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Ask Slashdot: Best Book For 11-Year-Old Who Wants To Teach Himself To Program?

Quaoar Re:Datasheet (525 comments)

Or the Unabomber...

more than 2 years ago
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Findings Cast Doubt On Moon Origins

Quaoar Re:Not a contradiction (233 comments)

The preferred giant impact model has a Mars-sized impactor with a core-to-mantle ratio equal to the Earth's, with approximately 30% of its mass being in an iron core (http://adsabs.harvard.edu/abs/2004Icar..168..433C). Mars is ~1/6th the Earth's mass. In this impact, the material liberated that eventually forms the moon is iron poor, as the iron core of the impactor sinks into the Earth. That has been the interpretation as to why the Moon's iron core is so small (no more than 3% its total mass), so in this sense the giant impact model produces a satisfactory outcome. Some fraction of the lunar surface is accumulated over the 4 billion years since the Moon formed, but this layer is thought to be very thin, and the meteorites + Apollo samples we use to measure the moon's isotopic ratios come from a range of depths that probe significantly deeper than this surface layer. The fine-tuning argument comes from the fact that for an arbitrary combination of impactor + Earth mass, impact angle, velocity, etc, you'd expect a scatter in the isotope ratios consistent with the typical scatter measured between other bodies in the solar system (say that between Mars and the Earth). Fine-tuning is often employed in intelligent design arguments as they rely on the anthropic principle, but as there's no reason to require the Earth and Moon to have identical isotopic compositions to explain the existence of life, there is no particular reason to favor any particular outcome over the myriad of other outcomes for this particular measurement.

more than 2 years ago
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Findings Cast Doubt On Moon Origins

Quaoar Re:Not a contradiction (233 comments)

The problem is that the ratio of Earth's mantle to Theia's mantle matters in the combination, even if mixing is efficient. The Earth's mantle is fully convective, and around 6 times the mass of the impactor's mantle, which means that you have to really fine-tune the conditions to achieve the exact right mixture. A good analogy would be trying to mix milk and water in a glass such that the fluid that splashes out of the glass has the same fraction of milk to water as the fluid remaining in the glass. With the original Oxygen isotope constraint, 95%+ of the lunar mantle needed to originate from the Earth, which is in direct conflict with the giant impact simulations that have been performed (which find 80% coming from the *impactor*), even for iron-rich impactors that preferentially remove Earth's mantle. This new constraint, if I am reading the paper correctly, is even stronger than the Oxygen isotope constraint, being at the part per million level rather than the part per ten thousand level.

more than 2 years ago
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Findings Cast Doubt On Moon Origins

Quaoar Re:Not a contradiction (233 comments)

This doesn't work. The fractional element abundances depend not only on the location in the protoplantery disk, but on the timescales of accretion, which depend on the mass of the object accreting. Thus, even if you formed Theia in L4/L5, the isotopic ratios should be different, as the two objects will have different masses.

more than 2 years ago
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Camera Can See Around Corners

Quaoar Re:Mmm, paywall. (64 comments)

If only someone invented some sort of laser that would allow me to see behind this paywall...

more than 2 years ago
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Chase Bank May Drop Support of Chrome, Opera

Quaoar Chase blows (398 comments)

Fuck Chase...I had Wamu before they were swallowed by Chase, and Wamu's website was FAR superior to the ancient web banking that Chase offers. I have to click through 5 screens just to transfer money across accounts with chase, and I doubt they're not using anything more sophisticated than plain https, so any BS reason they offer for not supporting certain modern browsers is just that...BS.

about 4 years ago
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People Emit Visible Light

Quaoar Re:nothing special... (347 comments)

These results are specifically about the deviation of the spectrum produced by a human from a black body, and how that varies throughout the day. For a blackbody, the number of photons coming out as visible radiation is 1/10^3000 the total number (assuming a body temperature of ~280K, the number is so tiny because visible photons fall into the exponential Wein tail of the BB distribution), so you would naÃvely predict that no human has ever emitted a visible photon. Ever. So yes, it is something special.

more than 4 years ago
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Earth Could Collide With Other Planets

Quaoar Re:Or earth could turn into an elephant (255 comments)

I realize the linked article doesn't have the 1% figure, here's a better article:

http://www.universetoday.com/2009/06/10/wild-little-mercury-to-cause-interplanetary-smashup-maybe/

more than 5 years ago
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Earth Could Collide With Other Planets

Quaoar Re:No big deal here (255 comments)

Being able to quantify the odds is an achievement. Why belittle it? Where's your paper on the multi-billion year evolution of the solar system?

more than 5 years ago
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Earth Could Collide With Other Planets

Quaoar Re:Or earth could turn into an elephant (255 comments)

1% in 5 billion years is actually fairly high...you're talking some major solar system engineering if Mercury's orbit suddenly starts to look funny.

more than 5 years ago
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Black Hole Swallows Star

Quaoar Bad Title (166 comments)

Quoth the conclusion of the referenced paper:

"These possibilities, combined with the observation that the
disrupted object be a carbon-rich star, rather than a normal
main sequence one appear to make the case for tidal disruption
somewhat contrived. Nonetheless, with only one object, and
thus an essentially unconstrained rate and space density for
such events, it remains a possibility."

So, while tidal disruption is a possibility, it is not the favored scenario.

more than 5 years ago
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Wolfram Alpha Launches Tonight, On Camera

Quaoar How you can use it now... (218 comments)

Here's how to bring up the real search page:

http://www.wolframalpha.com/input/?

more than 5 years ago
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Of the D.C. v. Heller decision, I think it's a

Quaoar Re:why did it take so long? (1308 comments)

Remember that 4 justices did oppose, and the court was more liberal before Bush's appointments. It's possible that no one wanted to challenge the law until the chances of it being overturned were good.

about 6 years ago

Submissions

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Quaoar Quaoar writes  |  more than 7 years ago

Quaoar writes "This is just a plea to the Slashdot editors to post any submission related to Saddam's execution so there might be an intelligent discussion about the topic. I think neglecting to post this story shows a lack of backbone. PLEASE post it. Thanks."

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