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Feb
8
comment Is climate change caused by humans?
My "views" on climate are quite orthodox, e.g. ice ages from orbital forcing, $CO_2$ as the main factor, and I have supposed cosmic rays were at most just a small correction to this.
Feb
8
comment Is climate change caused by humans?
@honeste_vivere I have heard of at least three timescales from the cosmic-ray climate-theorists. There's the attempt to explain the warming of recent decades as due to quiet solar cycles; something about the little ice age and an extended medieval period of low solar activity, as shown by low sunspot numbers; and multi-million-year variations in cosmic-ray flux due to the sun passing between arms of the galaxy.
Feb
8
comment Is climate change caused by humans?
Cosmic rays don't matter as a direct source of energy if that's what you're thinking. The idea is that as they pass through the atmosphere they ionize molecules and create many charged particles that seed the formation of clouds. So when there are more cosmic rays reaching Earth, there should be more clouds, and more immediate reflection of solar radiation back into space and therefore less warming.
Feb
7
comment Cold Solid Matter at the End of a Black Hole's Acceleration Disk?
Maybe I should emphasize, Bose condensation is not fusion, Bose condensation would just be a different way for atoms to get very close. But the atoms have to be the same type, and even then, it only happens for certain types of atom.
Feb
7
comment Cold Solid Matter at the End of a Black Hole's Acceleration Disk?
Bose condensation only happens for specific atoms en.wikipedia.org/wiki/Bose–Einstein_condensate#Isotopes and it's very delicate. Nuclear fusion in an atomic BEC would be even more delicate, if it's even possible.
Feb
7
comment Cold Solid Matter at the End of a Black Hole's Acceleration Disk?
@Jen The first part is sort of what happens when a star forms. The atoms in the protostellar nebula of gas, that is spread across space, all fall towards the center of gravity. That's how they get their kinetic energy. The nebula shrinks to star size and each nucleus then spends millions or billions of years inside, ricocheting from others until they have a head-on collision and fuse.
Feb
7
comment Cold Solid Matter at the End of a Black Hole's Acceleration Disk?
@dmckee I think this is half of a personal theory about emission (of light? of jets?) from near black holes.
Feb
7
answered Cold Solid Matter at the End of a Black Hole's Acceleration Disk?
Feb
7
answered Is climate change caused by humans?
Feb
5
comment The naive idea of the big bang
@CuriousOne That's not a reasonable comparison. An explosion in the conventional sense is a type of physical process for which there are models. It is completely reasonable to wonder whether the expanding universe was produced by an explosion. And I have noticed that exposition regarding this issue does not say "why primordial explosion is a physically wrong idea", it says "why big bang theory isn't a primordial explosion theory".
Feb
5
comment Multiverse fictional constraints
Multiverse just means any scenario with more than one universe. Two is more than one, so the "theory" that reality consists of "this universe" plus "Dragonball Z" is a multiverse theory, though not a popular one outside of Dragonball fandom... As for the many-worlds interpretation of QM, that's always relative to some specific theory like "standard model + gravity"... "All logically possible worlds exist" is multiverse maximalism, found e.g. in David Lewis and Max Tegmark, and is far beyond the limited multiverse notions that are employed by some physicists.
Feb
5
comment The naive idea of the big bang
@CuriousOne Sophistication is relative. The minimum I was after is a quantitative model based on laws or principles. The average "naive big bang theorist" is just a layperson thinking intuitively.
Feb
5
asked The naive idea of the big bang
Feb
3
answered publication ethics
Feb
2
comment Big Bang Quarks Travelling at Light Speed
@dmckee the source is right at the end, "pela"
Feb
1
comment Can Quantum Field Theory be right even though it doesn't include gravity?
otherwise, I would say that as a quantum theory of gravity, string theory is in much better shape than AS or LQG. In string theory, gravity comes automatically with fermions and gauge bosons; and in principle, the geometry and topology of the extra dimensions actually determines all the particle masses, couplings, etc. So it is quite compelling. But in practice there are a zillion possibilities and it's very hard to calculate anything. There is progress, there are partial successes, but there is so far no "standard stringy vacuum" in the way that QFT produced a "standard model".
Feb
1
comment Can Quantum Field Theory be right even though it doesn't include gravity?
@Nick the leading attempt to make gravity work as a QFT is scholarpedia.org/article/Asymptotic_Safety_in_quantum_gravity ... It has the curious claim to fame of having predicted the Higgs boson mass arxiv.org/abs/0912.0208
Jan
31
comment What effects would a finding of Gravitational Repulsion Between Matter and Anti-Matter in the ALPHA Experiment have on Mainstream Theory?
@Lewis Miller - arxiv.org/abs/1110.3054 - I have not read this paper
Jan
29
awarded  Civic Duty
Jan
26
comment Why is the “expansion postulate” a postulate of quantum mechanics?
I never heard of this didactic strategy before. It seems to be a way of declaring "we won't be looking at cases where this isn't true". physics.stackexchange.com/questions/68822/…