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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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 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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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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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.

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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

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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.businessinsider.de/ross-128-red-dwarf-radio-signals-mystery-2017-7?r=US&IR=T

 

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

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The July 15-21 issue of the Economist has an article about gas giant planets. Exoplanet studies show two distinct classes of exo-jovians: one set with masses up to four times that of Jupiter, and another with masses 8-20x that of Jupiter. A planetary system rarely has members in both mass ranges.

 

There are also two competing theories about how jovians form. One theory says a core of rock and ice forms, and the nascent planet then sweeps up copious gas. The other theory holds that instabilities form in the protoplanetary cloud and a big wad of dust and gas collapses all at once to form a jovian world.

 

A group of astronomers led by Vardan Adibekyan, of the Astrophysics and Space Science Institute in Porto, Portugal, proposes a connection between these two distinctions. Adibekyan and his colleagues note that the higher-mass jovians tend to occur around stars with low metallicities (to astronomers, "metals" are any element past hydrogen and helium), while the smaller jovians orbit higher-metallicity stars.

 

They propose that around the low-metal stars, there isn't enough dust and ice to form cores large enough to "snowball" by sucking up more and more gas. At least, it won't happen fast enough; the new star will blow away the gas before accretion goes very far. Any jovians will have to form through the one-step collapse method.

 

As the article notes, that doesn't explain why high-metal stars only have the smaller, core-accretion jovians: "Core formation does not obviously preclude a nebula breaking up into gas clumps as well. Such mysteries are the stuff of science. As the cliché has it, more research is needed."

 

Dean Shomshak

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The July 15-21 issue of the Economist has an article about gas giant planets. Exoplanet studies show two distinct classes of exo-jovians: one set with masses up to four times that of Jupiter, and another with masses 8-20x that of Jupiter. A planetary system rarely has members in both mass ranges.

 

There are also two competing theories about how jovians form. One theory says a core of rock and ice forms, and the nascent planet then sweeps up copious gas. The other theory holds that instabilities form in the protoplanetary cloud and a big wad of dust and gas collapses all at once to form a jovian world.

 

A group of astronomers led by Vardan Adibekyan, of the Astrophysics and Space Science Institute in Porto, Portugal, proposes a connection between these two distinctions. Adibekyan and his colleagues note that the higher-mass jovians tend to occur around stars with low metallicities (to astronomers, "metals" are any element past hydrogen and helium), while the smaller jovians orbit higher-metallicity stars.

 

They propose that around the low-metal stars, there isn't enough dust and ice to form cores large enough to "snowball" by sucking up more and more gas. At least, it won't happen fast enough; the new star will blow away the gas before accretion goes very far. Any jovians will have to form through the one-step collapse method.

 

As the article notes, that doesn't explain why high-metal stars only have the smaller, core-accretion jovians: "Core formation does not obviously preclude a nebula breaking up into gas clumps as well. Such mysteries are the stuff of science. As the cliché has it, more research is needed."

 

Dean Shomshak

So basically having Metals around to form a solid core means counter-intuitively a smaler gas giant.

 

Since all the exo-Jovians are so much bigger, does this mean Jupiter is a "super dense core Gas Giant"? The Jovians could thus be a viable way to define the stellar generation (and thus metal content) of exo-systems. Wich in turn affects likelyhood of life.

 

Maybe there is a interaction with teh weather on Jovians? Maybe heavier core Jovians have stronger natural weather.

And as a result, the amosphere is blow off into space until it reaches a "equilibrium"?

Escape Velocity on Jupiter is given as about 60 km/s. And on a larger giant the weather might get bad enough that the atmosphere reaches escape velocity.

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Maybe there is a interaction with teh weather on Jovians? Maybe heavier core Jovians have stronger natural weather.

And as a result, the amosphere is blow off into space until it reaches a "equilibrium"?

Escape Velocity on Jupiter is given as about 60 km/s. And on a larger giant the weather might get bad enough that the atmosphere reaches escape velocity.

Not going to happen. 60 km/sec is hypersonic in just about everything short of nuclear matter, much greater than the speed of sound. You aren't going to get an atmosphere generating even modestly supersonic bulk motions by itself. (Yes, lightning generates thunder through electric discharge which is supersonic, but that's very local and not a bulk motion)

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That is one of Larry Nivens concepts as well. :winkgrin:  Insane luck Is our "alien super power" :rockon:

Actually by the parameters Niven established any and all intelligent races would have insanely high luck to have been able to evolve to intelligence. Apparently this was another "captain obvious" level issue Niven couldn't see. Kind of like how he said pickpocketing was widespread on future earth due to overcrowding. I guess his awesome intellect couldn't figure out that some folks might put a chain on their wallets. Like the people who make chain wallets did.

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