1,809 reputation
410
bio website
location Netherlands
age 40
visits member for 3 years, 8 months
seen 16 hours ago

16h
comment Is the frequency of light restricted?
"High frequency light" would be X-rays and gamma radiation. We can already produce that, the thing we can't do is aim it. And we're trying very hard to achieve that. Don't bother with weapons research, the chip business needs it now. ASML is fighting the problem that lenses don't work anymore at the extreme UV wavelengths.
Jul
21
answered How does radiation shielding using absorbing materials work?
Jul
14
comment Why do co-rotating vortices coalesce, but not counter-rotating ones?
Also, look at the area between the two vortices. In Mike's example, there's tremendous shear. The downward motion on the right happens very close to the upward motion on the left. That's not a stable situation. The two currents will interfere, slow each other, become turbulent, and as a result the air there becomes stationary - the core of the new single vortex. In the original question, the flow in the middle is unambiguously downwards and this is a stable pattern.
Jul
6
comment Units of a discrete Fourier transform
@Void: If you'd want to determine the potential energy in a volue, you'd integrate the potential energy density over that volume.
Jul
4
answered Units of a discrete Fourier transform
Jun
24
answered When recombination in PN junction occurs, which atom becomes an ion?
Jun
24
comment How to tell if the collision is elastic or inelastic?
I think you know how to calculate the velocity for a perfect inelastic collision. (I assume so because you say "new object", singular). For other inelastic collisions, the two objects do not fuse and resulting velocities are dependent on the fraction of energy converted to heat.
Jun
22
answered Why can't a gas be liquified by pressure above its critical temperature?
Jun
20
comment Why does a large train cause the ground to shake?
A person only has two legs. But an army marching is instructed to walk normally over bridges for the same reason, yes: the rhythm of marching can cause the same vibrations.
Jun
20
comment Do electrons have shape?
@brightmagus: Sorry, no, science does not define physical that way. Heck, since de Broglie we know that an electron is also a wave, which makes the entire notion of "volume" is literally fuzzy.
Jun
19
comment Do electrons have shape?
@bright: you claim that "something" must exist, and then assume "something" must be volume. That just doesn't follow. Particles have a set of properties, some of which can be null - but not all as that wouldn't be a particle. Your logic doesn't show why the volume property is special, and in particular it doesn't show why the volume property has to be non-null when other properties can be null.
Jun
19
answered Why does a large train cause the ground to shake?
Jun
19
comment Do electrons have shape?
-1. There are good reasons to assume shape matters. For instance, the trajectory of an electron tunneling through a crystal may very well depend on its orientation re. the attice. A shapeless electron can't have such an orientation.
Jun
19
comment Do electrons have shape?
@DavidRicherby: The two questions are connected. The shape of a cow is given by the probability of a point P+dP being inside the cow, given that a point P lies inside the cow. And the shape of that cow influences the chance of finding a cow at any point in the pasture (You won't find the spherical cow in the corner of the pasture ;) )
Jun
19
comment Do electrons have shape?
@brightmagus: "Something must be more than null". Clearly, the charge of an electron is more than null. That already satisfies the rule that something is more than null. Must all quantities of a particle be more than null? Clearly not, the charge of a neutron can be null. So why can't the volume of an electron be null? And a null volume has no shape.
Jun
11
comment Speed cannot be greater than speed of light. How about acceleration? Does it have limit?
John Rennie's example is clear enough: the acceleration doesn't change the energy since it's perpendicular to the velocity vector. (Assuming a circular orbit).
Jun
11
comment Why does a large train cause the ground to shake?
The track probably uses sleepers (timber or concrete) instead of having continuous support?
Jun
6
comment University of Delft results regarding quantum teleportation of information
The superluminal bit is still to be tested. But as the distance achieved is 10 nanoseconds, we can now accurately measure the actual time the teleportation takes.
Jun
6
comment Of all the electrical energy used in a home, is there any portion that won't eventually become thermal energy in the home?
@Klik: In the end, it will all become thermal energy. So the real question is just about the percentage in the home.
Jun
6
comment Of all the electrical energy used in a home, is there any portion that won't eventually become thermal energy in the home?
-1. The observations may be correct but this answer is about sociology, not physics.