Hacker News new | ask | show | jobs
by arithma 3451 days ago
But we do say we see the Sun as it were 8 minutes ago because of distance/c. Are you suggesting that this notion be removed as well, because I agree with you regarding the light cone, but the Sun being 8 minutes away makes too much sense for me to abolish the concept. Is there any philosophical speak about this topic or is it basically resolved?
1 comments

There exists a reference frame in which the distance between the Sun and earth is so compressed by Lorentz contraction that the light leaves the Sun and arrives at the earth in 1 second. In relativistic terms, the photon leaving the Sun and arriving at the earth can be considered to be simultaneous.
> In relativistic terms, the photon leaving the Sun and arriving at the earth can be considered to be simultaneous.

No they cannot, unless you boost to a reference frame that's moving at the speed of light, which is a useless frame. In all other frames, including the ones we are in, the photon left the Sun before arriving to Earth.

> There exists a reference frame

But is that the reference frame that we experience?

Obviously, no.
> In relativistic terms, the photon leaving the Sun and arriving at the earth can be considered to be simultaneous.

You just constructed an argument that can be readily used to argue that all events are simultaneous. That should flip your internal bozo bit and help you see that the argument is not sound.

> You just constructed an argument that can be readily used to argue that all events are simultaneous

No, I haven't. I have studied relativity in University, have you? Lol @bozobit

I will make the statement more rigorous.

"Let event A represent the emission of a photon. Let event B represent the arrival of a photon elsewhere. Event here refers to a unique location in space-time i.e (x,y,z,t). As per special relativity, you can always find a reference frame such that the time separation between A and B can be arbitrarily small. It can't be made exactly zero, but it can be made as close to zero as you wish to."

Use this formula to figure out the reference frame of interest.

https://en.wikipedia.org/wiki/Length_contraction

The speed of light is constant. So decrease/contract the length until the time required = distance/c is one second or less.

If you feel like getting mystical about it, for a hypothetical Photonic Being all events are in fact simultaneous: It is always 'now' and per various mystic schools, that 'timelessness' is the actual meaning of 'Eternal'.