Weirdness

MikeSh said:
Well I subscribe to light acting like a wave. So like sound it always travels the same speed (for consistent temp, pressure, medium, etc.) regardless of the speed of the emitter. I can't be doing with split crashes.
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Sound travels in a physical medium though. Light doesn't. If it were sound, we would be able to measure the speeds of observer and cars relative to the medium, and calculate accordingly. You can't do that with light, which also behaves as photons travelling at vast speed. It was natural in intuitive mechanics to assume that light would obey the additive laws of velocity. If that is not true, you end up with the weirdness of Relativity instead! Ie, the real world!
 
The basic premis is in error. I accept one can postulate that light could travel at c plus the speed of the emitter, but Special Relativity was never about that - it was about whether every observer perceives the speed of light to be constant or whether the speed observed is c plus the speed of the observer (ie the speed of light is constant with respect to the ether). Paradoxes such as the appearance of a collision do not occur either in Special Relativity or in the Ether theory.

So the idea that light travels at c + v is an alternative postulate which as far as I know has never been seriously considered. As it leads to such rediculous consequences, I suspect it never will be.
 
Black Hole said:
So the idea that light travels at c + v is an alternative postulate which as far as I know has never been seriously considered. As it leads to such rediculous consequences, I suspect it never will be.
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Which I believe to be the point being made by Mike in the first post. Well that seems to have rounded that one off nicely, unless someone knows differently.
 
Black Hole said:
Ether theory.
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Fail! :D



Dimethyl-ether-2D-flat.png
 
Mike0001 said:
Sound travels in a physical medium though. Light doesn't. If it were sound, we would be able to measure the speeds of observer and cars relative to the medium, and calculate accordingly. You can't do that with light, which also behaves as photons travelling at vast speed.
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Well, yes and no.
Light does travel through physical media and is affected by them - prisms, lenses. So we can measure the relative speeds of the participants.
Light can also travel in a 'vacuum', through space, but given that it is beginning to look like that space is actually full of 'dark-matter' I'm beginning to wonder if light (any e-m radiation) does in fact need a physical medium. We just can't see it ... yet :)
 
Black Hole said:
The basic premis is in error. I accept one can postulate that light could travel at c plus the speed of the emitter, but Special Relativity was never about that - it was about whether every observer perceives the speed of light to be constant or whether the speed observed is c plus the speed of the observer (ie the speed of light is constant with respect to the ether). Paradoxes such as the appearance of a collision do not occur either in Special Relativity or in the Ether theory.

So the idea that light travels at c + v is an alternative postulate which as far as I know has never been seriously considered. As it leads to such rediculous consequences, I suspect it never will be.
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OK, so I am sat stationary in the aether watching this car approach me at twice the speed of light relative to the aether, and I see it crash into another car crossing its path. But what do I actually see? I see the car at its collision point, and then travelling backwards, and repairing itself as it recedes towards infinity.

You claim that isn't weird? :disagree:

It's even weirder if it accelerates and decelerates across the speed of light. Far weirder.
 
Weirdness #2.

I sit at the centre of a very large wheel with spokes stretching out to infinity. I see it exactly as it is, except the further I look out, the further in the past I see, because of the finite speed of light.

OK, but what if the wheel is rotating? Because of the delay in seeing each spoke the further out I look, the spokes look like spiral arms, curving back in the opposite direction to the rotation.

But if I myself rotate, and the wheel remains stationary, I see straight spokes.
 
Weirdness #3:

Take two polarizing filters and pass light through them consecutively. As you rotate the second filter, so its direction of polarization is perpendicular to the first, the transmitted light goes to zero. This is common knowledge.

Now take a third filter and place it at 45 degrees to the other two, and between them. Light now gets through all three filters:

Light---> Filter at 0 degrees ---> Filter at 45 degrees ---> Filter at 90 degrees

The weirdness is that the outer filters should block all light, but they don't.
 
Mike0001 said:
I see the car at its collision point, and then travelling backwards, and repairing itself as it recedes towards infinity.
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No you wouldn't, not in Newtonian physics and impossible in Special Relativity?

Weirdness 2: Yes, if you could make a wheel large enough. In SR there would be a maximum size of wheel that can be solid.

Weirdness 3: You've strayed into Quantum Physics, and at the moment there is no theory which can account for Quantum Physics and Relativity at the same time.
 
Trev said:
Why would it get long? Approaching c, things get shorter.
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In Special Relativity, when you calculate lengths, yes, things get shorter, but as observed, they look normal length, even at speeds approaching c.
 
Black Hole said:
:disagree:
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It's true. You do not observe the actual contraction. You have to calculate back to determine that a contraction actually happened, but what you see is different.

If a spherical star approaches and passes you at relativistic speed, you see it as spherical. Of course, to appear spherical, you know it must have been contracted, since otherwise it would have appeared elongated.

http://www.spacetimetravel.org/fussball/fussball.html

If a rod travelling in the direction of its length flies past you, it appears elongated as it approaches and contracted as it moves away. As it flies past, perpendicular to your line of sight, it appears to have exactly the correct length!
 
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