/sci/ - Science & Math

>>12237052
I think that you would not have posted this comment an infinite amount of times, nor would Earth have existed an infinite amount of times either. During the time that matter/energy was in it's very hot dense state, quantum uncertainty would produce small imperfections in the distribution of matter that resulted in it no longer being perfectly homogenous and isotropic, just as we see today. Since these quantum fluctuations are probabilistic, no two big bangs would exactly a like.

As the universe expands, these small imperfections would become more pronounced, eventually leading to the formation of galaxies. Without these early quantum fluctuations the distribution of matter would likely be entirely homogenous and isotropic, meaning no galaxies would ever form.

>>12003741
I was using "angular scale" to refer to the size of the average colored blobs in this picture: the acoustic oscillations. Neither theory nor phenomenology had any idea what this should have been before it got measured.

>The angular scale of what?
acoustic oscillations

>See the paper I attached.
Equations 4 and 5 are equations of state. Where do these come from if not previous experiments? I won't be able discuss it with you further than that. If you say it's not parametrized then I won't have anything to say about it because I'm not familiar enough with the various equations of state to know where they come from. You might be right. If you can understand that whole paper then you know a lot more about it that I do. However, Eqs 4 and 5 look parameterized to me. If you say they're not, I won't have any way to disprove you.

>Also wrong. See my figure.
If it wasn't phenomenological, then wouldn't that mean it was based on a guess regarding the scale of the acoustic fluctuations which were not known before the experiments measured them? You have demonstrated superior subject mastery. Since I can't even understand the vertical axis on the plot you refer me to, I don't think I will be able to continue to offer well-reasoned responses to your highly specific claims.

>You're ranting and raving about the scale but that is not the point I'm making, at all.
The scale of the acoustic fluctuations is what was important for the rate of galaxy formation and similar processes: big picture astronomy/astrophysics stuff. It was YOU who misunderstood ME when you thought I was talking about the power spectrum instead of the acoustic oscillations. I thought the power spectrum was a minor detail determined by these experiments compared to the scale of the acoustic fluctuations in the sky. Why do we give a shit about the power spectrum? I don't know. The scale of the acoustic oscillations governs literally everything in astrophysics.

Is the CMB changing if we keep observing it? What's the timescale on that?

Why do we talk about shit in space that's billions of light years away when chances are they probably don't even exist anymore? Fucking stupid

>>11650635

>hypothesis

We have pretty strong evidence up to the 10^-43 seconds. We know because we have reproduced the result in laboratories, computer simulations and particle accelerators. We also have direct evidence up to 13 and a half billion years ago thanks to the Cosmic Background Radiation.

Note that classical Big Bang theory is obsolete as it has 3 major flaws:

>The Horizon Problem
>The Flatness Problem
>The Magnetic monopole problem

Which lead to the development of the concept cosmic inflation. Also, it doesn't say anything about the origin of the big bang itself. It runs Einstein's equations all the way back until the equations predict a singularity and enters into conflict with quantum mechanics. Is this approach valid? It is better to think of the big bang as a theory of the earlier universe rather than its origin.

Given that the cosmic microwave background radiation is measured with such excruciating precision, how much longer will it be before a rate of change is measurable?

>>8091506

If you keep looking far enough, you reach the CMB. This is a view of the universe from a long time ago, when it was hot and opaque. This happens when I look in any direction so I imagine a big sphere with a radius of 13.whatever light years centered on my head.

If you could somehow see through it, you'd eventually see the very beginning. So, if I expanded my sphere a little bit more, I'd reach the beginning of the universe at the edge of my enormous sphere.

Now imagine someone on a planet 6 billion light years away. Our spheres would overlap, but not be the same, right? But then how can I make sense of the stuff in his sphere that isn't in mine? It would appear to me to be outside (and therefore before?!) the big bang?!

This has been doing my head in for days. Please help, /sci/!

>>4760827

>the big bang
>started from ALL POINTS, forever expanding
>no friction in space, nothing to stop material >movement

there is no "center" to the universe. Every direction we look we see the big bang.

Now start thinking with portals

Need cosmological/space pictures for my screensaver. Thank you /sci/ons of Pythagoras.

>>3425998

just posting some cosmic microwave background radiation

hey sci, Marcus Chown in the never ending days of being dead...claims that there being an infinite number of versions of the planet earth is a corrolary of quantum mechanics and the standard theory....this eems to be based onm the belief that "no serious cosmologist" would dispute the inflationary theory of the universe and that this implies an infinite number of bubble universes.....how ubiquitious is the view that we have an infinite number of bubble universes?

>>2136953
>>2136697
No, whether two points in space can separate from each other FTL is very relevant to your question. I think you may be confusing the kind of redshift caused by relative velocity (i.e Doppler effect) with the kind caused by the expansion of space.

Space, as you know, is expanding. This isn't merely galaxies moving away from each other, but spacetime itself expanding, and the difference is crucial. If you emit a photon and have it travel over intergalactical distances, then the stretching of space will likewise result in a stretching of the photon. You could imagine a wave representation of the photon stretching out, so that it increases in wavelength. Redshift!

It is the same stretching of space that explains why light from the edge of the (observable) universe is still traveling towards us today. I like the analogy with the raisins in the bun. You have a bun made of dough, which is expanding (because you're baking buns nigger). The dough is spacetime. Inside of the bun are raisins, which will represent galaxies. Imagine that a raisin emits a photon in the direction of another raisin while the bun is expanding. Locally, the photon is moving away from its mother raisin. But all the while, the distance between the two raisins (galaxies) is growing, because the dough (spacetime) is expanding. So the photon will indeed move towards that other raisin, but only if the velocity of the photon can overcome the increase of distance between the two raisins will it ever reach its destination! If the distance is growing FTL, which it might, then the photon will never arrive. This is why the universe is larger than the observable universe.

And by the way, the light we see today is NOT from when the universe was just a little speck. It comes from the recombination epoch at the earliest, because before then, the universe was not transparent to photons. Pic related.

>>1559183
> big bang
> impossible to detect

Don't mind me. I'm just the Big Bang still actually there, still happening, and still visible to be directly seen.
Pic related, it's the Big Bang happening everywhere 13.75 billion years ago and still going strong.

Is the universe really expanding, or is it only the region we are in that is expanding?