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Old 2019-10-01, 23:16   #2587
Dr Sardonicus
 
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Quote:
Originally Posted by rogue View Post
This article had a link to another article that might be of interest:

A crash of stars reveals the origins of heavy elements
Quote:
Last August 17, at 8:41 a.m. Eastern time, Earth received a message from deep space that solved — perhaps — a decades-old puzzle.

The message began as a subtle quiver in the fabric of space, a gravitational wave. It grew to a cosmic cacophony that included gamma rays, radio waves and visible light. It all emanated from a galaxy roughly 130 million light-years away, where the dense cores of two long-dead stars collided. In the debris from the crash, some of the heaviest atoms in the cosmos, such as gold, platinum and uranium, were born.
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Old 2019-10-04, 19:58   #2588
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It's been said that Octopi provide the closest thing we have on earth to an "alien intelligence", one which evolved quite distinctly from that of the mammalian lineage. If they really do dream like we do, that would be a fascinating example of convergent evolution. It's easy to understand how adaptations which solve specific problems related to basic life processes (e.g. the various senses, locomotion, etc.) can evolve convergently - they solve the same problem, and "form follows function" - but "what problem does dreaming solve?" is a far less obvious candidate for such convergence. Perhaps the linkage between dreaming and imagination is key here - a crucial marker of higher intelligence is the ability to imagine, i.e. "to run simulations", as it were, and dreams appear to be an unconscious-state version of that - while we sleep our physical bodies engage in vital maintenance activities, and our brain runs simulations which help it consolidate memories based on experiences undergone during wakefulness. Convergent evolution in the latter realm would imply that such "memory maintenance" during sleep is a vital part of higher intelligence.

But we really need some way to monitor brainwaves in Octopi to better establish the "dreaming" hypothesis.

Re. Dr.S' bonus link, "A Crash of Stars" sounds like a collective noun - I like it!
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Old 2019-10-07, 13:44   #2589
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Decades-Old Code Is Putting Millions of Critical Devices at Risk

Loch Ness Monster: how eDNA helps us discover what lurks beneath

Last fiddled with by Uncwilly on 2019-10-08 at 01:16 Reason: Removed all of the referrer garbage on end of link.
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Old 2019-10-07, 14:14   #2590
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Quote:
Originally Posted by ewmayer View Post
It's been said that Octopi provide the closest thing we have on earth to an "alien intelligence", one which evolved quite distinctly from that of the mammalian lineage. If they really do dream like we do, that would be a fascinating example of convergent evolution. It's easy to understand how adaptations which solve specific problems related to basic life processes (e.g. the various senses, locomotion, etc.) can evolve convergently - they solve the same problem, and "form follows function" - but "what problem does dreaming solve?" is a far less obvious candidate for such convergence. Perhaps the linkage between dreaming and imagination is key here - a crucial marker of higher intelligence is the ability to imagine, i.e. "to run simulations", as it were, and dreams appear to be an unconscious-state version of that - while we sleep our physical bodies engage in vital maintenance activities, and our brain runs simulations which help it consolidate memories based on experiences undergone during wakefulness. Convergent evolution in the latter realm would imply that such "memory maintenance" during sleep is a vital part of higher intelligence.

But we really need some way to monitor brainwaves in Octopi to better establish the "dreaming" hypothesis.
The idea of an octopus dreaming came up on this recent installment of the PBS series NATURE, Making Contact.

The page includes a complete transcript. A text search on "dreaming" turns up the relevant passage pretty quickly, also a video clip of the sleeping octopus changing colors.
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Old 2019-10-07, 15:43   #2591
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Quote:
have a rest mass of a mere 510,000 eV~511keV
https://en.wikipedia.org/wiki/Electron_rest_mass
Small change, to be sure, compared to the other article errors. The ~0.2% rounding error may seem small, but it is both unnecessary, saving zero characters in the expression, and rather harsh treatment for a measurement that's been made to about 2 ppb estimated accuracy, and whose expression as 511keV instead of 510keV is within 2.1ppm of the measured value, ~10,000 times less error.

Last fiddled with by kriesel on 2019-10-07 at 15:54
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Old 2019-10-08, 12:29   #2592
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Originally Posted by kriesel View Post
(quoting ewmayer's corrected quotation here from the article here
Quote:
have a rest mass of a mere 510,000 eV~511keV
https://en.wikipedia.org/wiki/Electron_rest_mass
Small change, to be sure, compared to the other article errors. The ~0.2% rounding error may seem small, but it is both unnecessary, saving zero characters in the expression, and rather harsh treatment for a measurement that's been made to about 2 ppb estimated accuracy, and whose expression as 511keV instead of 510keV is within 2.1ppm of the measured value, ~10,000 times less error.
It occurred to me to wonder how this happened. One obvious explanation is, the actual value is approximately 0.5109989 MeV, which is a bit less than 0.511 MeV, so the inaccurate figure could be the result of truncation rather than rounding. Whether the article's author committed the blunder or copied it from someone else, is more than I can say.

A bit harder to explain (but a possible copy-paste source of the blunder) is the following, which occurs in Stability Valley:
Quote:
A beta decay costs only 0.511 MeV (510,000 electron volts) much less than the 7 to 8 million electron volts (MeV) required for the expulsion of a neutron, the competitng process.
BTW, in the older physics textbooks I consulted the (rest) mass of the electron is given as 9.11 x 10-28 g which is correct to 3 sig figs, rounded down from 9.1093.... The oldest of these books, my dad's copy of Hausmann and Slack, has a copyright date of 1939.
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Old 2019-10-08, 14:00   #2593
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Quote:
Originally Posted by Dr Sardonicus View Post
BTW, in the older physics textbooks I consulted the (rest) mass of the electron is given as 9.11 x 10-28 g which is correct to 3 sig figs, rounded down from 9.1093....
Oops, I meant "rounded up" or just plain "rounded." That's not a typo, that's a wrong-word error...
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Old 2019-10-08, 19:09   #2594
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Post-empirical science is an oxymoron, and it is dangerous | Aeon Essays -- On the "multiverse is real" PR-wankery by the usual suspects, the theoretical (meta)physicists. Hey, why should string theorists have all the pseudoscientific fun?
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Old 2019-10-08, 23:35   #2595
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A quote from Wiki on the the Scopes Trial:

"Stewart objected for the prosecution, demanding to know the legal purpose of Darrow's questioning. Bryan, gauging the effect the session was having, snapped that its purpose was "to cast ridicule on everybody who believes in the Bible". Darrow, with equal vehemence, retorted, "We have the purpose of preventing bigots and ignoramuses from controlling the education of the United States."[39]"

Everyone needs to choose a side but making informed choices seems to be the catch. What is information, where can it be found and how do you interpret it once you think you've recognized some?


Regarding the excellent article:
https://www.quantamagazine.org/math-...itry-20190918/
I followed up on the proof of the result which was an interesting read.
Noise exists everywhere, you can't suppress it but you can determine what is important and what is not by building upon simplicity.

Last fiddled with by jwaltos on 2019-10-08 at 23:52 Reason: clarification
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Old 2019-10-09, 12:06   #2596
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Quote:
Originally Posted by ewmayer View Post
Post-empirical science is an oxymoron, and it is dangerous | Aeon Essays -- On the "multiverse is real" PR-wankery by the usual suspects, the theoretical (meta)physicists. Hey, why should string theorists have all the pseudoscientific fun?
Fascinating. I was unaware of the "bottle versus beam" discrepancy in free neutron half-life.

As it happens, I was aware that another radioactive decay process -- also involving the weak force -- varies due to a known mechanism. This process is known as electron capture, K-capture, or L-capture. It occurs when the nucleus of an atom absorbs, or captures, an electron from that atom. The mechanism is variability in the atom's electronic state -- chemical bonds, for example.

It appears that "beam" neutrons "last longer." The figures given here are

\text{Most precise Bottle: }\tau_{n}\;=\; 878.5\;\pm\;0.8 s \\ \text{Most precise Beam: }\tau_{n}\;=\; 887.1\;\pm\;2.2 s\text{ Yue et al., Phys. Rev. Lett.  111, 222501 (2013)}

(The article also outlines the two methods.)

String "theory" and "parallel universes" seem to be getting cast in the role assigned to electricity by Ambrose Bierce in The Devil's Dictionary. His definition begins,
Quote:
ELECTRICITY, n. The power that causes all natural phenomena not known to be caused by something else. [....]
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