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Apr
13
comment Can you heat something in AL foil using IR?
@RickPH If you didn't already notice, Aluminium is a metal. A metal reflects most EM radiation frequencies well because of the wide conduction band they support. In short, THERE IS NO SWEET SPOT.
Apr
13
comment Can you heat something in AL foil using IR?
In fact Aluminium foil is often used to do the opposite of what you are asking OP.
Apr
3
comment Is speed of propeller-driven airplane limited by the speed of sound?
@tpg2114 I disagree with you on one significant point. You would see loss of lift not just at the tips, but the entire blade. Loss of lift STARTS at the tips (since they are moving the fastest). But by the time you are in supersonic airflow, all of the blade is moving through the air faster than the speed of sound (even if the blades stopped rotating). However, supersonic blades do still generate lift, as the Tupolev Tu-95 demonstrates.
Mar
24
answered Can an electric current's magnetic field be represented by a magnet/magnets?
Mar
13
comment Is it possible to sail “close hauled” with a solar sailship?
@jameslarge hence when I am teaching I use the term "lateral resistance" which I believe is the RYA term, as opposed to "keel action" which could also refer to the righting action of the weight. Oh forgot to say, I'm a sailing instructor as well as a master in physics.
Mar
12
comment Is it possible to sail “close hauled” with a solar sailship?
@jameslarge a keel in sailing parlance is a weighted foil under the boat. Even if you extend it to non weighted, I am a board sailor... We definitely don't have a keel, nor do kiteboards.
Mar
12
comment Is it possible to sail “close hauled” with a solar sailship?
Minor correction, not all sailing boats have keels (for example cats and dinghies). The interaction is called "lateral resistance".
Mar
11
comment Is there an infinite amount of wavelengths of light? Is the EM spectrum continuous?
@MSalters it merely means that there is a countable number of inertial frames. If this were the case, it would imply that there were a countable number of energy levels/momenta (for inertial frames), which would certainly produce a self consistent set of rules. As a countable number of energy level/momenta would give rise to a countable number of wavelengths. I suspect we want a QFT expert to answer this one without handwavey arguments.
Mar
9
comment Does coffee cool faster than tap water?
@VolkerSiegel assuming that the particulates thermalise in a time that is insignificant to the bulk cooling of the water.
Feb
25
comment Is there a minimum energy content of information, other than 0 Joules?
en.wikipedia.org/wiki/…
Feb
24
comment Where does information go if thermodynamic death?
There is no law of thermodynamics on dissipation of energy. There are however laws to that effect on entropy/information and separately with heat...which is basically energy which has entropy. The point is a classical black hole does not exist. Its wrong. In fact people knew it was "wrong".
Feb
24
comment Where does information go if thermodynamic death?
@JohnRennie okay..black hole evaporation. There was a very famous bet between a Steven Hawking and Kip Thorn on this very matter. The result was Kip won, and information does indeed leak out of a black hole. Also information loss IS entropy increasing.
Feb
24
comment Where does information go if thermodynamic death?
The point is that each reversible reaction yields more information. That information is the step to reverse that reaction. Thus as long as you keep all the information you can recombine it in reverse with the system to yield the original state. Its a bit of a cop out...the reaction is reversible until you lose the thing to reverse it...
Feb
24
comment Where does information go if thermodynamic death?
@lemon not with infinite (or enough) informational storage. The difference is important in a question on entropy and information theory.
Feb
24
comment Where does information go if thermodynamic death?
Information IS lost. That is how we know we are going forward in time. Entropy increases. For example.. Your egg. How do you de-evolve the system to give you the height at which it fell? What if the egg reached terminal velocity during its decent? Your answer is patently false.
Feb
24
comment Where does information go if thermodynamic death?
@lemon I disagree with your analysis. The point of Maxwell's Daemon is that it can reverse a system, simply by opening and closing a door. The informational analysis of Maxwell's Daemon is that as the system evolves, more information needs to be stored, until eventually, Maxwell's Daemon must delete information (assuming finite information storage). The process of informational deletion is synonymous to increase of entropy and the arrow of time.
Feb
22
comment Why would a sweeping LIDAR or RADAR beam not produce an artificial Doppler shift?
@dmckee nor can individual components of the beam affect other parts of the beam (a simple argument on SR space time diagram can show this).
Feb
22
comment What are the main issues that are preventing a human mission to Mars?
@dmckee Don't migrate it. This is a dup in SX. space.stackexchange.com/q/4
Feb
22
comment Why would a sweeping LIDAR or RADAR beam not produce an artificial Doppler shift?
The sweeping beam isn't real. For the same reason that the beam can sweep an arc that "moves faster than the speed of light".
Feb
16
comment Why does it take so long to get to the ISS?
@DewiMorgan technically what you are talking about is orbital insertion. Also, that would be true only if we ignore the planet's spin...>_<