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    Inertial mass, gravitational mass, and the Higgs

    In other words, the higgs mechanism contributes directly to the stress-energy of the particle - did I understand correctly? If so, allow me to refine my understanding with another question. In the higgs model, does the contribution to the inertial mass and the contribution to the...
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    Inertial mass, gravitational mass, and the Higgs

    If we explain the origin of inertial mass with the Higgs mechanism, how do we explain the origin of gravitational mass? In other words, how does the Higgs mechanism contribute to the gravitational field of a particle? (Note: the closest thread I've found to this is...
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    Future construction - a theoretical estimate?

    Since ancient times our species has always looked toward the sky. For that reason I find it hard to believe we will cease our attempts to build ever higher. However, we may do both. In any case, this is a philosophical discussion which is not the concern of this thread. If you wish to pursue it...
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    Future construction - a theoretical estimate?

    Hmm... forgot about bedrock.. I suppose with a deep enough foundation that can be resolved. Of course, one would also need the technology to build that deep. and I guess you'd have to count the foundation depth as part of the total structure height as far as structural integrity is concerned. So...
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    Future construction - a theoretical estimate?

    Yes, I've thought of the space elevator as well. But I would like to focus more on the skyscraper problem (sorry if it wasn't highlighted enough). I would think that the problems for a skyscraper would be different, since it is not suspended and hence doesn't gain as much from centrifugal...
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    Future construction - a theoretical estimate?

    Suppose we had the technology to produce artificial diamond beams and carbon nanotube rope cheaply enough to use in large quantities. If we use the diamond for compressive load, and the CNT ropes for tensile load, how tall a skyscraper could we build using these materials, in theory? Is there...
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    Matter-antimatter imbalance - how do we know?

    Yes, if the matter and antimatter were close together, they would sooner or later annihilate, and we would expect to see the associated energy release. But would it not be reasonable to assume that where such events could occur, they have already occurred, for the most part, a long time ago...
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    Matter-antimatter imbalance - how do we know?

    In my thread regarding the telescopic detection of antimatter, it was concluded that we cannot discern anti-matter from matter when observing it via telescope. As a follow-up, I have another question - or rather a few tightly connected questions: If we cannot tell the difference when looking at...
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    Can we tell apart antimatter from matter?

    Hello, assuming we can detect antimatter with some telescopic technique just like we can detect matter, is there any way to tell them apart? How would this be done?
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    Hypersonic drag - spherical vs pointed nose

    This is a hypothetical question that I am curious about.. Suppose we are trying to design a projectile that is intended to travel at high hypersonic velocities, on the order of mach 10 or 20, through air (you can assume sea-level density for argument's sake). Would an ideally sharp round...
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    Exothermic reactions that release hydrogen?

    Hello, I was wondering if there are any exothermic (or otherwise spontaneous) chemical reactions that release hydrogen, in which the reagents and products aren't strongly hazardous? I know of the reaction of alkali metals with water, but these produce strong alkaline solutions.. Perhaps one...
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    Misc. Double slit - do it yourself?

    In hebrew there is a separate word for the part where the wave goes around an obstacle, and another word for the part where two waves combine and either add up or cancel each other. When I say "diffraction", I mean the former (going around obstacles), and when I say "interference" I mean the...
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    Misc. Double slit - do it yourself?

    There's also a difference between monochromacity and coherence. Monochromacity is when the light is all the same wavelength. Coherence is when it is all in the same phase. A laser has both of these qualites, whereas typical white light (e.g. from a lightbulb) has neither. And when I said one...
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    Misc. Double slit - do it yourself?

    Yea, you may be able to see some diffraction (as in light going around your fingers), but if I'm not mistaken you won't see any interference (as in light adding up constructively and destructively to form those familiar patterns). AFAIK you'll need a coherent beam such as a laser to see the...
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    Misc. Double slit - do it yourself?

    Ok, thanks for the suggestions - keep 'em coming. :smile: Btw, anyone tried to fill the area between the slits and wall with steam to see the diffraction pattern form along the way? And just a safety note for that - the scattered light would be weak enough to be harmless, right? Or would I need...
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    Misc. Double slit - do it yourself?

    Hello, is it possible to reproduce the double slit experiment at home with some easily obtainable equipment? I was thinking of using one of those laser pointers. Though I'm not sure how to make the slits - would cutting a pair of close lines in a piece of plastic with a sharp knife be good...
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    High Temperature Polymers?

    Yes. Thanks for the link. :smile:
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    High Temperature Polymers?

    Hello, could anyone point me to some resources where I can find information about high-temperature polymers? In particular, I am interested in the theoretical aspects of typical structures and how it enables the polymers' thermal properties and possibly other properties. Processing methodology...
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    Offcentre thrust, spinning spaceship

    True, but the point is that the centrifugal force would resist that bending. Because the moment the tether bends a bit, the centrifugal force is no longer completely aligned with the tether, so you get a component that acts to straighten the tether back. Not to mention that with the centifugal...
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    Lense flare / halo

    ok, so if I neglect the lense distortions, and assume a vacuum (hence no scattering), then I should see no halo? Just the bright surface of the light itself?
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    Lense flare / halo

    I was wondering - if I were to photograph (or look at) a bright source of light in full vaccum, would I see a halo around the light source, or any other lense flares? If so, does it form purely due to the lense optics, or are there some other contributing effects?
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    Offcentre thrust, spinning spaceship

    Assuming he starts up the rotation before he fires the engine, the centifugal force would keep the tether rigid even if it is flexible by default. And then when he does fire the engine, the thrust should distribute evenly around the center of rotation, giving a net forward thrust. Admittedly...
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    Game Physics

    Yes, this is correct. First you find all the forces, then you convert that to accelerations, then you intergrate to find the velocities, and finally the positions of the objects. Though iirc, the more advanced physics engines work with momentum (and perhaps some other quantity) instead of...
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    Wave-particle duality

    I'm not an expert, so take this with a grain of salt, but my understanding is that photons/electrons/etc are neither particles nor waves, but rather some other form of entity, which we do not fully understand, but which has the characteristics of both. The wave model and the particle model are...
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    Confused about antimatter and matter

    That was my first thought too, but according to http://en.wikipedia.org/wiki/Antiparticle the spin is the same: Plus, if memory serves, it was some more exotic property (or seemed so to me when I read about it somewhere a long time ago), even less well known than spin. Maybe baryon number or...
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    String threory assumptions about spacetime

    I took the quote from http://en.wikipedia.org/wiki/Quantum_gravity. I know that there may be errors in wikipedia, but I found this to usually be a reliable source. In any case, the full quote reads: It seems the starting point was a QT in fixed Minkowski spacetime, which they expanded by...
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    Confused about antimatter and matter

    IIRC, there is another property that is different, besides charge, but this difference doesn't usually receive much attention, presumably because the property is not well known to the general public.. Unforetunately, I don't remember what that property was. Anyone cares to freshen my memory -...
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    String threory assumptions about spacetime

    I just read that string theory "started out as a generalization of quantum field theory where instead of point particles, string-like objects propagate in a fixed spacetime background". Is this true? And if so, did anyone try to do the same with a curved spacetime? What did they get? Or perhaps...
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