# Relativity and Quantum's multy universes

1. Sep 6, 2008

### mich

The last thread I started consisted of the problems that I had with the implication of length contractions of a moving frame as measured by an observer on a different reference frame, although I had no problems with time dilations. With the help of all of you, I have now come to understand why a lenght contraction is needed as well as a dilation of time.
My original thought was that there could be an experiment which might prove whether or not a contraction could be observed, by simply doing the M&M experiment, having the observer (sensor) on a moving frame.My thought was that Relativity would predict that the observer on the moving frame would disagree with the observer stationary to the experiment concerning the simultaneity of the event when the two light signals arrives at the sensor. I was shown why this couldn't be done because both Relativity and Newtonian mechanics would predict the same outcome,that is, both would see the event as being simultaneous. therefore, proving nothing whatsoever.

My thought continues from here; so what would be the consequence, then, if the experiment was done and, to everyone's amazement (which was the reaction of Michelson), the event was observed as being non-simultaneous by the observer on the moving frame, relative to the experiment?

While it would disagree with Einstein's first postulate, it would not disagree with Relativity as such. For one thing, no form of classical
physics could predict such an outcome. But what about Relativity?

If we assume that the measuring rods within a moving frame, as measured from an observer on a different frame, is contracted not only in the direction of travel, but everywhere within the frame itself, then, it would explain the hypothetical outcome.The whole frame becomes contracted or smaller instead of just in the direction of motion only. The length of the vertical leg, being also contracted, would leave the hypotenuse also to be shorter, being the path of light observered by the observer on the moving frame.
The implication of this hypothetical outcome could be fairly important, since this would imply that certain events, such as a collision between two particles could exist on one frame while a nearmiss would be observed by another different moving frame. Observers on different frames would constitute an observation of, not only different time or length measurements, but also of different realities.

Andre

2. Sep 6, 2008

### Staff: Mentor

I assume by "the event" you mean the arrival of the split light pulses back at the source after having made their round trips along the vertical and horizontal arms of the interferometer.

If the light pulse could arrive at the same point at the same time in one frame, then relativity demands that they arrive at the same time in any frame.

(Michelson was "amazed" because everyone took for granted that there must be an ether.)

3. Sep 6, 2008

### mich

But what if the experiment was done and the outcome would be the observer on the moving frame (sensor) see the local event as being non-simultaneous? What would this imply?

I mearly wrote that "if" such an outcome would exist, scientists would be just as amazed as Michelson was.

Andre

4. Sep 6, 2008

### Staff: Mentor

To make this point sharper, imagine a detector at the meeting point which registers the arrival of the two light pulses and triggers a bomb if and only if the pulses arrive simultaneously (in practice, within a suitably small time window, of course). How can the bomb possibly go off in one reference frame but not in another, in any viable relativity theory?

5. Sep 6, 2008

### mich

I totally agree that this is not what Relativity claims. I simply allowed a Quantum element within the picture. In one frame within the universe, the bomb explodes, while others, it doesn't.

I am actually asking that if the M&M experiment would be performed and such outcome would exist, what would be it's implication?

Andre

6. Sep 6, 2008

### Staff: Mentor

How could we observe such a quantum multiverse situation, when we (the observers) are always in one of the universes and can therefore observe only one of the outcomes? (the bomb going off or not going off)

As far as I know, the "quantum multiverse" is purely an interpretation of quantum theory and experiments, and only one of several possible different interpretations. People argue endlessly about these interpretations because there is no way to choose between them by experiment.

Last edited: Sep 6, 2008
7. Sep 6, 2008

### RandallB

Well you are in another thread but did you take the time to understand M&M. Does not seem so – who or from where did you get the idea M&M was “proving nothing whatsoever” ??
The idea that “Relativity and Newtonian mechanics would predict the same outcome” for M&M is incorrect!!

M&M used Newtonian mechanics i.e. Classical to show that the M&M experiment would clearly show shift in the interference pattern from the two beams of light not coming back to their start “simultaneous” or more correctly stated in a changed phase. What the experiment PROVED was there was something wrong with the Galileo Newton Classical interpretation because there was no shift. You need to read your M&M source or find a better source.

Plus I don’t see how you can convert M&M into some kind MWI issue.

8. Sep 6, 2008

### mich

If one performed the M&M experiment with the light sensor (observer) placed on a moving frame; and if the sensor would detect a shift in the two combined light spectrums,making the event non-simultaneous,then we would have not only a difference in clock rates, and measuring rods, but a difference in events as well, that is, a difference in reality.

Andre

Last edited: Sep 6, 2008
9. Sep 6, 2008

### mich

And that's what I thought as well; but I was given some help to see why it is so.Read carefully now... the M&M experiment is done having the observer on a moving frame.

Newton believed that light was made of particles....redo the M&M experiment having this in mind and you will clearly see that Newton would have predicted the nul result.

I'm just passing time here, Randall, throwing thoughts around to see what happens, that's all....I'm not a scientist of any type whatsoever, so I don't pretend to know what relativity is all about. I'm simply pointing out the parts I'm having problems with.

Andre

10. Sep 6, 2008

### JesseM

This doesn't really make much sense--if they were in different realities, how would they communicate? Would each reality have its own version of both observers, so in reality #1 the first observer's prediction was right and the second's was wrong, and in reality #2 the second observer's prediction was right and the first's was wrong? But in this case none of the observers would know about the different realities, they'd each just think they were in a single universe where one observer was correct and the other was wrong, indicating a preferred frame.

11. Sep 7, 2008

### mich

If I'm not mistaken,Jesse, the Quantum weirdness identifies a version of you in all the different universes, one doing something a bit different than the other. The collapse to one reality might have something to do with conciousness, or even the laws of nature.So in the version of the M&M experient, all of the universes would be somewhat identical for this experiment except if someone scrutinized the experiment, some would notice a small error in the fringes. However, within the version of the bomb,the miscalculation which was done within the frame simply exploded?

Andre

12. Sep 7, 2008

### JesseM

Only in the many-worlds interpretation of QM (which is experimentally indistinguishable from other interpretations of QM that don't involve different universes), and even in the MWI there's no way to communicate with other versions of me.
But you didn't answer my question--in each universe, wouldn't there still be versions of both the observer at rest relative to the apparatus and the observer moving relative to the apparatus, and wouldn't they have to agree on what the fringes looked like, or whether the bomb exploded? If so then from their point of view it would just seem like one frame was wrong and the other was right, it would be irrelevant to them that the other frame was right in a different universe.
I don't understand this sentence--"within the version of the bomb"? The miscalculation exploded?

13. Sep 7, 2008

### mich

No there is always one you in every universe; everytime you change your frame of reference, you change your universe however subtle it may seem....even by changing directions when walking.However, with such low speed the effect would be unoticable.

Let's retake the experiment, since I think I had it backwards.

jtbell wrote that the bomb would be activated only if the signals arrived simultaneously...I think I was explaining it backwards.

Ok; so, on the "rest" frame of the experiment, there ought to be a Kaboom, whereas you, being on a different frame would see the experiment as having failed due to some error, you would be told, if you return to their interial frame. but by returning to their interial frame, you would not be returning to yor old universe but still a different one.

I had such a problem when dealing with Relativity myself, however, the answer lies in the fact that they are already within two separate universes due to their different inertial frames and can return and share the same universe again only when one returns back at rest of the other.While they are on separate frames, they would be like in a quantum uncertain state, such as found in Schrodinger's cat paradox.However, to say they will share the "same" universe after returning on the same reference frame,is not the same as saying that he will return to his old universe...I don't think this would be feasable .And we know what oddities this constitute....the twin paradox. There might be other oddities as well.

In other words while Relativity speaks of different frames of reference, it would be the same as saying different universes.

This is because I think I was taking the experiment backwards.

Andre

Last edited: Sep 7, 2008
14. Sep 7, 2008

### JesseM

OK, but suppose after observing the experiment I then look at my friend in motion relative to me, and he is holding up a sign saying what he saw. If I saw the bomb explode, are you saying I'll see him holding up a sign saying he didn't see it explode? Or are you saying I'll see him holding up a sign saying he did, but then if I change speeds to come to rest relative to him, I'll see his sign change before my eyes?
I just didn't understand the grammar. What is the "version of the bomb", and what does it mean to be within it? Do you mean "within the frame of the bomb" or something? And when you wrote "the miscalculation which was done within the frame simply exploded", the structure of that sentence makes it looks like you're saying the miscalculation itself exploded, which doesn't make sense to me.

15. Sep 7, 2008

### RandallB

But this is the reason you are having problems with relativity. You need to “Read carefully now” when reviewing your source on M&M - - did you?; everyone that does understands that the observer is assumed to be moving in a M&M experiment, but what is unknown is which way is the observer moving. That is why the experiment requires turning and comparing results. You represent that you know M&M, did you read and clearly understand that part? The issue and paradox is why doesn’t the experiment reveal which direction that motion is as M&M expected base on what they know from Newton! I.E. Classical does not predict a nul result – period.
Exactly who said "Newton would have predicted the nul result" for the M&M experiment?

You won’t be able to keep up in a MWI discussion while still having problems with basic SR.
And you always be confused and are not going to catch up with those that understand SR till you understand how the M&M paradox help build SR in the first place.

16. Sep 7, 2008

### Staff: Mentor

Sorry, but your identification of different reference frames with different worlds (in a MWI sense) seems like nothing but idle--and rather incomprehensible--speculation.