Weirdness

D

Deleted member 473

Suppose Relativity were wrong. We would see some really strange things.

Imagine a far away crossroad with a car coming towards you and a car crossing the other way, and suppose the two cars collide.

The light from the car coming towards you would be travelling faster towards you, at speed c + the speed of the car, but that from the other car would be travelling towards you at roughly c.

Result? You would see the car travelling towards you crash into nothing and get smashed, then a short while later you would see the crossing car arrive at the junction and crash.

I find that even weirder than Relativity.
 
This is Special Relativity. Special Relativity is about assuming the speed of light is constant and working out what the consequences would be if that were the case. We can equally well assume some other law and have any weirdness you like.
 
This is Special Relativity. Special Relativity is about assuming the speed of light is constant and working out what the consequences would be if that were the case. We can equally well assume some other law and have any weirdness you like.

No, incorrect! This is without special relativity, where light obeys the additive laws of velocity. In special relativity, you would see the cars collide simultaneously.
 
So it's not actually the Hummy Arms that is the "watering hole of pedantry", but a specific place therein. Seems a shame to limit the scope to one tiny corner of the bar.
 
So it's not actually the Hummy Arms that is the "watering hole of pedantry", but a specific place therein. Seems a shame to limit the scope to one tiny corner of the bar.
I claim the stool in the corner! :)
 
So it's not actually the Hummy Arms that is the "watering hole of pedantry", but a specific place therein. Seems a shame to limit the scope to one tiny corner of the bar.


I assert the right to be pedantic everywhere, just like Black Hole! :frantic:
 
FFS! This isn't "Assume v Presume, the watering hole of pedantry". You know damn well I meant this is a discussion about Special Relativity.

Come on, admit you were wrong!

The point was that in the world that everyone believes is normal and well behaved, the one that seems intuitive and without the strange consequences of Relativity, the Newtonian world, where light behaves like everything else and a fast object sending out light particles will change their speed, there are some pretty weird and unintuitive consequences.

Yes, you could construct other "theories" with even weirder consequences, but this was a discussion about that gold standard of non-relativistic mechanics, the one used to deride the consequences of relativity as unintuitive. There could hardly be anything more unintuitive than the example I gave in the OP. When you observe two objects colliding, you expect to see them actually colliding, not one of them to arrive early at the collision scene and wait around for the other to arrive.
 
I'm having a little trouble with this example.

Would there be a time delay if both cars stopped at the moment of crash or the car moving towards me pushed the crossing car towards me at the same speed?

If I see the crossing car "collide" later than the on-coming car then I would interpret that as the crossing car running into a stationary car.

Would I see the damage to the on-coming car given that the light would be blocked by the crossing car?

Since the light is only transfer medium and I form images out of the light, would I not block out the "glitches" I see and skip to the end result?

Are we sure what we sense is the real world?

Martin
 
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.
 
I'm having a little trouble with this example.

1 Would there be a time delay if both cars stopped at the moment of crash or the car moving towards me pushed the crossing car towards me at the same speed?

2 If I see the crossing car "collide" later than the on-coming car then I would interpret that as the crossing car running into a stationary car.

3 Would I see the damage to the on-coming car given that the light would be blocked by the crossing car?

4 Since the light is only transfer medium and I form images out of the light, would I not block out the "glitches" I see and skip to the end result?

5 Are we sure what we sense is the real world?

Martin

1. No. The approaching car would be seen approaching well before you saw the crash. For a while, the car would vanish from view, and then would appear stationary with the other car collided with it.
2. If the crossing car and oncoming one collide and move towards you, at reduced speed, you will see that after seeing the approaching car approach, but before seeing the crossing car approach. With invisible gaps!
3. The car approaching you would show a dark area where the other car obscured it.
4. It would look really too weird for that to happen.
5. Relativity comes to the rescue and makes things appear rational. You would not see any of the above. Things would happen in sequence i relativity, as the light from both cars would approach you at the same speed.
 
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