Search found 196 matches

by drachefly
Mon May 04, 2015 6:33 pm UTC
Forum: Mathematics
Topic: Can anyone solve this probability problem?
Replies: 15
Views: 2968

Re: Can anyone solve this probability problem?

>-) wrote:to be clear, the k crucibles are created each with an k-sided dice if the prime dice rolls k?


I thought the first step was the number of iterations. Otherwise the center one is just like the others.
by drachefly
Mon May 04, 2015 5:35 pm UTC
Forum: Science
Topic: Constants and physical significance
Replies: 12
Views: 3459

Re: Constants and physical significance

Also, Wikipedia disagrees with the neutron decay time I quoted earlier - but it's still a human timescale, around 15 minutes instead of 10. The half-life of a free neutron is around 10 minutes, but its mean lifetime is around 15 minutes. Ah! I know the difference, but it didn't even occur to me tha...
by drachefly
Mon May 04, 2015 5:33 pm UTC
Forum: Mathematics
Topic: Lowest Common Multiple - LCM
Replies: 6
Views: 2074

Re: Lowest Common Multiple - LCM

Another example would be when things with different periods interact, what the overall resulting period is. I'm having a bit of trouble finding examples that are neither trivial (weeks being 7 days long makes this too easy) or too messy (months and even years are erratic).
by drachefly
Mon May 04, 2015 4:47 pm UTC
Forum: Mathematics
Topic: Time/energy required to cool tool steel
Replies: 5
Views: 2993

Re: Time/energy required to cool tool steel

37C is rather conservative for 'safe to touch'. Even with a metal, 45C should be safe to touch. It may not seem like that big a deal, but with exponential slowdown in cooling rates it could shave off a noticeable amount of time. Also, the outer surface will be cooler than the average, and that's wha...
by drachefly
Sat May 02, 2015 10:59 pm UTC
Forum: Science
Topic: Constants and physical significance
Replies: 12
Views: 3459

Re: Constants and physical significance

Well, 'spading' is gaming parlance (some games, anyway) for doing SCIENCE and figuring out the rules without being told. -- back on-topic -- The Lambda, Sigma, and Xi have finger-scale lengths. The charged pion is 2.6*10^-8 seconds, so that's around a meter. The longer Kaon lifetime is similar. Muon...
by drachefly
Fri May 01, 2015 5:38 pm UTC
Forum: Mathematics
Topic: What are monster groups and why do they exist?
Replies: 7
Views: 3092

Re: What are monster groups and why do they exist?

I think the more interesting question is why there isn't an infinite number of sporadic groups, or an infinite number of infinite families of groups. Firstly, their are a countable infinite number of finite simple groups. This is essentially a consequence of the fact that the theorem is specificall...
by drachefly
Fri May 01, 2015 5:22 pm UTC
Forum: Science
Topic: Constants and physical significance
Replies: 12
Views: 3459

Re: Constants and physical significance

The half-life of a free neutron is 10.2 minutes, which is on a human time-scale, and that seems pretty close to fundamental.
by drachefly
Wed Apr 29, 2015 6:31 pm UTC
Forum: Science
Topic: Earth's trajectory if the sun disappeared...?
Replies: 48
Views: 11174

Re: Earth's trajectory if the sun disappeared...?

douglasm wrote:The geocentric model is not inertial, so it is actually not as valid as the solar one by relativity. Relativity states that all inertial reference frames are equally valid, not absolutely all reference frames.


That's special relativity. General relativity eases that restriction.
by drachefly
Wed Apr 29, 2015 6:25 pm UTC
Forum: Mathematics
Topic: What are monster groups and why do they exist?
Replies: 7
Views: 3092

Re: What are monster groups and why do they exist?

I think the more interesting question is why there isn't an infinite number of sporadic groups, or an infinite number of infinite families of groups. Why should there be one largest sporadic simple group? It's like - taking the primes analogy mentioned above - we discovered that every prime beyond s...
by drachefly
Mon Apr 27, 2015 5:09 pm UTC
Forum: Science
Topic: On friction
Replies: 17
Views: 4045

Re: On friction

Also, when you set up equations like this in class, you will want to represent most quantities with letters, not words, and you can define your variables first. I find it helpful to use words while I'm figuring out what I'm doing. I can switch over to letters once I'm familiar with the meaning of e...
by drachefly
Mon Apr 27, 2015 5:05 pm UTC
Forum: Mathematics
Topic: how to maximize number of beard states?
Replies: 8
Views: 2623

Re: how to maximize number of beard states?

I am very disappointed that 'beard' was literal and not jargon.
by drachefly
Thu Apr 16, 2015 5:54 pm UTC
Forum: Science
Topic: What would it be like to put a giant drop of water in a...
Replies: 15
Views: 5907

Re: What would it be like to put a giant drop of water in a.

This also occurs in Endymion.
by drachefly
Thu Apr 16, 2015 5:52 pm UTC
Forum: Science
Topic: Schrodinger's Cat Satire
Replies: 8
Views: 3614

Re: Schrodinger's Cat Satire

ahammel wrote:The cat is too warm to decohere, if memory serves.


Don't you mean, the cat is warm enough to decohere right away? Aside from that, what Mayor Mare Copper Bezel and quantropy said.
by drachefly
Thu Apr 16, 2015 5:51 pm UTC
Forum: Science
Topic: De Broglie Wavelength and humans
Replies: 13
Views: 5290

Re: De Broglie Wavelength and humans

There are so many more reasons that humans can't diffract, don't get hung up on that one.
by drachefly
Thu Apr 16, 2015 5:49 pm UTC
Forum: Mathematics
Topic: function points
Replies: 35
Views: 6915

Re: function points

f.point wrote:
drachefly wrote:If that's so, then the standard way of writing 5-sub-y would be "(0,5)". The standard way of writing 5-sub-x would be "(5,0)"

I see that you think my notation is not compatible with the classical mathematics !!!


No, I'm sure it is. I just don't know what you're talking about.
by drachefly
Wed Apr 15, 2015 5:05 pm UTC
Forum: Mathematics
Topic: Simple probability question - cards
Replies: 7
Views: 1967

Re: Simple probability question - cards

Ordinarily, the probability P of drawing an ace on the first try would merely be P = k/n, but it is an unevenly-distributed deck and so the true probability is slightly lower...I'll call it P1. By unevenly distributed do you mean that it has been shuffled in some inhomogeneous fashion? What happens...
by drachefly
Wed Apr 15, 2015 4:51 pm UTC
Forum: Mathematics
Topic: function points
Replies: 35
Views: 6915

Re: function points

If that's so, then the standard way of writing 5-sub-y would be "(0,5)". The standard way of writing 5-sub-x would be "(5,0)"

But what might X-sub-x mean?

Is Y-sub-x the line given by the following equation?

f(a) = a*(1,1)
by drachefly
Wed Apr 15, 2015 3:48 pm UTC
Forum: Science
Topic: Maxwell's demon -- consensus on disproofs?
Replies: 20
Views: 5202

Re: Maxwell's demon -- consensus on disproofs?

This scheme dissipates energy in the form of setting up the sensor and letting it trigger, and regains some of the free energy lost by taking advantage of transient imbalances which will occur on thermodynamically long timescales. So it's a really, really, really slow and inefficient pump. Seems to ...
by drachefly
Wed Apr 15, 2015 3:29 pm UTC
Forum: Science
Topic: Carnot limit of a solar cell
Replies: 30
Views: 6150

Re: Carnot limit of a solar cell

The two relevant temperatures are given by the energy distribution of the incoming photons and the energy distribution of the electrons in and around the junction. These latter are very close to the bulk temperature of the solar cell.
by drachefly
Thu Mar 05, 2015 12:11 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1489: "Fundamental Forces"
Replies: 93
Views: 27961

Re: 1489: "Fundamental Forces"

A particular particle can have a much stronger charge than it can have gravitational force of its own. That's a meaningful statement. Even aside from trying to compare “charge” with “force”, I’m not convinced it’s a particularly useful statement. For example, another specific particle—the neutron—h...
by drachefly
Thu Mar 05, 2015 11:58 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1478: "P-Values"
Replies: 34
Views: 12226

Re: 1478: "P-Values"

What is the exact statistical software I can use to test whether family A of snakes has lower muscle mass than families B and C using Bayesian methods, where I can just plug in a list of measurements, hit "go", and get an answer? There is not a thing in the world that can tell you that. I...
by drachefly
Wed Feb 25, 2015 11:34 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1491: "Stories of the Past and Future"
Replies: 99
Views: 35252

Re: 1491: "Stories of the Past and Future"

Lest Darkness Fall was not set in 1435 (1936-500 as on the chart). It is set starting 535. Anathem would be set outside the plane of the chart. if there were a time-travel story set in 1885 wherein they go back in time to 1855... I don't think I'd be able to tell the difference in the eras at all, a...
by drachefly
Tue Feb 24, 2015 12:54 pm UTC
Forum: Science
Topic: Teleporting inside a wall
Replies: 16
Views: 5363

Re: Teleporting inside a wall

In Stargate, ring teleporters swapped their contents.
by drachefly
Tue Feb 24, 2015 11:50 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1489: "Fundamental Forces"
Replies: 93
Views: 27961

Re: 1489: "Fundamental Forces"

I looked up just exactly how the weak force causes beta decay. Really, a down quark in a neutron decays into an up quark and a W boson. Then the W boson decays into an electron and an electron antineutrino. Because the W boson is the mediator of the weak force, you can kind of think of the weak for...
by drachefly
Fri Feb 20, 2015 3:25 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1489: "Fundamental Forces"
Replies: 93
Views: 27961

Re: 1489: "Fundamental Forces"

The weak interaction describes how and when the fairly-rigidly-defined type boundaries that underlie the structure of matter leak.
by drachefly
Tue Feb 17, 2015 11:07 pm UTC
Forum: Science
Topic: Fuck Dark Matter; It's a sprinkler, not a whirlpool.
Replies: 135
Views: 27615

Re: Fuck Dark Matter; It's a sprinkler, not a whirlpool.

In the example, 'Skolnick's lovely asistant Gmal' is not in a P orbit. You need a lot more spherical harmonics to describe the location of a human on the surface of the Earth than a lonely L=1 M = 0 mode.
by drachefly
Mon Feb 16, 2015 3:52 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0526: "Converting to Metric"
Replies: 429
Views: 92198

Re: 0526: "Converting to Metric"

I had to choose between common sense and being exact at a couple of place so I choose exactitude.( ex : 110 kph is actually 68 mph)


yes, I found your round-trip converting 65 mph to 68 mph amusing.
by drachefly
Sat Feb 14, 2015 3:33 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1486: "Vacuum"
Replies: 44
Views: 11705

Re: 1486: "Vacuum"

For a fan, that's really high speed.
by drachefly
Fri Feb 13, 2015 9:36 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1486: "Vacuum"
Replies: 44
Views: 11705

Re: 1486: "Vacuum"

Honestly, because it's the first one I clicked on on wikipedia. I knew about turbomolecular pumps, but that felt more pumpish and less cleanerish, so I had a quick skim of the ultra high vacuum article for inspiration. Ion Pumps and Turbo Molecular Pumps are two really, really different things. A T...
by drachefly
Wed Feb 04, 2015 7:28 pm UTC
Forum: Science
Topic: Slowing down earth rotation: would fixed rocket engine help?
Replies: 3
Views: 1930

Re: Slowing down earth rotation: would fixed rocket engine h

Most of the bright light from the rocket escapes, so you'll have a little effect. A very little.
by drachefly
Tue Jan 27, 2015 12:44 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1478: "P-Values"
Replies: 34
Views: 12226

Re: 1478: "P-Values"

This really missed the opportunity to consider numbers up closer to 1 and, as noted above, beyond. More seriously... Meanwhile, the Bayesian statisticians are laughing. Because they don't have anything more useful to add? :wink: Aside from providing an odds ratio by which you should update, which wi...
by drachefly
Tue Jan 13, 2015 3:09 pm UTC
Forum: Science
Topic: A Little Thought About Nomadic Planets
Replies: 13
Views: 4146

Re: A Little Thought About Nomadic Planets

Hmm. Out of curiosity, can a planet of the right size continue to give off heat as a result of gravitational squeezing, but not be large enough to initiate fusion? Will such a planet stop giving off heat eventually? My hunch is that you can't get heat from nothing forever, so, yes? It will slow dow...
by drachefly
Tue Dec 30, 2014 3:12 pm UTC
Forum: Science
Topic: Vertical farm energy calculator
Replies: 27
Views: 10638

Re: Vertical farm energy calculator

I wonder if you can use a color-splitting diffracting mirror to funnel just the sunlight that's at the right frequencies to the plants directly, thus avoiding the doubled conversion inefficiencies.

Since direct sunlight is collimated, it should be doable.
by drachefly
Tue Dec 30, 2014 3:09 pm UTC
Forum: Science
Topic: (New) Neutrinos = Tachyon?
Replies: 19
Views: 5558

Re: (New) Neutrinos = Tachyon?

Meaning flavor oscillations would statistically smooth out the results, with a tachyon flavor assumedly going > C and a bradyon flavor going < C. So you're not only proposing something going faster than light, but something that can oscillate back and forth across the lightspeed barrier? And switch...
by drachefly
Wed Dec 17, 2014 12:21 pm UTC
Forum: Science
Topic: Fingers on Humans
Replies: 80
Views: 18525

Re: Fingers on Humans

I can easily detect extra tension getting my thumb to touch my pinky, but it's nowhere near the limit. I max out abut two additional finger-widths over.
by drachefly
Thu Dec 04, 2014 7:22 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1455: "Trolley Problem"
Replies: 172
Views: 50885

Re: 1455: "Trolley Problem"

Folks, you've got to work in the least convenient possible world. That means no, no nukes are available.
by drachefly
Thu Dec 04, 2014 6:49 pm UTC
Forum: Science
Topic: Tiny medieval units
Replies: 32
Views: 8538

Re: Tiny medieval units

I have to say, this thread is absolutely fascinating from many perspectives, and yet every time I see the topic I imagine phalanxes of inch-high soldiers. Yeah, I went the other way and kept thinking odd groups of only two or three infantrymen. Every time I see the topic title. And similarly, I fin...
by drachefly
Thu Dec 04, 2014 5:15 pm UTC
Forum: Science
Topic: Schrodinger Cat Disproof (Samuel Jacobs)
Replies: 88
Views: 21291

Re: Schrodinger Cat Disproof (Samuel Jacobs)

Paragraph 2: Yes, neutrinos present a non-fundamental limit on the size*duration of a coherent state. However, neutrinos do not interact rapidly with the cat (to put it mildly), so this degradation will not be very quick. Easily long enough to perform the experiment and run up against much more fund...
by drachefly
Sat Nov 22, 2014 1:18 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1450: "AI-Box Experiment"
Replies: 200
Views: 67756

Re: 1450: "AI-Box Experiment"

I was always left with the impression that the lesswrong community was secretly an apocalypse cult building the basilisk themselves. Most of their behavior makes sense in that light... :facepalm: It's no secret whatsoever that LW is broadly behind an effort to make a Friendly AI. Once you've done t...
by drachefly
Wed Nov 12, 2014 2:21 pm UTC
Forum: Science
Topic: Can protons be extracted from an acid solution?
Replies: 26
Views: 5575

Re: Can protons be extracted from an acid solution?

And here we see someone who doesn't know how lmgtfy is supposed to work. If someone didn't already know about the Niven technology, how are they supposed to google that for themselves? I suppose I was a little lmgtfy happy. a little like the explosion from only a cubic millimeter of water minus the...

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