SteveZilla Posted April 22, 2012 Report Share Posted April 22, 2012 Re: More space news! for a gas to collapse' date=' there has to be a reduction of velocity of the particles that make up the gas. A normal gas can slow down via collision of the individual particles. Dark matter cannot collide with itself, so no collapse happens.[/quote'] But who says that dark matter behaves like a normal matter gas? Quote Link to comment Share on other sites More sharing options...
dmjalund Posted April 22, 2012 Report Share Posted April 22, 2012 Re: More space news! But who says that dark matter behaves like a normal matter gas?It is supposed to consist of particles with momentum, That is enough for my argument to be valid. Quote Link to comment Share on other sites More sharing options...
Christopher Posted April 22, 2012 Report Share Posted April 22, 2012 Re: More space news! But who says that dark matter behaves like a normal matter gas? Dark Mater is still an unprooven Theory. The point in that experiment was to find proof, but it failed. Our current theory say it does not collide. Because then it would form Chunks/Gravity anomalies that we can see and would not help in letting the galaxies rotate as they do. Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted April 22, 2012 Report Share Posted April 22, 2012 Re: More space news! Hey, does anyone know how to compute the Karman Line for other planets? Quote Link to comment Share on other sites More sharing options...
Christopher Posted April 22, 2012 Report Share Posted April 22, 2012 Re: More space news! Hey' date=' does anyone know how to compute the Karman Line for other planets?[/quote'] From Wikipedia i Have: "He first calculated that around this altitude the Earth's atmosphere becomes too thin for aeronautical purposes (because any vehicle at this altitude would have to travel faster than orbital velocity in order to derive sufficient aerodynamic lift from the atmosphere to support itself)." Propably one of the mayor factors is atmosphere density. And Atmosphere composition. Quote Link to comment Share on other sites More sharing options...
Christopher Posted April 22, 2012 Report Share Posted April 22, 2012 Re: More space news! About the Karman Line. After more reading I thing Gravity is also an important factor. The base idea is: 1a The higher you go, the thiner the atmosphere. 1b The thiner the atmosphere, the more speed you need to still fly (aerodynamically). 2a The faster you rotate around a planet, the stronger the Centrifugal Force. 2b "Orbital Velocity" is the speed at wich the Centrifugal Force completly cancels the gravitational pull (and not more, otherwise you would fly off into space). Asuming the best existing wing (specific craft) or possible wing (absolute physical maximum): When the speed needed to lift you (aerodynamically) reaches your orbital velocity, you reached the Karman Line. Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted April 22, 2012 Report Share Posted April 22, 2012 Re: More space news! Yah, I got that, but any idea of how to do the computation? One could just say the Karman Line is proportional to the atmospheric pressure at sea level and inversely proportional to the square root of gravity at sea level, but ... Quote Link to comment Share on other sites More sharing options...
Christopher Posted April 22, 2012 Report Share Posted April 22, 2012 Re: More space news! Yah' date=' I got that, but any idea of how to do the computation? One could just say the Karman Line is proportional to the atmospheric pressure at sea level and inversely proportional to the square root of gravity at sea level, but ...[/quote'] The complete formula is on Wikipedia, even with explanation what each one means. And it's even just "Square your airspeed, multiply it by everything else, divide by two". Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted April 22, 2012 Report Share Posted April 22, 2012 Re: More space news! Ah, nice! Quote Link to comment Share on other sites More sharing options...
Escafarc Posted April 23, 2012 Report Share Posted April 23, 2012 Re: More space news! http://www.youtube.com/watch?v=B2fpT25t5wA Quote Link to comment Share on other sites More sharing options...
Zeropoint Posted April 23, 2012 Report Share Posted April 23, 2012 Re: More space news! You heard the man; time travel is possible! Quote Link to comment Share on other sites More sharing options...
SteveZilla Posted April 23, 2012 Report Share Posted April 23, 2012 Re: More space news! You heard the man; time travel is possible! I really need to ask a serious physicist how that can be, since that would mean that the universe could, at some point in time, contain more than 100% of it's matter. Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted April 23, 2012 Report Share Posted April 23, 2012 Re: More space news! Why would that matter? Quote Link to comment Share on other sites More sharing options...
Christopher Posted April 23, 2012 Report Share Posted April 23, 2012 Re: More space news! Why would that matter? Because then it is possible that mater already has traveled backwards in time, wich could potentially lead to an infinite grwoth of the universe. It would also mean that through time travel the laws of Thermodynamic are avoidable. You spend energy in the future (one that never comes to pass because you create an alternate timeline) to get more energy now. Also in other space news with seperate thread: http://www.herogames.com/forums/showthread.php/89452-Planetary-Resources Quote Link to comment Share on other sites More sharing options...
SteveZilla Posted April 23, 2012 Report Share Posted April 23, 2012 Re: More space news! Why would that matter? Because then it is possible that mater already has traveled backwards in time, which could potentially lead to an infinite growth of the universe. It would also mean that through time travel the laws of Thermodynamic are avoidable. You spend energy in the future (one that never comes to pass because you create an alternate timeline) to get more energy now. Also in other space news with separate thread: http://www.herogames.com/forums/showthread.php/89452-Planetary-Resources Also, consider this: A scientist sets up an experiment to send a single atom back in time, and he chooses an atom of an element that undergoes natural radioactive decay. He has a "fully primed" time experiment. Before he sends off his little atom of X, he receives X in his experiment! Now, the atom X in in two places at once? Remember also, that X is subject to radioactive decay. What happens if the "first" X (Xf now) decays *before* he sends it back in time? Will the "second" X (Xs now) immediately appear to also decay? Will the scientist remember receiving an undecayed Xs at all? Or, looked at from another angle, the scientist puts off sending Xf back in time, waiting to see if he can get it to decay, whereupon he will send on of the decay components back in time instead. What happens? If Xf decays, this would create a paradox, since he already has Xs, undecayed, from the future. Will postponing the decision to send Xf back *prevent* Xf from ever decaying since that would lead to a paradox? Quote Link to comment Share on other sites More sharing options...
Zeropoint Posted April 24, 2012 Report Share Posted April 24, 2012 Re: More space news! Just because it could yield highly counter-intuitive results doesn't mean it's not true . . . remember how reluctant people were to accept the idea of quantum superposition? Quote Link to comment Share on other sites More sharing options...
McCoy Posted April 24, 2012 Report Share Posted April 24, 2012 Re: More space news! remember how reluctant people were to accept the idea of quantum superposition? Actually, no, I don't. Quote Link to comment Share on other sites More sharing options...
tkdguy Posted April 24, 2012 Author Report Share Posted April 24, 2012 Re: More space news! Private spacecraft launch to ISS delayed. Quote Link to comment Share on other sites More sharing options...
Zeropoint Posted April 24, 2012 Report Share Posted April 24, 2012 Re: More space news! Actually, no, I don't. It was a bit before my time, too . . . but there are STILL people who have a very hard time accepting, for instance, that things can be truly random, that there aren't "hidden variables". Private spacecraft launch to ISS delayed. Well, better than having it fail for lack of testing, I guess. Quote Link to comment Share on other sites More sharing options...
dmjalund Posted April 24, 2012 Report Share Posted April 24, 2012 Re: More space news! Just because it could yield highly counter-intuitive results doesn't mean it's not true . . . remember how reluctant people were to accept the idea of quantum superposition?I do and don't simultaneously Lucius 1 Quote Link to comment Share on other sites More sharing options...
John T Posted April 24, 2012 Report Share Posted April 24, 2012 Re: More space news! I do and don't simultaneously *puts you in the box with the possible cat... maybe* Quote Link to comment Share on other sites More sharing options...
Querysphinx Posted April 25, 2012 Report Share Posted April 25, 2012 Re: More space news! You heard the man; time travel is possible! CAll me back when someone can adequately define the word "time." We infer time from our experience of sequential displacement, but how this experience comes about is an utter mystery. We can predict the behavior of objects as their speed changes in relativistic ways compared to other things, but we still haven't the foggiest idea of what causes "intervals." Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted April 25, 2012 Report Share Posted April 25, 2012 Re: More space news! Ardbeg distillery to test maturation of their product in zero-G. Quote Link to comment Share on other sites More sharing options...
Cancer Posted April 25, 2012 Report Share Posted April 25, 2012 Re: More space news! Scotch, scientists, and rockets. Now there's a proposal worth signing on. Quote Link to comment Share on other sites More sharing options...
SteveZilla Posted April 25, 2012 Report Share Posted April 25, 2012 Re: More space news! And alcohol can be used as rocket fuel! Quote Link to comment Share on other sites More sharing options...
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