/sci/ - Science & Math

>>3134898
Yes. The same system has been proposed to de-orbit satellites.

>>3132934
I am beginning to wonder if you only post simply to be contrary.

>>3132913
It has nothing to do with being in water.

>>3132773
Tying weights to yourself does help.

It is very commonly used among the elderly and for rehabilitation.

A city in space.

Only 600 billion dollars or somesuch. Houses 20,000 people and performs scientific experiment and space based construction.

download link related
http://www.mediafire.com/?cyjsmnbi1jt0cbo

>>3117942
Are there any stories of scuba divers being taken into the deep by wildlife?

Giant squid attacks? Sperm whales? That sort of thing?

Survival horror games.

I prefer to just not play them. I got as far as the diner in Silent Hill, and called it quits there. I don't think I could even touch penumbra.

http://simple.wikipedia.org/wiki/Quantum_computer

>>3112153
>>3112101
And what if it turns out that the brain is nothing more than simple hardware that the consciousness runs on? The equivalence of computer software running on computer hardware.

>You are standing in a field looking at the stars. Your arms are resting freely at your side, and you see that the distant stars are not moving. Now start spinning. The stars are whirling around you and your arms are pulled away from your body. Why should your arms be pulled away when the stars are whirling? Why should they be dangling freely when the stars don't move?

http://en.wikipedia.org/wiki/Mach%27s_principle

Something that you all might find interesting to read about.

This thread would have been improved a hundredfold if you had written Buddhism at the top.

>>3111600
Yes. In fact a recent experiment provided additional evidence that the Earth "twists" spacetime as it spins.

http://science.nasa.gov/science-news/science-at-nasa/2011/04may_epic/

Of course, the gravitational pull of a spacecraft is exceedingly minor compared to stars and planets.

>>3103258
There is probably a button/toggle/switch on your camera that looks like a flower. Turning it on will put your camera in Macro mode and you will be able to take photos of small objects up close without all the blurriness. Or at least, with less blurriness.

>>3103008
Lasers would be best used for destroying incoming guided projectiles. I'd estimate a realistic point defense laser being about 2 meters across, 100MW and about 250nm wavelength, firing in 0.1 second pulses every 0.5 seconds.

It'd take about a tenth of a second for this laser to burn through 25cm's of Aluminium at 250km's, 3cm's at 500km's. With an array of point defense lasers, you should be able to quickly kill the guidance systems on incoming missiles. Each laser would require about 500MW's peak output.

Advances in laser technology would of course, increase the range and power and efficiency. Efficiency would be really nice for reducing the size of the reactor you need to power these things. Right now lasers are ~20% efficient [or worse].

>>3102924
Right now, these materials only work at one specific frequency of light.

>>3102859
Lasers are short range weapons in space due to the fact that you cannot perfectly focus a laser. The beam of light does not travel in a perfectly straight line.

To increase the range of your laser, you need to change the wavelength, increase the size of your emitter and increase the power output. 3m lens, 1 GW output and ultraviolet wavelength [100nm] will have a maximum effective range of about 4,000km's.

[Keep in mind that lasers are not 100% efficient, so if your laser is 1GW, you'll need 2-3GW's to actually power it. The extra GW's of energy? That's almost all waste heat. Hope your radiators are up to the task.]

>>3102832
Mass Effect is also full of handwavium.

The waste heat from the equipment and personnel aboard the spacecraft will very very quickly fill up those "heat batteries". You'd have minutes, maybe an hour or two, before you cook yourself to death in the Normandy. Not hours or days or weeks. The exact amount of time depends on how much heat you're storing, and how much heat you're generating. The math is all there, you're welcome to take a stab at it for an exact answer, if you'd like.

It makes far far more sense to use those sorts of batteries in the middle of combat rather than having your fragile radiators exposed. When the fight is over [hopefully] within a half hour, you extend your radiators and cool off.

>>3102849
>Which is true, but in certain situations it would actually prove fairly useful, especially if you had good intelligence, and you could be harder to see if you were defending a planet by aiming the heat towards the surface, as well as making the radiators themselves, that should be very delicate and vulnerable, better protected.

Well, there isn't really any sort of defensive position in space. Any object traveling along a known orbit is trivial to destroy by simply releasing some really small and cold junk while on an intercepting orbit with the target. And besides, lets assume you have these stealthships of yours in low Earth orbit. What are they going to do when I push an asteroid from the belt into a crossing orbit with Earth? I can stay out as far as Jupiter, see anything coming a mile away, and just launch as many weapons at Earth as I feel like.

An alternative option for stealth in space, rather than trying to cool down the hull, is simply to accelerate to relativistic velocities. You'll be so close behind your own wave of light that by the time someone sees you, they don't have much time to act. For example if Pluto, 5 billion kilometers away, fired a relativistic projectile at Earth at 99% the speed of light, we'd see them launch the relativistic projectile ~4 hours, 38 minutes later. We'd be hit by the relativistic projectile about 4 hours, 40 minutes later, or about 2 minutes after we saw it.

>>3102670
Being able to cool the hull down to ~3 kelvin is pretty much an impossibility. It takes some extremely complicated machinery and techniques to cool things down to this temperature in a laboratory. Techniques that do not work when applied to the hull of a spacecraft.

I seriously doubt you could cool the hull of a spacecraft much below 100 kelvin and still have all the machinery operating within it. Keep in mind that the process of refrigerating the hull is, itself, going to generate even more waste heat. The best you can accomplish would simply be reduced detection range.

>I've also heard that along with normal radiator panels it is also possible to create radiator 'strips' along a ships hull, is there any truth to this either?
You don't even need purposely made radiators and your spacecraft will still radiate heat. Yes, you can design your radiators however you like them, the question is one of efficiency. You want as much surface area as possible to radiate as much heat as possible. A radiator that runs alongside the hull radiates about half of its heat back into the ship, which is why you don't want to put them there.

>>3097970
OP, do what I did as a kid. Grab a jar from the kitchen, fill it with dirt, then dig up an ant nest and grab the queen, some workers, some larva and stick'em all in there.

They don't like light, so be sure to cover the glass with black paper or something to encourage them to dig along the sides.

http://www.youtube.com/watch?v=OLkDQUOu_Y0

youtube link for people who can't load BBC

>>3085651
Something a lot of people tend to gloss over is the inverse square law in relation to our radio broadcasts.

Yeah, in 2000 years, our broadcasts will have reached pretty far, but I seriously doubt you'd be able to pick us out from the background noise unless you were specifically looking right at us.

>>3085621
>how is that for science? of course it WILL work, oxygen is still going to the brain, so it will be kept alive. there is no need to actually do it IRL, its cruel.

This was done at time when they weren't entirely sure how the body worked. [It was also done by Russians, and without the oversight of an ethics board.] These types of experiments helped give us the understanding we have today about how the body functions.

We probably could have figured out that you can theoretically keep a head alive so long as its getting the blood and nutrients it needs. These guys proved it experimentally, before they really even understood the fundamental processes.

Anyways, you'd probably never get an experiment like this past an ethics board these days.

>>3085706
Well, to each his own, but I enjoyed Starship Troopers a great deal more than The Forever War.

I may not agree with Heinlein's ideas of a model society, but he writes a more engaging story than Joe Haldeman does.