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Everything posted by J.C.MacSwell
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Yeah, without this very unusual property of water the world as we know it would be very different.
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OK. I'll bite. How is it that something "new" and "fresh" has been held secret for "so long it makes you sick".
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I'll knead to add them to my latest French Bread recipe.
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All that said, there have been a few interesting threads in Speculations. There are also probably a few that could be good but unfortunately get overlooked due to the junk that gets deposited there and overall it is certainly worthwhile rather than just throw it all out entirely.
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Why does time tick at different rates at different locations?
J.C.MacSwell replied to Vay's topic in Relativity
Higher gravity, or equivalently greater acceleration. With lower gravity or less acceleration time elapses faster. -
Why does time tick at different rates at different locations?
J.C.MacSwell replied to Vay's topic in Relativity
Think of a light clock just outside the event horizon of a black hole positioned so that the light bounces radially. Obviously the "up tick" will ensure that this clock runs very slowly compared to a similar one at a safe distance. where gravity is stronger (or acceleration is greater) time runs slower. -
Everywhere the same red-shift, possible?
J.C.MacSwell replied to alpha2cen's topic in Astronomy and Cosmology
That would assume preferred directions in space, with redshift visible in two dimensions but not in the third, thickness, direction. Where is the evidence of that? -
A few thoughts on timeline & entropy
J.C.MacSwell replied to Djordje's topic in Astronomy and Cosmology
Not absolutely sure about the weak interaction as I know (am aware of) there is a symmetry violation with it, but I think it would have to be as well, assuming time run backwards would get you back to an earlier starting point. (quantum uncertainty aside) http://www.lbl.gov/abc/wallchart/chapters/05/2.html (Interesting Feynman quote about meeting an Alien) But in classical mechanics all forces stay the same. -
A few thoughts on timeline & entropy
J.C.MacSwell replied to Djordje's topic in Astronomy and Cosmology
It does under time reversal. Dissipated energy converges, glass fragments combine into a glass with the combined kinetic energy to leap, still against the force of gravity, to land on the table. If Gravity was repulsive under time reversal the glass (and table) would be heading for the moon, and if other attractive forces were reversed everything would blow apart. -
A few thoughts on timeline & entropy
J.C.MacSwell replied to Djordje's topic in Astronomy and Cosmology
Even in Newtonian mechanics the forces remain the same and do not reverse with time reversal. Attractive forces remain attractive, and repulsive forces remain repulsive. -
A few thoughts on timeline & entropy
J.C.MacSwell replied to Djordje's topic in Astronomy and Cosmology
Sorry. Bad joke.... 28 billion is twice 14 billion which is roughly the time from the apparent Big Bang. If your assumption is correct about expansion and entropy increasing being linked, then we could very well be in a contraction stage but not know it as our brains would be in reverse. -
A few thoughts on timeline & entropy
J.C.MacSwell replied to Djordje's topic in Astronomy and Cosmology
Didn't we have this discussion 28 billion years ago, except this time we are having it forwards?...or is it backward this time? -
Thanks... the angular momentum referred to is quantized and also non-classical, correct? In String theory it would be assumed to be in extra dimensions? Any room for the photon to be hiding in there? (I know the last answer is no, because that is not what we call a photon...but all the little quantized bits and pieces seem to be conserved)
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So the photon's energy and momentum is absorbed...what happens to it's spin??...is this absorbed as well?...I'm thinking this should be conserved as well...somehow...
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Silly question but would this be possible in zero gravity?
J.C.MacSwell replied to ForeverNoobie's topic in Physics
Well... I've certainly managed to fend off a 5 ton boat (and much larger in calm conditions), moving at slow speed, from a dock or wharf... It's all a matter of how hard you push, for how long, and how fast it is moving/converging. a=F/m -
Well, if they're not there now and neither is the former moon, what else can one conclude??
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Hardly makes it worth while.
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How do Photons exert Electrostatic forces ?
J.C.MacSwell replied to Widdekind's topic in Quantum Theory
from above: "explaining why they never venture far from the particles producing them" Doesn't that imply a distance limit to the Coulomb forces? And if they fizzle away exponentially in time, why is it an inverse square law? -
Doesn't the best theory we have as to how things all started violate conservation of energy in a pretty "blatant" manner?
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Only got that far, but that's an interesting way of looking at it. It probably falls outside the definition of "natural selection" (just a guess, as I'm not an expert) but in many ways it's the same thing.
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The impossible machine runs faster than the wind pushing it...
J.C.MacSwell replied to Externet's topic in Engineering
If the true wind disappears you have no energy source but your momentum (kinetic energy) relative to the ground. Since you still have drag your device will eventually come to rest. Also, you certainly can go upwind at faster than windspeed. (been there, done that, as has Sisyphus in iceboats...unless his iceboat was a real beater ) As for the bolded, the device would "know" it is moving over the ground, as the energy source it uses to maintain it's speed or accelerate is the kinetic energy of the wind relative to the ground, and the energy it expends in traction would be vehicle relative to ground. So it would "know" if it was true or apparent wind. -
The impossible machine runs faster than the wind pushing it...
J.C.MacSwell replied to Externet's topic in Engineering
The old "paired molecules splitting and meeting back together after traveling different paths" explanation leads to problems. It has erroneous assumptions leaving it only partially correct. Most sails can be made to work quite well. There really is no debate outside of how best to explain things. Newtonian explanations are correct if the right assumptions are in place. Bernoulli's Principle is based on certain idealized assumptions and is in agreement with and based on Newton's laws. -
The impossible machine runs faster than the wind pushing it...
J.C.MacSwell replied to Externet's topic in Engineering
Well, we know we have done it in iceboats...sailed with the downwind velocity vector greater than the wind velocity...and two iceboats on opposite tacks can maintain their combined c.g going straight downwind at greater than windspeed... Are the turbine blades accomplishing essentially the same thing? ' Have to think about it... Now this makes sense. The propeller must be variable pitch. It must be maintained by dynamic braking on the wheels, which drive the propeller which seemingly gathers energy...even though at windspeed the "relative to vehicle" energy source is the road, not the wind. The blades simply push with more net force than the force of the dynamic braking, using the energy of the wind relative to the road, even when the vehicle speed matches the wind and there is no available wind energy relative to the vehicle. Actually it wouldn't have to be variable pitch either, even at the start, though it would be more effective. Energy is a very relative thing. -
The impossible machine runs faster than the wind pushing it...
J.C.MacSwell replied to Externet's topic in Engineering
No. I meant upwind. Is there something unique about sailboats? I have an iceboat, fairly common design, that will go faster than the windspeed. In light air it will go upwind much faster than downwind. While it will not go directly upwind, it gets there by tacking, and the speed made good to windward is greater than the true windspeed in many conditions. I can't see how you could maintain downwind faster than the wind though. -
The impossible machine runs faster than the wind pushing it...
J.C.MacSwell replied to Externet's topic in Engineering
I don't see anything controversial. It has to be fairly efficient to go upwind faster than the wind, but it certainly can be done. At some point the drag increases too fast for the increase in available wind energy, but this does not necessarily happen at the same speed (while opposite direction) as the wind. "Impossible" would be having it work in no wind, even after pushing it to get started. Also, a flat plate can generate lift, though it is not very efficient.