calories doing nothing. If we add mass-energy to help sort out the references, since we can monitor the calories burnt by each person, one would have to conclude, that even though the person in the chair thinks he is moving based on relative reference, he is the stationary reference due to the lower calorie output.

 

No, since energy isn't an invariant under the coordinate transformation. It's not a valid way of analyzing the situation.

[asprung]

No one has explaned how he can really become flat and live. Does he die in certain refrence planes and live in others ? He only exsts "now" but the answers would suggest he exsits in several diffrent states "now".

[Klaynos]

In his own frame he's not flat, so it's fine.

[asprung]

So how can the other frames be other than illusions.

[swansont]

In the view from other frames, that "flatness" is the normal state for beings traveling at that speed, just like a longer decay time is normal for radioactive particles that are not at rest.

[thedarkshade]

So how can the other frames be other than illusions.

A rough analogy would be this: Suppose that you and a friend of yours are looking at a tree. You are 100m away from the tree while your friend is 20m away. From his view the tree looks higher than from your view, but that's only because he is closer to the tree.

 

The same stand with different reference frames. Different reference frames give different conclusions, not because one is right and the other wrong, but simple because it is being analyzed by different frames. And observers in different reference frames do not contradict each other. Each one's conclusion is correct by their reference frame.