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location Netherlands
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visits member for 3 years, 9 months
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Aug
28
comment Is the Big Bang defined as before or after Inflation?
TBH it's entirely reasonable to use the term in astrophysical contexts such as "One billion years after the Big Bang ...". The term is only troublesome if you need to distinguish the phases of the early universe.
Aug
15
comment Does large acceleration have to cause damage to the human body?
@Trimok: I'm fairly certain that the parachute jumper is accelerating with 1g when he leaves the plane, unli air resistance catches up (at which point it's no longer a free fall, strictly speaking)
Aug
15
comment Does large acceleration have to cause damage to the human body?
@MariusMatutiae: You can't really switch on and off gravity, but let's assume for a moment that you can: when turned on, it would accelerate your internal organs at the same speed as your bones.
Aug
14
comment Does large acceleration have to cause damage to the human body?
A lift moving upwards does not exert a force uniformly on your body. In fact, the force will act exclusively on your shoes/feet.
Aug
14
comment Does large acceleration have to cause damage to the human body?
@Bernhard: That's because there are mechanical (external) forces acting on them. There's pressure on your skin keeping your feet up, and by extension your bones up, but not your blood. Gravity on the other hand attracts the blood just as much as any other part of your body.
Aug
14
comment Does large acceleration have to cause damage to the human body?
Same thing as hitting the tree: an external force, in particular electro-magnetic (atoms in your chair repulsing atoms in your body). For the human body, the only feasible uniform force is gravity, and as noted before in freefall your organs don't get squished.
Aug
14
comment A common definition of a scalar
@ACuriousMind: I know, but that requires an unusual system with less available states at higher energies. I'm not familiar with any macroscopic system in which that's the case, so I feel that "obscure" is an appropriate label. (And the Casimir effect produces a negative pressure)
Aug
14
comment If I charge a battery using a much higher amperage, can it explode?
And of that 1500W input, of course quite a few W will still be used to charge the battery. It's the excess power which generates the hydrogen gas and heat.
Aug
14
comment A common definition of a scalar
Negative pressure and negative temperature are already borderline obscure (Temperatures are of course properly expressed in Kelvin, starting at 0K).
Aug
14
comment Is Gravity related to velocity?
All objects move at high speed, in some reference frame.
Aug
14
answered Speed of light versus pull of gravity - Is $c$ really the limit?
Aug
14
comment Does large acceleration have to cause damage to the human body?
You keep missing the strong force which affected a body uniformly. The tree is anything but a uniform force.
Aug
14
answered Does large acceleration have to cause damage to the human body?
Aug
14
comment Does large acceleration have to cause damage to the human body?
@MariusMatutiae: But that are external forces which do not affect the body uniformly. Parachuters experience 1G acceleration from gravity in free fall, which is an example of the kind of uniform force that's harmless.
Aug
11
comment Is interstellar flight possible in near future in a way that would keep our civilization alive?
All your issues basically boil down to "it will have to be one huge ship", but that is not a science problem. It's not really an engineering problem, even, but a financial one. Gravity is fixable by spinning the living compartments, solar radiation versus meteorites just requires a big shield which is moved to the front somewhere near Mars, etc.
Aug
6
comment Since cables carry electricity moving at the speed of light, why aren't computer networks much faster?
@rob: No, it doesn't mean that. Clock delays are very predictable, and CPU's don't change shape. If you're 3 mm from the clock input pin, you know that the clock is delayed by 10 ps. What it does mean is that you can't assume that the entire CPU settles in a given state near the end of each clock period. Different parts of the chip have different (and overlapping) clock periods. That's actually an advantage as large parts of a CPU are cache nowadays. There's a certain logic in running the cache at half a period offset from the CPU clock.
Aug
6
comment Will the CMB ever stop shining?
The CMB is a finite amount of photons. Huge, but finite. If there's no big crunch, those photons will become rarer and rarer.
Aug
5
comment How to generate Red light from a Blue-Dominated Spectrum
LED is pretty efficient but still they'll be fairly hot locally - LED's are also small. I.e. you'd have an issue if your houseflies are attracted to IR.
Aug
1
awarded  Nice Answer
Jul
31
comment Is it possible to shield a camera so as to record from the inside of a running microwave oven?
I suppose you could put an ITO (Indium Tin Oxide) filter before the front lens, and ground the lens barrel. But that's somewhat risky.