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420chan is Getting Overhauled - Changelog/Bug Report/Request Thread (Updated April 10)
Forgive me but... Ignore Report Reply
Tadashi Nakajima - Thu, 26 May 2016 21:42:57 EST ID:VjH9pXwP No.56190
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...I was thinking about Dark Matter. My understanding is that in analyzing the universe, they detect there should be like 3-4 times as much matter as we can account for with stars and such. It just reeks of "luminiferous ether" to me

What if though, there's no invisible matter, but the universe is actually made up of 3-4x more stuff, stuff that is just accelerating away faster than we can see it (faster than the speed of light?). Or is that what is meant by dark matter?
Chushiro Hayashi - Fri, 27 May 2016 06:42:38 EST ID:3t/weoS/ No.56192 Ignore Report Reply
If I remember my astrophysics correctly, dark matter is supposed to be "everywhere". I.e. by taking the observable universe into account scientists can calculate the amount of mass in the entire universe, even outside our light-cone. Much like assuming an entire picture is filled with trees if the small part of it that you saw has trees in it. Not sure what's the rationale behind the idea that the universe is uniform but there you go. So the theory goes that all galaxies are embedded in areas of dark matter.

A very recent hypothesis has an interesting explanation to dark matter. It claims that the stuff is not some exotic, invisible particles, but rather small black holes existing between galaxies. Small enough to not cause any relativistic fuckery like gravitational lensing, so by all intents and purposes this mass is entirely invisible to us.
Roger Penrose - Fri, 27 May 2016 11:23:44 EST ID:y/fkgY/C No.56194 Ignore Report Reply
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The luminiferous aether was disproven by Mechelson and Morley in 1887. It was also necessarily massless. The gravitational effect of dark matter is used to explain the greater than expected speeds of stars in the outer rims of galaxies. There shouldn't be nearly enough ordinary matter in galaxies to account for such high rotation rates. And contrary to what >>56192 said, dark matter does cause gravitational lensing. Pic related is actually a map of the distribution of dark matter based on gravitational lensing observations. Dark matter is almost certainly composed of an unknown subatomic particle (or several).
Roger Penrose - Fri, 27 May 2016 11:25:00 EST ID:y/fkgY/C No.56195 Ignore Report Reply
Chushiro Hayashi - Fri, 27 May 2016 15:35:44 EST ID:3t/weoS/ No.56196 Ignore Report Reply

You don't say?

The plot thickens.
Thomas Henderson - Fri, 27 May 2016 18:22:29 EST ID:xbVB8ilz No.56197 Ignore Report Reply
According to our understanding, gravity waves move at the speed of light.
That means if something is outside the electromagneticly observable universe, it is also too far away for gravity to work.

Dark matter is also mapped on relatively localised levels as the map >>56194 illustrates. Dark matter really just makes galaxies and galaxy clusters more massive. On the scale beyond superclusters of galaxies, gravity stops being the architect and dark energy takes over, which is completely different (maybe).

There should be a cosmic background noise of gravitational waves from the big bang, but what implication that has on the universe, I don't have the math skills to find out..
But maybe, and I could be very wrong, since that was the pretty much the first thing that happened when the universe was created, the CGB could hold some clues over how much mass the entirety of the universe contained before things moved too far away to directly interact, and that could have real direct consequences.
But I have no clue what those would be, I don't know if they would cause space to contract or expand, or change the flow of time, or how the universe would change depending on your location within a universe sized gravity wave
Thomas Henderson - Wed, 01 Jun 2016 18:13:24 EST ID:aZptiHhB No.56203 Ignore Report Reply
>What if though, there's no invisible matter, but the universe is actually made up of 3-4x more stuff, stuff that is just accelerating away faster than we can see it

Firstly dark matter can't just be normal matter. If you analyse the patterns in the cosmic microwave background you find points are correlated which was predicted in cosmology to be from accoustic physics in the very early universe. The details of that correlation tells you how much normal mass there was and how much total mass there is, the two aren't the same. Similarly the abundances of light elements made in the early universe tell us dark matter is not normal matter. The caveat is that the underlying cosmology could be wrong but replacing standard cosmology and repeating all of its successes is no easy feat.

Secondly "accelerating away" doesn't help you. This stuff needs to form halos around galaxies to explain their rotation, it can't do that if its flying away. And why would it all be flying away from us, the observer isn't special. Accelerating away doesn't hide matter. Moving at high speed could but again, then it doesn't work.

Dark matter is very different from the aether for one key reason, cold dark matter has observational successes. CDM predicted those patterns in the CMB before they were observed. CDM predicted how those patterns in the early universe would affect he clustering of galaxies to give the amplitude of the baryon accoustic peak which was not yet observed. It naturally predicts the observations in colliding clusters. Plenty of cosmologists don't like it but no other model to date comes anywhere close in terms of fitting the data available, much less making predictions like CDM does.
John Wheeler - Thu, 14 Jul 2016 13:55:04 EST ID:5pY70gXu No.56275 Ignore Report Reply
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I've been researching possible aether theories that could fall into accord with the current standard model, and well im not sure but this link has some very interesting ideas.
Cecelia Payne-Gaposchkin - Mon, 18 Jul 2016 03:46:58 EST ID:aZptiHhB No.56278 Ignore Report Reply
An aether is completely incompatible with the standard model because they are based in relativity.
Mike Brown - Thu, 21 Jul 2016 09:41:29 EST ID:f/Tl+D5o No.56283 Ignore Report Reply
According to the standard Big Bang model, the universe was born during a period of inflation that began about 13.7 billion years ago. Like a rapidly expanding balloon, it swelled from a size smaller than an electron to nearly its current size within a tiny fraction of a second.

Smaller than an electron.. das it mane from outside of our universe
Johannes Kepler - Sun, 14 Aug 2016 01:01:10 EST ID:XEWmPjnl No.56311 Ignore Report Reply
what if the discrepancy between the expected and actual amounts of matter in the universe is explained by highly advanced sentient beings entering our universe from a separate universe and bringing matter with them (bringing a planet or a ship or building their own custom galaxies or something) ?
Paul Goldsmith - Thu, 18 Aug 2016 00:41:20 EST ID:rszf0FN0 No.56316 Ignore Report Reply
But the actual value is less than the expected value, not more.
Fred Hoyle - Mon, 22 Aug 2016 14:10:47 EST ID:qyc9lsem No.56324 Ignore Report Reply
There's no dark matter. It's just the opposite reaction to the universal constant.

Alan Guth - Mon, 22 Aug 2016 18:20:11 EST ID:rszf0FN0 No.56325 Ignore Report Reply
No, according to LCDM dark energy *is* the cosmological constant. Also if dark matter/energy comprise 97% of the universe, how could 3% of the universe generate an opposite reaction almost two orders of magnitude greater (and also where is the room for ordinary matter in this model?)

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