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Some Observers Perceive the Universe To Be Much Younger Than We Do
StartsWithABang writes: It's been 13.8 billion years since the Big Bang for us, and when we look out at a distant object in the Universe, we're seeing it as it was in the past. Its age — as it appears — is determined only by how long the light took for it to travel from that object to our eyes, but to someone living there, it will also appear that the Universe is 13.8 billion years old. But it is actually possible for an observer living on another planet, star or galaxy to perceive that significantly less time has passed since the Big Bang, so long as they were moving close to the speed of light relative to the CMB. Paradoxically, if they slowed their speed, they'd find that they themselves were very young, but living in a 13.8 billion year-old Universe.
A better way to put it is that when you are travelling nearly the speed of light, if you look behind you at the place you are heading away from time seems to stand still for it; the light from your old hometown is redshifted. But light that's coming in from in front of you (and thus, the perceived rate of time) is way higher. Time seems to be moving a hundred times faster than normal as you look at an oncoming blueshifted star. Then, the star passes you and all of a sudden it slows down... from your point of view.
So from the point of view of the fast moving observer, time is sped up in front of them, and nearly frozen behind. As they travel they pass galaxies that are growing old very fast, but leave behind them a frozen universe, that is changing imperceptibly slowly.
When they stop... they are not 'surprised' that the universe is old. They watched it grow old in front of them. Nor are they surprised that their home, now billions of light years away, has not changed much (it looks 'young') because behind them time seemed to stop. The perceived universe makes sense from the viewpoint of the traveler. Point being that there is no paradox. What happens to the fast moving universe would look really weird from inside (because of the starbow effect), but they would be used to it. You know... assuming they survived the X-Ray energy sleeting through them from impact with intergalactic matter.
"I will trust Google to 'do no evil' until the founders no longer run it." Hello Alphabet.
Unfortunately I'm not at all sure that he actually got it right though because I think he has forgotten about General Relativity. He treats the entire universe as if it were a single object at rest in the CMB frame. However it isn't: it consists of many constituent components all with their own individual rest frames.
As we look further away from us galaxies are travelling closer and closer to the speed of light and so appear "slowed down" by time dilation due to the expansion of space itself which you need general relativity to account for. All that travelling close to the speed of light should do is shift which galaxies are slowed by time dilation and which are in almost the same frame and so not slowed. Hence you would see effectively exactly what we see now but it will be different galaxies which are in view because you are in a different inertial frame.
Hence I am not at all sure that he got it right. Certainly I'd like to hear it from a cosmologist before I believe it since GR is far more complex than SR and it is easy to get stung applying SR to a situation which requires GR and hence my cautiousness about whether he is wrong since I'm not a cosmologist. This would far from the first thing that he has got wrong...but it would be the first truly spectacular failure.