[ 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: 203 KB, 800x730, NASA-HS201427a-HubbleUltraDeepField2014-20140603.jpg [View same] [iqdb] [saucenao] [google]
8713572 No.8713572 [Reply] [Original]

Olber's Paradox: if the universe is infinitely large and has existed for an infinite period of time, then everywhere you look in the night sky should end in a star.
>look in sky
>there's dark spots
>"well I guess the universe hasn't existed forever, then"

>look again with a really long exposure time
>the dark spots are no longer dark

Why are we sure the universe hasn't existed indefinitely again?

>> No.8713575

the universe isn't infinitely large nor infinitely old

>> No.8713589

>>8713575
Do you have any evidence that supports that assertion?

I might claim that the Ultra Deep Field photo supports the hypothesis that the universe is infinitely old and therefore infinitely large, because if you wait long enough you'll expose an image of something very far away. If you wait longer you'll see something even farther away.

>> No.8713593

>>8713589
I do. You'll surely arrive at the trivial evidence by thinking it about yourself. Instead of asking stupid questions.

>> No.8713615

>>8713589
If you accept the Big Bang model then surely you accept >>8713575 ?

>> No.8713634

>>8713572

Here's a nice paper about different cosmological horizons, which goes significantly further than a lot of standard explanations:

https://arxiv.org/abs/astro-ph/0310808

>> No.8713649

the universe is both infinitely old, it just recycles itself in a big crunch

>> No.8713680

>>8713649
The universe reversing course seems implausible. More likely it expands until it explodes again, everywhere at once.

>> No.8713747
File: 287 KB, 748x1200, 1488325291290.jpg [View same] [iqdb] [saucenao] [google]
8713747

>>8713572
>brainlet attempts though experiment

>> No.8713788

>>8713589
False.

If you were to take an "ultra deep field" shot of a dark spot in Hubble's UDF you would maybe see a few more super redshifted old galaxies and some of the first stars, but other than that you would just be looking at the CMBR, which is in fact what proves that the universe isn't infinitely old or large.

>> No.8713811

>>8713572
Google WMAP images.
Go from there

>> No.8713836

>>8713788
Actually let me modify that last sentence - the CMBR doesn't prove the universe isn't infinitely large, only that it isn't infinitely old. There could be an infinite amount of space and galaxies that you would see with a powerful telescope if it weren't for the fact that the limiting factor in how far you can see is the age of the universe.

And there are galaxies that exist outside our field of view, but we'll never get the chance to see them because they're further away than the universe is old.

>> No.8713841

the universe..heh..what a concept

>> No.8713860
File: 849 KB, 200x200, tumblr_lwkn32ZtAM1qzb8j3.gif [View same] [iqdb] [saucenao] [google]
8713860

>>8713841

>> No.8713867

>>8713747
>actually playing the Danish
What's it like being <2000?

>> No.8713874

>>8713867
Feels pretty bad desu.

>> No.8714189
File: 5 KB, 383x107, surface_area_of_a_sphere.png [View same] [iqdb] [saucenao] [google]
8714189

I don't see how this is a paradox. Photons are emitted from the surface of a star as a spherical emission field and that emission field diminishes by the inverse square law.

At the surface of the star the photons are densely packed as they are emitted but the farther away I am from the star the less dense that spherical emission field will be. Every time I double the radius of a sphere I divide the field density by 4.

>> No.8714204

Come on, this is intro level astrophysics guys.... this board is sad.

The answer is that the universe is expanding, and light from very far away stars becomes dimmer and dimmer, and some will never reach us at all.

>> No.8714218

>>8714204
This proves nothing about the age or size of the universe though. You have to take that extra step and observe that all distant galaxies are accelerating away from us. Then if you trace all the trajectories backwards through time you show that everything was once at a single point in space, and this is what we call the beginning of the universe.

>> No.8714224

>>8714218
I never said it did. I'm just saying the reason the night sky isn't full of starlight is because of the cosmic horizon and redshifting of light that is further away.

>> No.8714244

>>8713572

The proper conclusion to draw is that there are uncountable many stars, but not an infinite number of stars.

The other conclusion to draw is that if the universe's expansion is accelerating, and it is, it is not infinite.

The other conclusion to draw is that if there were infinite time, we would be in heat death right now, and we're not.

>> No.8714250

>>8714224
>I'm just saying the reason the night sky isn't full of starlight is because of the cosmic horizon
There is no obvious observable evidence for this. It takes some additional assumptions and deductions to be able to state a cosmic horizon exists.

>and redshifting of light that is further away.
That was already stated in the OP:
>look again with a really long exposure time
>the dark spots are no longer dark

Don't call the board sad when you have no reading comprehension.

>> No.8714251

>>8714189
Photons don't exist. Light doesn't travel at a speed. Light has a rate of induction as it is a coaxial longitudinal circuit.

>> No.8714350
File: 209 KB, 510x346, i get it.png [View same] [iqdb] [saucenao] [google]
8714350

>>8714251

>> No.8714370

>>8714250
https://en.wikipedia.org/wiki/List_of_cosmological_horizons#Hubble_horizon

>> No.8714448

>>8714370
Yet again you fail to show any reading comprehension.
>It takes some additional assumptions and deductions to be able to state a cosmic horizon exists.
Like for example the speed of light being a constant or the outward expansion of the universe.

Also, the first paragraph of that link shows that the Hubble horizon has no relation to the discussion in this thread:
>Note that this does not mean the particle is unobservable, the light from the past is reaching and will continue to reach the observer for a while.
If the light is still able to reach us, how does this apply to Olber's paradox at all?

>> No.8714475

>>8714448
Now you're just flat out denying science. The universe is expanding. That is observable. The speed of light is constant.

Once objects go beyond the hubble horizon their light can't reach us.

>> No.8714485

>>8714244
as if it can't be infinite AND expand