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comment Quantum Mechanics: how exactly does “delta function normalization” work for eigenfunctions in 1-d free space case?
Ah, I see the main confusion going on here... the 1-d free particle wave-function isn't normalizable since it doesn't go to zero at infinity. Here might be a nice source to look at: physicspages.com/2012/09/11/…
2d
comment Quantum Mechanics: how exactly does “delta function normalization” work for eigenfunctions in 1-d free space case?
Yes, you are not really understanding what a dirac delta is. It isn't an infinity at zero, it is a distribution defined by its integral properties. So one the first integral expression of the final line is incorrect.
Apr
19
comment Would a world filled with water collapse?
@JohnRennie: Just a quick clarifying comment on word choice that you probably know. The object collapses into a black hole not when the radius "exceeds" the Schwarzschild radius, but when it LESS than that radius. You need to compress the object into that radius (for example, for the earth you need to squash it into about the size of a golf-ball).
Apr
14
accepted Pressures Necessary for Carbon Detonation
Apr
9
awarded  Yearling
Dec
13
awarded  Popular Question
Nov
10
comment Is a black hole's mass uniformly distributed?
There are many things wrong about this answer: 1) There exist stable orbits around black holes under a variety of conditions, just because you fall towards a black hole doesn't mean you will pass the event horizon. 2) If you mean "fall directly at the black hole," it is still incorrect as until you cross the event horizon you will still theoretically be able to accelerate away from the black hole and escape. 3) Since you are a 3d object you don't pass the event horizon instantly. 4) You don't really explain the actual answer of "NO hint of distribution of mass-energy inside the black hole"
Nov
10
comment How to push a ball out of tube without air compression or springs
Interesting problem, although artificial. Maybe if you create something that spins the pipe around at a given angular speed and then releases the ball? You would need to very precisely time the release of the ball though, which would probably require some electronic (i.e. metal) timer. See the "centrifugal" designs here: science.howstuffworks.com/transport/engines-equipment/…
Nov
5
comment Is it possible build a telescope on a field of mirrors?
It is certainly a cute idea! My hunch would be that it would be impossible to resolve an image, but it might be useful to take spectra of a very distance object... Like you point all the mirrors towards a single point in the distance and take the spectra of the reflected light. But, probably the accuracy you would need to focus on that point would be impossible to achieve as well...
Oct
27
accepted Power spectrum calculation in Weinberg's cosmology
Oct
27
revised Is it possible to look into the beginning of the Universe?
added 106 characters in body
Oct
9
awarded  Enlightened
Oct
9
awarded  Nice Answer
Jun
15
awarded  Nice Question
May
16
revised Relativistic rigid motion
added 1 character in body
May
5
awarded  Nice Answer
Apr
9
awarded  Yearling
Feb
23
comment The uncertainty principle and spin
Traditionally, the view has been that by observing the spin along one direction, you have collapsed the spin wave function and can no longer identify information about the other spin axis. It is analogous to not being able to know the position and momentum of a particle; the microsecond you observe position of the particle you lost all information about the momentum.
Feb
23
revised Why are heavy things harder to lift?
reformatted to standard G for gravitational constant as opposed to confusing gamma, fixed spelling
Feb
20
asked Power spectrum calculation in Weinberg's cosmology