Apr. 22nd, 2010

Hypernova!

Apr. 22nd, 2010 07:57 am
nancylebov: blue moon (Default)
The super-supernova SN2007bi is an example of a "pair-instability" breakdown, and that's like calling an atomic bomb a "plutonium-pressing" device. At sizes of around four megayottagrams (that's thirty-two zeros) giant stars are supported against gravitational collapse by gamma ray pressure. The hotter the core, the higher the energy of these gamma rays - but if they get too energetic, these gamma rays can begin pair production: creating an electron-positron matter-antimatter pair out of pure energy as they pass an atom. Yes, this does mean that the entire stellar core acts as a gigantic particle accelerator.

The antimatter annihilates with its opposite, as antimatter is wont to do, but the problem is that the speed of antimatter explosion - which is pretty damn fast - is still a critical delay in the gamma-pressure holding up the star. The outer layers sag in, compressing the core more, raising the temperature, making more energetic gamma rays even more likely to make antimatter and suddenly the whole star is a runaway nuclear reactor beyond the scale of the imagination. The entire thermonuclear core detonates at once, an atomic warhead that's not just bigger than the Sun - it's bigger than the Sun plus the mass of another ten close by stars.
The entire star explodes. No neutron star, no black hole, nothing left behind but an expanding cloud of newly radioactive material and empty space where once was the most massive item you can actually have without ripping space. The explosion alone triggers alchemy on a suprasolar scale, converting stars' worth of matter into new radioactive elements.


Link from Geek Press.

There are a lot more kinds of nova than I realized.

The only gamma ray burster I can' think of in science fiction is in Egan's Diaspora.

Hypernova!

Apr. 22nd, 2010 07:57 am
nancylebov: (green leaves)
The super-supernova SN2007bi is an example of a "pair-instability" breakdown, and that's like calling an atomic bomb a "plutonium-pressing" device. At sizes of around four megayottagrams (that's thirty-two zeros) giant stars are supported against gravitational collapse by gamma ray pressure. The hotter the core, the higher the energy of these gamma rays - but if they get too energetic, these gamma rays can begin pair production: creating an electron-positron matter-antimatter pair out of pure energy as they pass an atom. Yes, this does mean that the entire stellar core acts as a gigantic particle accelerator.

The antimatter annihilates with its opposite, as antimatter is wont to do, but the problem is that the speed of antimatter explosion - which is pretty damn fast - is still a critical delay in the gamma-pressure holding up the star. The outer layers sag in, compressing the core more, raising the temperature, making more energetic gamma rays even more likely to make antimatter and suddenly the whole star is a runaway nuclear reactor beyond the scale of the imagination. The entire thermonuclear core detonates at once, an atomic warhead that's not just bigger than the Sun - it's bigger than the Sun plus the mass of another ten close by stars.
The entire star explodes. No neutron star, no black hole, nothing left behind but an expanding cloud of newly radioactive material and empty space where once was the most massive item you can actually have without ripping space. The explosion alone triggers alchemy on a suprasolar scale, converting stars' worth of matter into new radioactive elements.


Link from Geek Press.

There are a lot more kinds of nova than I realized.

The only gamma ray burster I can' think of in science fiction is in Egan's Diaspora.
nancylebov: (green leaves)
http://www.medicalnewstoday.com/articles/185482.php

A very successful mouse study of a drug that keeps a wide variety of cancers from spreading.

This kind of thing is of huge importance systemically as well as individually-- with the birth rate dropping sharply, there won't be enough hands and minds needed to take care of debilitated people unless there's much better medical tech.

Link thanks to [livejournal.com profile] theweaselking.
nancylebov: blue moon (Default)
http://www.medicalnewstoday.com/articles/185482.php

A very successful mouse study of a drug that keeps a wide variety of cancers from spreading.

This kind of thing is of huge importance systemically as well as individually-- with the birth rate dropping sharply, there won't be enough hands and minds needed to take care of debilitated people unless there's much better medical tech.

Link thanks to [livejournal.com profile] theweaselking.
nancylebov: blue moon (Default)
Quantum explanation for muscle contraction
Tieyan Si at the Max Planck Institute for Complex Systems in Dresden, Germany, has created a quantum model of muscle behaviour. His idea is that myosin, the molecular motor responsible for muscle contraction, is essentially a quantum object and that its behaviour is best described by quantum mechanics.

Does this kind of thing imply that you can't predict good simulations of human brains by comparing the number of neurons to Moore's Law? There are a lot of quanta, but (afaik) they're simple and statistically predictable. If brains are using quantum effects, how much is this likely to add to the amount of computing needed?

Yet another link thanks to Geek Press.
nancylebov: (green leaves)
Quantum explanation for muscle contraction
Tieyan Si at the Max Planck Institute for Complex Systems in Dresden, Germany, has created a quantum model of muscle behaviour. His idea is that myosin, the molecular motor responsible for muscle contraction, is essentially a quantum object and that its behaviour is best described by quantum mechanics.

Does this kind of thing imply that you can't predict good simulations of human brains by comparing the number of neurons to Moore's Law? There are a lot of quanta, but (afaik) they're simple and statistically predictable. If brains are using quantum effects, how much is this likely to add to the amount of computing needed?

Yet another link thanks to Geek Press.
nancylebov: (green leaves)
The article

The book. Details about expanded paperback edition.

There was a handy overview of all the common ideas that got debunked, and I can't find it again, but the major point for me is that the shooters weren't bullied. They were moderately popular, and they were bullies themselves.

The reason I had the url for the article on my clipboard is that I'd been reading discussions of bullying, and word about what the shooters were really like doesn't seem to have gotten out.

It is perhaps unsurprising that the initial reaction when it was believed that the shooters were bullied was for weird kids to get bullied more.

Addeendum: The summary. Link found by [livejournal.com profile] andrewducker.
nancylebov: blue moon (Default)
The article

The book. Details about expanded paperback edition.

There was a handy overview of all the common ideas that got debunked, and I can't find it again, but the major point for me is that the shooters weren't bullied. They were moderately popular, and they were bullies themselves.

The reason I had the url for the article on my clipboard is that I'd been reading discussions of bullying, and word about what the shooters were really like doesn't seem to have gotten out.

It is perhaps unsurprising that the initial reaction when it was believed that the shooters were bullied was for weird kids to get bullied more.

Addeendum: The summary. Link found by [livejournal.com profile] andrewducker.
nancylebov: blue moon (Default)
I have a notion that there's a bias against Chaotic Evil player characters because the easiest way to show you're Chaotic Evil is to attack someone in your party. On the other hand, there are easy ways to demonstrate other alignments without a hign social cost.

I'm not so much suggesting that CE characters are disliked as hypothesizing that they're more rarely played than other alignments. Am I right?
nancylebov: (green leaves)
I have a notion that there's a bias against Chaotic Evil player characters because the easiest way to show you're Chaotic Evil is to attack someone in your party. On the other hand, there are easy ways to demonstrate other alignments without a hign social cost.

I'm not so much suggesting that CE characters are disliked as hypothesizing that they're more rarely played than other alignments. Am I right?

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