If, theoretically, you were in an infinite sized room, and there was complete darkness. If you lit a candle, how far away would you have to be from this candle before you couldn't see it? |
- If, theoretically, you were in an infinite sized room, and there was complete darkness. If you lit a candle, how far away would you have to be from this candle before you couldn't see it?
- How do astronauts perform wet chemistry experiments in the microgravity?
- Why does it take some medications (such as antidepressants) up to two weeks to take effect, while with OTC stuff like tylenol it takes a few hours?
- How does the new 2 trillion upper limit of galaxies affect dark matter and the "missing mass" theory?
- How does file recovery software work?
- Is there a benefit to seeding an RNG with a large prime number?
- How do we create artificial elements heavier than uranium but cannot create hydrogen fusion?
- Why is there so much rainfall in East Asia, even though most of it is at the same latitudes as the Sahara desert?
- Is gravity the same throughout the earth?
- Can gyroscopes at the end of an axle or some other "no thrust" alternative be used to control the rate of precession of a big spinning wheel in space?
- How can the masses of the right and left-handed neutrinos be different?
- Could dark matter/energy be explained by countless black holes?
- What is the difference between measurements of cortical thickness, grey matter concentration and grey matter volume?
- Can you use an electric field to cause targeted opening of voltage-gated channels?
| Posted: 15 Oct 2016 01:27 PM PDT |
| How do astronauts perform wet chemistry experiments in the microgravity? Posted: 15 Oct 2016 10:49 AM PDT A titration in microgravity sounds very complicated, for example. [link] [comments]  |
| Posted: 15 Oct 2016 09:16 PM PDT |
| Posted: 15 Oct 2016 12:51 PM PDT This recent article in 'The Astrophysical Journal' presents that the upper limit of galaxies may approach 2 trillion. Being at least an order of magnitude higher than previous estimates, does this now offer an explanation as to the missing mass in the universe? Does it change the impact or amount of dark matter/energy that may exist, or is the observation of dark matter unaffected and simply the estimated total mass of the universe increases? [link] [comments]  |
| How does file recovery software work? Posted: 15 Oct 2016 02:25 PM PDT There's software that can recover deleted files even after emptying the recycle bin. How does this work? [link] [comments]  |
| Is there a benefit to seeding an RNG with a large prime number? Posted: 15 Oct 2016 12:01 PM PDT |
| How do we create artificial elements heavier than uranium but cannot create hydrogen fusion? Posted: 15 Oct 2016 12:39 PM PDT Asking off the basis that you would need to fuse or add more protons, neutrons and electrons to an atom to create heavier elements so why can we not do that with hydrogen? [link] [comments]  |
| Posted: 15 Oct 2016 04:24 PM PDT |
| Is gravity the same throughout the earth? Posted: 15 Oct 2016 08:51 AM PDT |
| Posted: 15 Oct 2016 11:57 AM PDT Elon Musk's recent presentation of SpaceX's proposed Mars architecture has got me wondering if his giant booster could be used to put a practical "wheel in the sky" space habitat in orbit around Earth. My goal is a fairly self sufficient community of a few thousand people in space: air / water / waste recycling, hydroponics / fish farm, classrooms, sick bay, shops, offices, entertainment, fabrication, labs. 15-17m diameter x 47m long cylindrical modules are joined by 7.5 degree mating adapters to form a 715 m wheel. Each of the modules has 5 decks that are about 2.5m tall. Artificial gravity is a necessity, long term bone density loss and other issues are killers. Carbon fiber cables join to a central hub like spokes. Other cables hold the hoop in compression (like the hoop around barrel stays) or spanning module-to-module along the inside. All this cabling keeps our wheel intact as it spins at 1 rpm, giving 0.8 g artificial gravity. The wheel is big enough that Coriolis effect won't make inhabitants nauseous. My ideal scenario is to launch each module, have tugs meet them and shepherd them into position. Solar and cosmic radiation shielding comes from the walls being filled with a fluid. The outer walls have two layers, and initially the walls are hollow and empty. After the wheel is assembled, the ITS tanker delivers a fluid that is pumped into the gap. My preferred orbit is a sun-synchronous circular orbit about 700 km and 98 degrees inclination and it would continuously track above the day-night terminator. (There are already several satellites that do this.) In that orbit, I would like the big wheel to precess exactly once a year so that one side of the wheel is continuously facing the sun and the other side always stares into cold dark space. This allows the wheel to have solar panels that are always gathering energy and radiators that are always dissipating excess heat. It also avoids issues that arise from cyclic hot-cold cycles, they would make sealing between modules more challenging and cause fatigue that reduces operating life. Last, it allows one side to have extra shielding for solar protons. I understand that galactic cosmic radiation is a huge issue, especially since the orbit goes above the poles. The issue is how to make the big wheel track the sun by precessing one turn a year. I did some math and came up with 192 newtons of force being applied to each end of a 200 m axle (one end's thrust point up, the other end down). There is no way to do that with thrusters, the mass of chemical fuel would be enormous. We have an awesome amount of continuous sunshine at our disposal, so a lot of electric power could be available. Is there another way to apply torgue to the big wheel's axle or change center of rotation or otherwise make the wheel precess? [link] [comments]  |
| How can the masses of the right and left-handed neutrinos be different? Posted: 15 Oct 2016 07:31 AM PDT If a left neutrino is emitted and starts travelling at some speed in a given direction, since it has mass surely I can pick a reference frame where it is travelling in the oposite direction. If that boost does not change the orientation of the spin, do I not end up with a right-handed neutrino in the new reference frame? If so, how can the masses be different? Is mass not Pmu .Pmu, which should be Lorentz invariant? Also, if the above were true, could we detect right handed neutrinos by having the emission source travel extremely fast with respect to the measuring apparatus? Thanks! [link] [comments]  |
| Could dark matter/energy be explained by countless black holes? Posted: 15 Oct 2016 07:37 PM PDT I was thinking about how dark matter and how gravity can bend light as seen in gravitational lensing. Since our only way of detecting things in the universe (other than through gravitiational waves) is by looking at the light waves that come from space, it seemed intuitive that all this unexplained mass and energy that we classify as dark matter could just simply be from the fact that the photons in those areas never reached earth for us to see. My "theory" for this is that super massive black holes, with strong enough gravitational pulls, intercept the photons that would have reached earth. If this is the case, it seems that depending on how close the wandering black hole is to us, it could block out more or less of the photons that would've reached earth. Thanks! :) [link] [comments]  |
| Posted: 15 Oct 2016 07:20 PM PDT I am reading some papers on the effects of meditation on the brain and I am curious what these different measures really mean in terms of what they tell us about the effects of meditation on the brain. Thank you! [link] [comments]  |
| Can you use an electric field to cause targeted opening of voltage-gated channels? Posted: 15 Oct 2016 08:24 AM PDT Just to build on the title... is it possible to create a local electric field which would cause (or sustain) an open state of voltage-gated channels within tissue? Or alternatively... Is it possible to depolarize a cell membrane on a tissue-specific basis? Or do membrane potentials of different cell types overlap in such a way that precisely opening one population of cells would be impossible? [link] [comments]  |
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