Can a perpetual motion machine be built in space?
413533
Props to mathematician.  To expand, a "machine" must transform energy in some way.  The second law of thermodynamics describes that any time energy is transformed, entropy is created.  Whenever entropy is created, the "machine" must expel some energy in order to expel the entropy that has been created (if it doesn't expel the entropy, the machine doesn't run).  So every time a machine does something, it MUST lose some energy, and it cannot run forever.
418445
Are you referring to the Swiss perpetual motion machine?\n\nIf so, probably because no one has been able to duplicate the results at this point.
1018473
Absolutely no condecention was stated or intended Elmbvann.  Unfortunately, you can not disclose your idea here for a meaningful evaluation without placing it in the public domain.   I understand that the US Patent Office will not accept applications for perpetual motion machines (because none have been shown to be scientifically feasible).  I do not and can not judge your idea.  Perhaps it has merit.  But again it can not defy science and physical laws.  It can not create energy but it can certainly collect, concentrate and utilize existing energy much as a lens can be used to burn a leaf.  I never worry about "best answer" since I hope that most even all answers will help the questioner.  When someone asks a good question I often do a little research because I want to know the answer too.  Best of luck with your idea.
183248
You can use solar energy to evaporate water anywhere where you  can keep water in liquid state. Rather than constructing a steam engine, why not build stirling motors using any available gas, and avoid the narrow climate range? As with the steam engine, the Stirling would require a station in the cycle where the gas is heated and one where the heat of the gas is transferred to a colder reservoir.\n\nIn both cases you get mechanical energy which then can be transformed into whatever energy you might need. For getting electricity, direct transformation of sunlight into electricity in solar cells might be a more effective way.
850701
Cold fusion : http://arstechnica.com/journals/science.ars/2006/3/8/3099\n\nPerpetual motion:\nhttp://patentpending.blogs.com/patent_pending_blog/2004/12/perpetual_motio.html\n\nMale performance enhancers:\nhttp://www.themediadesk.com/files/enhancements.htm
1148300
All space garbage should be recycled and composted into an ecosystem. Thats the complicated set of chemistry questions that goes wtih that particular problem.\n\nUsing large enough diameters and centripetal force we can generate strong enough and stable enough pseudo\ngravity to compensate for that problem. A chemical problem with a civil engineering fix.
475694
A Dyson Sphere is basically a globe that you would build around a sun.  All of the energy put out by the sun would fall on the inside of the Sphere.  Thus (I love saying that word) you would control all the energy of the sun.\nThe problems would be having enough materials to make it.  Using all of the metals in our solar system, a Dyson Sphere placed near the orbit of the earth would only be a few molecules thick... thus (he he he) very fragile.\nAlso, you wouldn't be able to approach the sphere safely from the outside because there would be very little light on the outside.\nAlso, where would you stand as you dismantled our solar system... a bit of a problem.\nIn the Larry Niven book, "Ring World" some of these problems are solved, because the created a 'dyson ring' instead of a sphere.  Check it out!
37315
yes, a perpetual motion machine is one that requires not external energy input in order to keep working. The laws that a perpetual motion machine (PMM) would violate would be either the 1st or 2nd law of thermodynamics.\n\n1st law: the conservation of energy -> energy that goes into a system = energy that goes out. Energy cannot be created or destroyed. Has to go somewhere. A machine that keeps producing energy as work without energy input would violate this law.\n\n2nd law: I can't think of how the examples I've seen of perpetual motion violate the 2nd law (the total entropy of any isolated thermodynamic system tends to increase over time, approaching a maximum value), but wikipedia states that some proposed PMMs are ok with the first law and would violate the second.\n\nWikipedia has this to say about almost perfect PMMS:\n\n"By minimizing friction and other causes of dissipation, it is possible to produce a good approximation to a perpetual motion machine of the second kind. Planetary systems (such as the earth and moon) could be considered an example. Planets, moons, and stars spin without any fuel, batteries, muscle, cost, or other limited power. Planets don't rotate forever however - the rotation ends when the planet dies. (Energy in such system are dissipated via tidal effects and presumably also very slowly via gravitational waves.)\n\nIn an otherwise completely empty Newtonian universe, a single particle could travel for ever at constant velocity with no violation of the laws of physics -- though of course no energy could be extracted from it without slowing it down. For example, an electron can spin around a nucleus in an atom of matter for thousands of years until it degrades or is knocked out of orbit. A further example is light bouncing between two parallel mirrors, assuming those mirrors to be perfectly reflective (so that no light is transmitted or absorbed), perfectly parallel (so that it really does bounce for ever), and perfectly smooth (so that it isn't scattered). Making the mirrors into a closed box eliminates the need for them to be perfectly smooth or perfectly parallel, but not the need for perfect reflection. Perfectly reflective mirrors do not exist."\n\nAlways had wondered why light bouncing between mirrors would not constitute a PMM, now I know :)\n\nThe only diagram I remember of as a PMM from my readings as a youth was a Bhaskara's wheel, which I found a description on wikipedia, and a link to an image in the sources:\n\n"unbalanced moving parts arranged around a wheel fall, releasing energy which enables the wheel to turn; as it does so, the moving parts are returned to their original positions. The unbalanced parts may be hammers on pivoted arms, or rolling balls, or globs of mercury in tubes; the principle is the same."\n\nThe attempt to create a PMM has performed over the years, and you can find a history of PMMs using the second link.\n\nAbout the answer that spinning electrons constitute a PMM: see the above quote from Wikipedia - it seems that they will not spin forever.
73989
Newton tackled this question in his formulation of his first law of motion,saying that a body would moves continuouly unless slowed down by friction. In our local space machines move and because of fiction,will at some point stop.\n\nIn Universal space a celestial body will follow the same law\nand would continue its motion ;however, if there is friction in space and the it will eventually slow down.\n\nTherefore, according to Newton"s first law ,the Universe as a machine will eventually stop. We are forced to conclude that perpetual motion cannot be maintained.\n\nWe have to assume that Newtons is correct and this is what the scientist believe. However,no complete explanation in the main stream of science about the  exact cause of motion has been given.Human perception of the universe has its limits.
218567
There is no "close." You either have perpetual motion or you don't. Because any device you can come up with will have energy loss due to heat lost by the work done, you can never have a physical device that will keep going without additional energy. There is a theoretical particle that can never go slower than the speed of light, which I guess would be a form of perpetual motion, but it is not man-made.
1179954
Yes, it could be done, but you would need a very large field. Even so, scientists have allready created super electromagnets to levitate stuff.
249772
Well first use have to design it. The design dictates the assembly. The first design thats come to my mind is a catameran configuration. It has low drag and a large surface area on the top to put the solar cells. BTW large solar cells = $$$. Anyway an electric trolling motor would probably be the easiest and best bet to convert the electricty generated by the cells to power/boat movement.
836797
If you are asking about anti-gravity cos you've seen an episode of star trek who's anti gravity engines run on anti matter then the answer is NO.\nI saw a program on the Sci-fi channel a few years back and an American guy had made a circular pad with about 1 metre radius which once turned on you could put any thing on it and it would just float in mid air, this guy just built it at his own leisure.\n\nThe question of moving at light speed is impossible for nearly anything except light, scientist now believe that it would be more feasible to bend space around an object so it would instantaneously leave one point in space and reappear in another
834169
An idea for a nanobot or robot that would be bad news for the world, depending what it could use as building material.\n\nWe really don't want machines replicating in a geometric progression... which they probably couldn't anyway.\n\nIn Sci-Fi they seed places with these nanobots and when activated they build combat equipment after making enough of themselves. That's just fiction though and lets hope it stays that way.
996396
Yes, but it would be expensive to build the equipment and incredibly dangerous - imagine if the laser was hit by a small bit of space debris and the laser light moved - it would be like dropping a fire-bomb.  \n\nFar better to harvest the natural sunlight when it reaches the earth!
199267
well, i don't see why not.  if you made the thrusters such that the thrust was directed tangentially, that would cause the saucer to spin in a circle.  if you then added some kind of protruding airfoils (like helicopter blades) these would provide lift, but in the upward (axial) direction.  \n\nhowever helicopters can fly forwards and backwards by essentially tilting their rotors;  i don't see any reason why that wouldn't work in this case as well.
20369
No. The rotation continues simply because there is nothing to stop it in space.  A free object will continue to rotate along the same axis unless you apply a force to it.