/sci/ - Science & Math

Say I'm 20 and I have a twin at proxima centauri who is also 20. If I start travelling towards them at high speed, my line of simultaneity is slanted up, so that for me, they're actually a lot older now, right -- say 3 years older.

If instead I had started travelling away at high speed, for me they would have become 3 years younger.

So, in my frame, whilst I was accelerating, my twin was going backwards in time, getting younger. This is weird and goes against the second law of thermodynamics. Is this a problem?

Also, for places much further away than proxima centauri, billions of light years, they would have been shifted by a huge degree into the future or past. In fact, some places are now before the Big Bang. Is this a problem?

We usually assume that people are conscious at the same time as us, right? For example... when we have a conversation with somebody, we imagine that we're directly interacting with somebody's consciousness, and they are conscious at that very moment. This is almost too obvious to be worthy of comment.

But doesn't special relativity demonstrate that this assumption of synchrony is baseless? Say that it's true, and that your friend, in the same room as you, is conscious at the same time as you. But then you get in a rocket and blast off for a near-lightspeed return trip. For you, when you return, one year (say) of time, and one year of conscious experience, has elapsed. But for your friend, five years of real time has passed. For them, the elapsing of one year of time, and one year of conscious experience, occurred four whole years ago. So if you were initially "synched", your friend's conscious experience is now four years in the past, and when you interact with them, they won't experience that for another four years.

There's therefore no basis at all for assuming synchronicity of conscious experience, and it leads to outright contradictions. All of the people you meet... they aren't consciously aware at that point in time.