I can’t wrap my head around exotic matter, which I figure is a pretty common affliction. Let’s say I have a brick of exotic matter lying on a table - well, maybe not lying on a table, say lying on a low ceiling - and I push it with my finger. The brick moves towards my finger, causing it to push my finger towards the brick, which in turn pushes the brick towards my finger, and so forth times infinity.
Is this correct? If so, what would actually happen?
Don’t be dissing exotic matter. It’s absolutely vital to state-of-the-art technobabble. If you’ve got some exotic matter, and some form of “modulation”, you’re ready to face anything.
ETA: Seriously, I have a hard time visualizing negative inertia as well. (And do theoretical tachyons qualify as exotic matter? God almighty, I knew more physics when I was twelve than I do now. My life is a failure.)
First, tell me how you managed to form the stuff into a brick, to begin with. What are the internal forces between the individual exotic particles like?
But yeah, the fact that you have your brain tangled up over questions like this is actually a good sign. Most people, on first hearing of exotic matter, will just say something like “What’s the big deal? So it falls up, instead of down. What’s so special about that?” (which, incidentally, is untrue: Exotic matter falls the same way as normal matter). Confusion such as your own is inevitable, once you reach a certain level of understanding.
Oh, and as a footnote: The easiest way to get a large conglomeration of exotic matter particles would be for them all to have an electric charge, all with the same sign. They’d all be repelled from each other, and therefore squished all together. Of course, such an intense concentration of charge would probably severely challenge our current models of the world: We can’t do anything remotely similar with normal matter.
Is exotic matter the same as dark matter? Or anti-matter? Or both or neither? My only sources for science are sci-fi, and I don’t usually read modern sci-fi, TV documentaries, and the SDMB.
I heard you need a special license to own exotic matter.
It does? It isn’t repelled by gravity? I thought that was kinda the point.
So the answer to my question is “we don’t have a flippin’ clue”?
Neither. Dark matter is matter that we cannot observe but believe exists because it explains other observations. Antimatter is matter consisting of atoms whose nuclei contain antiprotons (protons with a negative charge) and are surrounded by antielectrons (electrons with a positive charge). Exotic matter is matter with negative mass.
I should know better than to ever even glance at physics.
It is repelled by gravity, if by “repelled”, you mean “has a force acting on it in the direction away from the source of the gravitational field”. But now, ask yourself what effect such a force would have on an object with negative mass.
I hope the non-modern sci-fi you’re referring to isn’t by E. E. “Doc” Smith. He spun a good yarn, but he managed to get all of those concepts, and a few others, thoroughly confused, and if he’s your primary source for understanding exotic matter, then he’s going to get you even more confused.
I hadn’t heard of exotic matter before this thread. Is it theoretical, or is there some evidence that it exists?
Whoah. Trippy.
But seriously, I thought the reason it’s repelled by gravity was that it has negative mass. That is to say, it is attracted by gravity just like you and me, but since it has negative mass, the attraction causes it to move away from the source. Like how it tries to move towards me when I push it. Why is it repelled by gravity then?
Because it has negative mass. Remember, the force of gravity on an object is proportional to the mass of the object. Remember also that F = ma.
Purely theoretical. It would be extremely interesting if it did exist, which in itself is pretty solid evidence that it doesn’t. That is to say, some of the consequences of it existing would be so interesting, that if it did exist, it’d be almost impossible for us to miss it.
Something here just isn’t clicking for me.
I have enough physics behind me to grasp what you’re saying…I think. But the consequences just don’t match what you’re saying in my head.
What I’m getting is that the force of gravity between a chunk of exotic matter and a chunk of regular matter would be inverted due to the negative mass. OK, simple enough. That, however, results in their repelling eachother - it would fall up. I apparently lack the background to grok how the same negative mass would have it repelled by gravity, so it fell down in response to the now negative force.
Or else I’ve forgotten the physics I learnt and am completely misunderstanding the situation, of course.
Perhaps it would be easier to forget about exotic matter for a moment? Consider just an ordinary chunk of matter, in some gravitational field (such as the Earth’s). The gravitational force is proportional to the lump’s mass, and the acceleration of the lump is equal to the force on it divided by its mass. Put it together, and the mass cancels out, so, as Galileo observed, the acceleration of an object in a gravitational field is independent of its mass.
No matter what an object’s mass is, it’ll accelerate downward, at the same rate. No matter what its mass is: Even if the mass is negative. A negative number can cancel itself out just as well as a positive number can. Since mass shows up both in the formula for gravitational force, and in the formula for acceleration, it cancels out, and the negative signs cancel out, too.
Shaping the exotic matter should be quite simple. Simply gather enough of it by nudging it in the opposite direction of the pile and detonate a shaped charge in the midst of the pile. Voila, the exotic matter explodes into one solid piece.
Gotcha.
I still don’t really get that. The force exerted on the exotic matter is negative, because the mass is negative, and yet the matter will still fall in the same direction as normal matter? So does this mean that exotic matter somehow interacts differently with the gravitational field, or is it as simple as “negative force divided by negative mass = positive acceleration”?
I don’t see the thing squirting away from you. The force has to be negligible.
Look, my cell phone is 2 cm from hand right now; it’s not exactly breaking any speed records as it sloooowly is attracted to my hand. Make that force negative;
it’s going to recede just as slowly, which is basically not visible to the human eye.
That’s it. Gravity follows the same rules for everything, and when you apply those rules to exotic matter, you get negative force divided by negative mass.
You’re just thinking of the gravitational force. But there are a bunch of other forces at work on your cell phone. For a normal, positive mass, cell phone, there are going to be places where the forces are at equilibrium, and those equilibria will almost always be stable, so if it’s sitting on your desk, for instance, it’s just going to stay there. For an exotic cell phone, though, although there will still be equilibrium points (for instance, the phone sitting on the underside of your desk), the equilibrium will not be stable any more, so your phone is going to eventually go zipping off in some direction or another.
There is another aspect of regular and exotic matter interaction: unlike M/AM, which yields enormous amounts of liberated energy due to E=mc^2, one gram of matter touching negative one gram of exotic matter simply cancels each other out.
Touch a brick of exotic matter, and your hand disappears!
:eek:
That’s the first I heard of this. Why, how, where does it go, and, well, cite?