[ 3 / biz / cgl / ck / diy / fa / ic / jp / lit / sci / vr / vt ] [ index / top / reports ] [ become a patron ] [ status ]
2023-11: Warosu is now out of extended maintenance.

/sci/ - Science & Math


View post   

File: 56 KB, 621x702, brainlet.png [View same] [iqdb] [saucenao] [google]
10495434 No.10495434 [Reply] [Original]

If light is travelling faster than the universe is expanding, what happens to light that overtakes the edge of the universe?

>> No.10495437

>>10495434
>If light is travelling faster than the universe is expanding
It's not

>> No.10495438
File: 42 KB, 632x300, gthfd.jpg [View same] [iqdb] [saucenao] [google]
10495438

>how can something be expanding and not have an edge
pic related

>> No.10495440
File: 5 KB, 211x239, you.jpg [View same] [iqdb] [saucenao] [google]
10495440

>>10495437
The H0liCOW estimate puts the Hubble constant at about 71.9 kilometers (44.7 miles) per second per megaparsec (one megaparsec equals about 3.3 million light-years). In 2015, another team, using observations of the cosmic microwave background, determined the rate was 67.8 kilometers per second for megaparsec.27 Jan 2017

visible light is about 1.0003, so the speed of light in air is about 299,700 km/s ...
>>10495438
I am aware of this model but if you travel in the same direction you would exceed the bounds of the universe eventually since light is so much faster and doesn't decay, correct?

>> No.10495441

>>10495438
>>10495440
or are you saying light would literally loop back round somehow? it has to be one or the other

>> No.10495442

>>10495440
you're wrong for the same reason you can fly around the earth indefinitely

>> No.10495446
File: 52 KB, 903x960, literallyme.jpg [View same] [iqdb] [saucenao] [google]
10495446

>>10495442
so it does loop?

>> No.10495450

>>10495442
>>10495438
don't both of these models fail if the light is given off from the initial big bang? it would travel directly outwards perpendicular to the surface of the balloon or bubble

>> No.10495451

>>10495440
you are a massive brainlet

>> No.10495457
File: 566 KB, 934x768, tearsofjoy.png [View same] [iqdb] [saucenao] [google]
10495457

>>10495451
I googled it when nobody gave a satisfying answer and the answer is nobody has even the slightest idea, it's a very valid question so I am smarter than you in this case

>> No.10495463
File: 8 KB, 225x225, download (1).jpg [View same] [iqdb] [saucenao] [google]
10495463

>>10495446
looping could be a solution. Pretty weird experiential implications if it was. pic related

>> No.10495559

>>10495434
I think you know why the observable universe is approximately 46.5, not 13.8. so move on.
The statement is not related to whether space is expanding or not. you can replace this statement within current spacetime when wording "light" is changed to "sufficiently fast tachyon".
just like in the ground the earth looks flat, we look at 4-dimentional spacetime and it literally looks flat. 1.00±0.02, when 1 is flat. if Omega is bigger than 1, it will be hypersphere-y
so in the hypersphere-y spacetime, we can naturally model of the space where 3d space is surface. (looks contradictory but think about 4d)
In this case, the light can go all the way round and can go back to observable universe, even earth. just like ship on earth can back to where it started.

>>10495463
this guy corrects

>> No.10495595

>>10495438
Now imagine the curface of the balloon to be 3d.

When will people realize space is unbounded.

>> No.10495601

>>10495559
>you can replace this statement within current spacetime when wording "light" is changed to "sufficiently fast tachyon"
This bit is nonsense

>In this case, the light can go all the way round and can go back to observable universe, even earth. just like ship on earth can back to where it started.
This bit is actually correct (for Omega > 1)

>> No.10495624

When we look at distant galaxies we see they're all receding, with most distant galaxies receding faster. This is due to the expansion of space in the universe.

So more distant galaxies recede faster, what about really distant galaxies? Galaxies further than the "Hubble radius" are moving away from us faster than light (this is allowed due to the geometric spacetimey nature of expansion, it doesn't break any laws). If the expansion were to slow down then the Hubble radius would grow and galaxies that used to be superluminal are now subluminal, so their light will eventually reach us. So even if you're receding superluminally now in the future we might still have a chance of seeing their light.

>> No.10495986

>>10495434
It turns into a vampire.

>> No.10496032
File: 11 KB, 411x387, 1454775640644.png [View same] [iqdb] [saucenao] [google]
10496032

if universal expansion deccelerated, then does that mean one day the night sky could suddenly light up?