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#2701 DShomshak

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Posted 02 June 2017 - 05:15 PM

In the June issue of Scientific American, theoretical physicist Yasunori Nomura discusses an idea he's had to resolve one of the big problems with the Cosmological Inflation theory. I hope that I understand him well enough to adequately summarize his argument.

 

The starting point is that a fraction of a second after the Big Bang singularity, the nascent universe experiences a moment of incredibly fast expansion that flattens out space-time, accounting for the near-perfect flatness of space seen today. The problem is that the phase change from the inflation phase to normal expansion can't be perfect: Parts of space keep inflating, almost instantly becoming bigger than the "normal" universe. Bits of space-time keep bubbling out of the perpetual inflation, creating new universes in a "multiverse."

 

Unfortunately, it follows that in such an endlessly multiplying Multiverse, anything imaginable -- no matter how improbable it may seem -- not only happens, it happens an infinite number of times. This makes the whole notions of probability and prediction meaningless.

 

Nomura, however, tries to link inflation with another theory that seems to predict everything: the Many Worlds interpretation of quantum mechanics. In this interpretation, every possible outcome of a quantum mechanical event actually happens, in an endlessly splitting "tree" of diverging universes. The math works; it's just hard to imagine the universe actually functioning this way.

 

Nomura also draws on a similarity he sees between the event horizon of a black hole and the "event horizon" of the observable universe. Just as no matter or energy can pass from the interior of a black hole to the outside (but information possibly can), nothing beyond a particular distance can ever affect us because it's receding faster than the speed of light.

 

Nomura thinks the bubbling multiple universes of inflation theory do not exist in a super-energetic but otherwise ordinary, larger space-time. Rather, he thinks they exist in the probability "space" of Many Worlds quantum mechanics. Even if every possible outcome in some sense occurs, they still have different mathematical probabilities. (How, I don't know. I just take mathematicians' word for it.)

 

Now, I tend to roll my eyes when another theoretical physicist says his Great Idea will Revolutionize Everything if the math pans out. Nomura, however, says his theory has produced a testable prediction: The universe should include observable areas of negatively curved space. (He doesn't spell out how one detects negatively curved space, but I presume the effect would resemble that of a negative gravitational field. Perhaps "gravitational" lensing, but the lens is concave instead of convex?) If the "conventional" inflation theory is correct and all the multiple universes exist in a wider space, any instances of negative special curvature can still exist, but the curvature should be much less -- so much less that Nomura doubts they could be detected at all.

 

So, that's one more thing for the deep-space astronomers to look for. Kudos to Nomura for producing a theory that can be tested.

 

Also, unrelated: I just heard that LIGO detected another pulse of gravitational waves.

 

Dean Shomshak


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#2702 dmjalund

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Posted 03 June 2017 - 12:59 AM

I always thought inflation was caused by the collapse of a false vaccuum


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#2703 DShomshak

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Posted 03 June 2017 - 05:12 PM

That's one way I've heard it described. Some kind of phase change in space-time, anyway, but as a layman my understanding is only at the hand-waving, "And then a miracle happens" level.

 

Dean Shomshak



#2704 pinecone

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Posted 04 June 2017 - 01:12 PM

 Sounds very cool, hopefully a "doable" expirament can be designed. Maybe negative curvature, negative energy, and "dark mass" can be bundled up based on the outcomes. :yes:  And yeah Phase changes are a wide spead effect, that I at least find very mysterious, a fundamental quality found all over the place...the whole of reality may "simply" going through the equivelent of an ice cube melting. :rofl:  It's just hard to see from the inside. :winkgrin:


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#2705 DShomshak

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Posted 07 June 2017 - 04:58 PM

Heard this week on the radio, and read about in The Economist: LIGO has detected a third pulse of gravity waves. As The Economist notes, gravitational wave detection is transitioning from physics experiment -- just proving that the waves exist -- to astronomy, as a technique to observe events not observable in other ways.

 

Dean Shomshak


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#2706 Cancer

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Posted 07 June 2017 - 07:41 PM

The thing everyone is waiting for is completion of the third gravity-wave detector. That would will allow pinpointing in the sky of the events (with two detectors you can get only a stripe), which means you can turn other instruments on the location and see what else might be there.
... abnormal, non-Euclidean, and loathsomely redolent of spheres and dimensions apart from ours.

#2707 Old Man

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Posted 26 June 2017 - 02:58 PM

Tests of Raytheon high energy laser on Apache gunship "performs as expected"


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...and that's when the destruction began.

#2708 L. Marcus

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Posted 26 June 2017 - 03:00 PM

Blew up, did it?
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#2709 Christopher

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Posted 26 June 2017 - 03:20 PM

Blew up, did it?

But only on the right end of the beam, propably.



#2710 DShomshak

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Posted 05 July 2017 - 05:36 PM

The July, 2017 Scientific American has a feature article on primordial black holes as a candidate for dark matter. This was considered and rejected some time ago, but the authors point out that past studies that looked for MACHOs (MAssive Compact Halo Objects) through gravitational microlensing made certain assumptions that might not be justified. For one thing, their math says PBHs would be formed in fairly dense clusters rather than be evenly spread. They say their version also explains some other cosmic puzzles, such as ultra-faint dwarf galaxies, or the black holes detected by LIGO being in a mass range that astronomers didn't think could exist. The article includes possible observations that could confirm or deny the proposal.

 

Also, the lettercol includes a long letter from a bunch of distinguished cosmologists objecting to the February issue's article that said inflationary cosmology was a load of fetid dingo's kidneys. The authors say that inflation theory predictions match almost perfectly with a variety of subsequent observations, which is why most cosmologists now accept it. The article's authors riposte that the theory being defended is not the theory as it currently exists, and stand by their claim that inflation theory has ceased to be science. It's an interesting bit of scientific debate.

 

Dean Shomshak



#2711 Christopher

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Posted 15 July 2017 - 06:11 PM

Way back in 12th May 2017 we first dected signals from Ross 128. The time has come to take another look, using the Arecibo Radio Teleskope. Wich is the one one sensitive enough to actually detect these signals.

http://www.businessi...017-7?r=US&IR=T

 

The chance of it being a SETI answer is "very low, but not excludeable".


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#2712 L. Marcus

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Posted 16 July 2017 - 02:59 AM

Let's not bother -- it's probably a Devouring Swarm.
"Things would be much better if more things were on fire." -- lemming

"I may not be consistent, but I'm happily schizoid." -- "V"

"Trouble expands to fill the space available." -- Markdoc

Do you know what becomes of dead dreams?

#2713 Christopher

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Posted 16 July 2017 - 06:04 AM

Let's not bother -- it's probably a Devouring Swarm.

Well, I would like to know if I am about to be on anythings menu soon-ish.