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location Melbourne, Australia
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visits member for 3 years, 8 months
seen Oct 12 at 13:48

Sep
23
awarded  Commentator
Sep
23
comment Is it possible to create artificial gravity by magnetizing iron in the blood stream?
"For a human ... you will need a field 5 times as intense" That is incorrect. Perhaps you are thinking of the case where you have two objects of different mass but the same charge. But in this case the "charge" is proportional to the mass (assuming frog and human have very similar magnetic properties). Another way of looking at it is that a human is composed of many frog-sized pieces which should all accelerate as a frog would. It's slightly complicated by the fact that the field necessarily varies along the vertical axis, but assuming the same gradient, the average field will be the same.
Aug
23
comment Is it possible to avoid the radiation that caused the American flag turned into white on the Moon?
With no wind to speak of on the moon, a normal flag would just hang limply. The aluminium was probably to give them some stiffness.
Aug
13
comment What is the next step beyond quantum computation?
Your oracle machine with finite memory, and therefore a finite number of states, will not work. After a finite number of computational steps (less than or equal to its number of states) it will enter a state it has previously been in, and from then on repeat the cycle that led to that state.
Apr
13
awarded  Nice Question
Apr
2
comment Why Do Sausages Always Split Lengthwise?
The cylinder is not assumed infinite. Fluid pressure always acts orthogonally to a surface. A cylinder's side is parallel to its axis so doesn't contribute to axial stress. Only the ends can do that, and an infinite cylinder doesn't have ends.
Mar
1
awarded  Notable Question
Sep
19
awarded  Popular Question
Aug
16
awarded  Nice Question
Feb
28
awarded  Popular Question
Feb
20
answered How much better is salt water at letting through microwaves than pure water?
Feb
8
awarded  Yearling
Jan
3
comment If the ground states of interacting QFTs are so complicated, how did Nature find them?
@Scott Aaronson: obviously they don't do that because they have little to gain by it and everything to lose if mistaken, not to mention that the stunt would prove nothing to the scientific community, even if they were seen to survive against extreme odds. (the suicider gets to condition on remaining alive, but observers just see the expected outcome probabilities. So to an observer they were just lucky if they survive.)
Jan
3
comment If the ground states of interacting QFTs are so complicated, how did Nature find them?
@Scott Aaronson: I am not a physicist but my impression is that we don't need to worry about a possible false vacuum if the many-worlds interpretation is correct. Since we can never observe the vacuum collapsing, it will seem to never do so. Like quantum immortality, but with everyone in the same boat. It actually might be good evidence in favor of MWI if some theoretical argument showed that the vacuum was false.
Oct
11
comment Are black holes really that special?
"string theory ... spreads out the mass of an elementary particle along an extended object, so there isn't necessarily a high enough density to be a black hole" - I thought strings were 1-dimensional. Wouldn't you need to spread out in 3 dimensions to avoid infinite density?
Oct
8
comment Is it safe to observe the sun through binoculars with welding glass in front?
"If focused sunlight hits your eye, you will lose vision" - I think you're wrong about that. The brightness of the image of a point source is proportional to aperture or lens diameter, but an extended source behaves differently. The binoculars will increase the apparent size of the sun but not its brightness (per unit area). It would be no worse than glancing at the sun unaided and blinking, except the afterimage would be larger. (There's a limit to the brightness of a focused image, but when I try to google it, I only get results for diffraction limit)
Sep
15
awarded  Teacher
Sep
15
answered Is “Causality” the equivalent of a claim that the future is predictable based on the present and the past?
Jul
8
answered Simple Experiment to Demonstrate Special Relativity
Jul
6
asked Is the Higgs mechanism a fundamental interaction?