Comments
HunkyMump OP t1_jadba6p wrote
Great answer, thanks for your time. So even though due to expansion of space-time some galaxies will moving away from us at effectively the speed of light, they won’t be “frozen in time” from our perspective because that increase in distance doesn’t equate to an increase in velocity?
rckrusekontrol t1_jadfwek wrote
Well, in a manner of speaking, they might appear frozen in time- we can only see light at that distance, but let’s say we could see our friend Harry.
Since the light from Harry has to cross an increasingly large distance to reach us, he will appear to move slower and slower. It’s taking longer for light to reach us, hence longer for us to see change. Instead he just gets redder and redder, and kind of fades out.
This applies for space time dilation in other areas, ie, Black holes. If you watched Harry head into a black hole, you’d never see him suck in. Since gravitational dilation is rapidly increasing, Harry will slow to a freeze and red shift out. He is already gone but his image/light is taking longer and longer to reach you, until it can’t reach you at all.
Edit; I’ll add that due to the sheer magnitude of time on this scale, everything we observe seems pretty much “frozen in time”. It just takes too long anything big enough to observe to happen , we only get a snap shot. We get lucky and find this or that happening to a distant Galaxy, but we probably won’t be around long enough to see any process play out.
Arylus54773 t1_jad771k wrote
I am not an expert. But I think it is mostly just the degree of red shift when moving away from us. This is why we know that.
KilgoreTroutPfc t1_jad7w1a wrote
The eject is, they have to account for it when calculating long distances.
DolphinWings25 t1_jadea8z wrote
Years may pass with each day we move further from each other because of the enormity of space between us becoming greater and great with every moment of the universes expansion.
towkneeman777 t1_jadhqgx wrote
Does where your standing in the universe affect any of this? If so then how?
failurebeatssuccess t1_jadmokq wrote
No. Expansion is uniform everywhere. There is no centre of the universe, nor an edge.
towkneeman777 t1_jado6c0 wrote
Yes but how to observe the uniformity of the universe don't one have to observing it from somewhere other than said universe ? Just a thought
failurebeatssuccess t1_jae6l0n wrote
Well it looks pretty uniform from what we can see (and we can see a lot of it - the observable universe is huge). There is no good reason to assume there is anything particularly atypical about 'our bit' of the universe and the unobservable universe would be any different).
dittybopper_05H t1_jaea73y wrote
All I know is that I wanted to be very distant when my wife was fully dilated.
towkneeman777 t1_jaeajk8 wrote
I guess I'm seeing myself outside our known or perceived universe and seeing it as like my hand covering the moon. Seeing it all in a glance.. it's all one time and space as I see it... It's about how it's perceived to the observer..
SpartanJack17 t1_jaes2dz wrote
Hello u/HunkyMump, your submission "How does time dilation affect our observations of very distant objects, considering the expansion of the fabric of the universe is causing them to become more and more distant?" has been removed from r/space because:
- Such questions should be asked in the "All space questions" thread stickied at the top of the sub.
Please read the rules in the sidebar and check r/space for duplicate submissions before posting. If you have any questions about this removal please message the r/space moderators. Thank you.
rckrusekontrol t1_jad91sz wrote
You might not mean time dilation- since space is expanding it will not change the speed of objects. Like stretching a balloon, two dots will grow apart, but that doesn’t mean they are traveling relative to each other.
Light doesn’t experience time. But what does the expansion mean for observing distant galaxies? I do know that there are some galaxies that we will never be able to see. The expansion of space will happen faster than their light can traverse that distance.
Other galaxies will red shift until they aren’t detectable any more- light may still be reaching us but that frequency of the light as it travels towards us will slow. This is sort of like being in a wave pool and walking backwards. The time between waves grows greater the further away you get from the source.
When we calculate the age of galaxies, we have to consider expansion, and the degree of red shift helps us figure it out. Light that has been traveling since right after the Big Bang may have only been traveling for 13 billion years… But it will have travelled many many more light years in that time.