Can Negative Momentum exist in our universe without going into space inversion like in a singularity? Can you have matter which has a property of negative mass?
Momentum is a vector. Negative momentum in the +X direction would simply be positive momentum in the -X direction.
I don’t think you get what I was asking… I shouldn’t have really said negative momentum cause it’s mass I was asking about which is a component of it. What I meant to say was the second question (negative mass), but saying Negative Momentum will probably get more people to respond to this thread.
Not in reality. That is to say there are some equations that can be solved with by giving an element negative mass, but it is purely theoretical. Nothing in the physical universe possesses negative mass.
The closest you can get is some definitions of a tachyon, a solution to special relativity with imaginary mass (ie when squared it still has a negative sign), and similarly a intangible speed that is faster than light.
The answer to your question is… We don’t know yet. There’s a lot of physicists, myself included, who very much hope that there is such a substance, since it would have all sorts of interesting properties, and allow a host of technologies (warp drive, anyone?), but one thing physicists must learn is that things aren’t always how we hope.
How is the mass of an antimatter particle expressed? If it is positive–didn’t I read that there are spontaneous creations and destruction in a vacuum of antiparticles and particles? If so, how do we have conservation of mass, if they both have positive mass? (Maybe I should just buy a textbook, it’s been xx years since I studied this stuff.)
The mass of an anti-particle is the same as the mass of the corresponding particle. The answer to your question is that mass just isn’t conserved; it’s energy that’s conserved. When a particle/anti-particle pair pops out of the vacuum, they take some energy from it for a short period of time, as allowed by the indeterminancy principle. Eventually, they’ll recombine and give the energy back.
momentum = mV which if you don’t allow - velocity you need - mass but isn’t also equal to something else (another equation perhaps for light) - maybe something that can be negative. too tired now maybe I’ll try to look it up tomorrow.
I have heard of negative energy (the stuff you need to hold open a wormhole?) and since energy is mass - their you go just get this stuff moving and you have negative mo
That’s what I was referring to, k2dave: If you have negative mass (energy), you can stabilize a wormhole, or build a warp drive, or do all sorts of other fun things. Doesn’t say anything about the existence of such stuff, though, since we don’t have stable worm holes or warp drives yet.
Chronos I thought (-) energy was proven - IIRC in an experiment using 2 plates very close together something was done to create pressure causing the 2 plates to want to move together. The theory was that (-) energy was somehow induced between the plates and that was causing a pressure diffrence. I personally think it was just the pressure of light or even air on both sides of the plates pressing it in but (again IIRC) this was considered proof of (-) energy. Even hear of this?
k2dave your thinking of zero-point energy, that’s energy extracted from quantum vacuum fluctuations of the electromagnetic field. The experiment your talking about is the Casimir effect. It might be related to the vacuum energy which causes the long range lambda force. But it isn’t negative energy.
My question continues… with the current answer being there is no negative mass. 
The volume between the plates has a negative energy density.
Imaginary why don’t you learn something before you post imaginary facts.
Ring I thought is was just of lower density but still positive.
Positive with respect to what? What’s the energy density of the vacuum? if the the energy density of the normal vacuum is defined to be zero and the energy density between the plates is less than this, then what would your informed opinion be?
It’s not defined to be zero.
rho(vacuum) = M4c3/h3 = 1013 [M/proton mass]4 gm/cc
This density is more than 1091 gm/cc.
Boys! Boys! Haven’t your physics books told you that you can zero your potential energy wherever you like? Vacuum potentials included. Let’s all be friends!
In every field except relativity, you can set the zero of energy anywhere you like, but toss gravity into the mix, and you start having experimental consequences. The Casimir effect does occur, and is usually regarded as representing a negative energy density between the plates, but there’s some loopholes in the definitions that makes it uninteresting for “negative mass” questions. I don’t remember the details, I’m afraid; I would have to look them up.
Imaginary, what’s M in that equation?
http://www.npl.washington.edu/AV/altvw43.html
There is, however, a way of suppressing part of the vacuum fluctuations, of making “empty” space more empty, using a technique based on the Casimir effect.
Since the energy density of normal vacuum is defined to be zero, the vacuum between the metal plates actually becomes a region of negative energy density.
http://www.hawking.org.uk/text/public/warps.html
Because there are fewer virtual particles, or vacuum fluctuations, between the plates, they
have a lower energy density, than in the region outside. But the energy density of empty space far away from the plates, must be zero. Otherwise it would warp space-time, and the universe wouldn’t be nearly flat.
http://www.aip.org/enews/physnews/1998/split/pnu398-2.htm
We don’t know of any such object, but physicists have detected small regions of space characterized by a very slightly negative energy density (the so called Casimir effect;
http://www.lns.cornell.edu/spr/1999-02/msg0015120.html
you need to use a non-obvious renormalization trick to do the calculation, but in the end you get a negative energy density, and if you actually went out and measured the energy density, it would indeed be negative
http://www.sciam.com/askexpert/physics/physics34.html
We can get small amounts of negative energy in the laboratory (the Casimir effect)
http://dhushara.tripod.com/book/upd/sciamf/scans/wrp.htm
Can a region of space contain less than nothing? Common sense would say no; the most one could do is remove all matter and radiation and be left with vacuum. But quantum physics has a proven ability to confound intuition, and this case is no exception. A region of space, it turns out, can contain less than nothing. Its energy per unit volume-the energy density-can be less than zero.
http://www.hawking.org.uk/text/public/warps.html
Because there are fewer virtual particles, or vacuum fluctuations, between the plates, they
have a lower energy density, than in the region outside. But the energy density of empty space far away from the plates, must be zero. Otherwise it would warp space-time, and the universe wouldn’t be nearly flat.
Hey, I understand that it is traditional to define the zero of potential in empty space at infinity from our mass. That’s all it is, though, traditional. Just because Einstein was able to solve the vacuum equations by assuming as such doesn’t mean some other person has to. You could define a metric whose energy-momentum tensor has values that are at any constant “C” you want. It’s just much more of a pain in the posterior to do since you’d have to invent a slightly different theory of GR.
Thus, I stick by my previous statement.