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 Yearling
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Apr
5
comment Gravitational waves frequency
@tfb figure 3 in that paper shows sensitivity in the 20-2000Hz range. The Einstein @ Home distributed computing program has searched that entire range for CW signals (from pulsar spin down) in data collected from the previous generation instruments; and is currently doing an initial search of the 20-100Hz range in data from ALIGO.
Mar
31
comment What leads to the existence of critical temperature?
@cst1992 or at your neighborhood dry cleaners.
Mar
31
comment Why is the cut off mass for massive stars 8 solar masses? Why can't it be 10-11 solar masses or so?
I hadn't heard of Oxygen/Neon dwarfs before. Do we know if the supernovas they produce look the same as more conventional Carbon/Oxygen ones?
Mar
22
comment The LIGO Gravitational Wave Detection: have deep-mantle earthquakes been ruled out?
@Lacklub the LIGO detection was many orders of magnitude smaller than what a conventional seismometer could measure. The previous generation of LIGO wasn't able to collect good data at the Louisiana site during the day due to noise from logging trucks in the surrounding forest. I suspect anything large enough to register on conventional seismometers would end up knocking the LIGO interferometer out until it passed.
Mar
18
comment Help! An 8 year old asked me how to build a nuclear power plant
@RedGrittyBrick gas centrifuges are the best method for enriching it; but the Manhattan project also put two other methods other methods into production during WW2: Electromagnetic separation via cyclotrons, and gaseous thermal diffusion although IIRC the amount of time the cascades for the latter needed to reach equilibrium was long enough that it was only used to produce moderately enriched uranium as an input material for the other processes.
Mar
18
comment Help! An 8 year old asked me how to build a nuclear power plant
@Nelson not quite this explanation, but yes Randal has a reactor in his book. You can see his explanation if you go to Amazon and use the look inside option (link above the book cover on the left side of the page); it's book page 3 (page 6 counting the un-numbered pages Amazon also shows).
Mar
11
comment How to calculate the force of gravity that wants to collapse a star?
Am I not thinking things through completely; but since a non-variable star is radiating energy at the same rate that countering collapse is requiring fusion to produce it can't you derive the force of gravity from its luminosity?
Jan
24
revised XP Decay mode of radioactive nucleus
fixed typos
Dec
19
awarded  Yearling
Dec
14
comment What would happen if the Earth was in a polar orbit around the sun?
Would rotating the Earths orbital plane affect perturbations from the rest of the planets to a significant amount?
Nov
19
comment Could we launch a missile from a planet with the mass of Jupiter?
@WetSavannaAnimalakaRodVance Hal Clements Mesklin (Mission of Gravity, Whirligig World, Heavy Planet) with conditions of several hundred g's at the poles would be a better SFnal reference.
Sep
18
comment How far out from the Sun is visible light still sufficient to read a book?
@Jitter Excluding a few comets, the dwarf planet Eris is the most distance known object in the solar system at 96 AU.
Sep
16
comment When I boil a kettle, what stops all the water from turning (exploding!) in to steam in one go once it reaches 100°C?
If the sort of accident you're describing in the last paragraph does largely empty the cup/etc; it's because bubbles formed so rapidly that they expelled a majority of the water the container in liquid form.
Mar
23
comment What if you opened a door in a spaceship without a spacesuit?
It's worth noting that the calculation in that answer for the force of outrushing air used a 20m^3 volume. That's much larger than a plausible personnel airlock would be.
Jan
18
comment How bright is a 150 W incandescent light bulb?
150W equivalent bulbs on amazon.co.uk. In the US higher wattage CFLs are also generally available in larger home improvement stores.
Jan
18
comment How bright is a 150 W incandescent light bulb?
@ColonelPanic you need to shop around more. Amazon has CFLs in the 2600-2800 lumen range; most of them run ~40W though. The potential gotcha is that they're noticeably larger than a standard incandescent bulb; and may not fit in fixtures that were designed to be barely big enough for a standard size incandescent. I believe the size constraint was why the US ban on incandescent bulbs stopped at the 100W size.
Jan
8
comment Why are grams usually only expressed as milligrams, grams or kilograms?
A dozen years ago my undergrad astrophysics classes all used cgs units as well.
Dec
19
revised Does gravity travel at the speed of light?
Updated date; schedule appears to've slipped slightly since my original post.
Dec
19
awarded  Yearling
Oct
25
awarded  Nice Answer