Questions about Time, Distance, and Relativity

[Mudhammam]

Only the photon experience no passage of time. From the photons perspective, it has traveled 0 distance at 0 velocity for 0 time. To any other non-speed-of-light observer, the photon travels a non-zero distance at velocity c for a non-zero time. This sounds very wierd because traveling at the maximum speed limit of the universe is like doing math with infinities (and techically you are). It can be done, but it's really hard to have any intuitive sense about what is going on.

I still have problems conceptualizing relativity's predictions. However, you can't argue with results.

Yeah, it's quite confusing... Greene writes, "Einstein proclaimed that all objects in the universe are always traveling through spacetime at one fixed speed--that of light... If an object does move through space, however, this means that some of the previous motion through time must be diverted... We now see that time slows down when an object moves relative to us because this diverts some its motion through time into motion through space. The speed of an object through space is thus merely a reflection of how much its motion through time is diverted... the maximum speed through space occurs if all of an object's motion through time is diverted to motion through space. This occurs when all of its previous light-speed motion through time is diverted to light-speed motion through space."

Can you elucidate that?

Yes, the same is true of distance. A common special relativity problem ask's what is the distance between Earth and alpha centauri if you were traveling at 0.9c. The answer is not ~4 light years but ~1.8 light years. This is why you shouldn't think of time and space being two different things. They are interdependent and should be considered as one thing, spacetime.

Ah, that makes perfect sense (duh!).

Not necessarily. You can still have events that no matter what reference frame you look at, the order of the two events would not change.

Does it falsify "objectivity" in regards to the age of the Universe, as that seems to only be true per our level of description, given our state of motion, but not necessarily from a person, say, hypothetically standing on the edge of a black hole's event horizon?

No.

How so? I'm still a bit confused here, particularly on the last point... I'm sure this is a very amateurish question, but if time is not absolute as once conceived, how can an absolute age of the Universe be given? Because the speed of light is absolute? But wouldn't that be... zero? As a hypothetical aside, could spacetime ever be warped to such a degree that it "turns in on itself" and inverts causality?