Negative Mass
students.tools
students.tools
See, e.g., https://physics.stackexchange.com/a/8616
A ball that flies upwards has been shown (as a balloon). A kind of stable replacement of orbital motion, if it exists, would be cool to see!
Who gave this absolute savage a website, I nearly choked on my coffee.
Uh, what?
What would need to happen for you to claim that negative mass "doesn't work"? Some infinities somewhere? A division by zero in some place?
https://www.youtube.com/watch?v=kvihUBO7rGo
Cosmological model with negative masses:
- https://januscosmologicalmodel.com/negativemass
Simulation:
- https://www.youtube.com/watch?v=vJgzH99t9w8
Based on Souriau symplectic geometry (where inverting energy is equivalent to inverting the arrow of time):
Which is why only photons can travel at the speed of light, since they have zero mass.
But going with that idea, wouldn’t that mean that something with negative mass can then go faster than the speed of light?
Would that explain why we can never observe something with negative mass? Because it’s going faster than the speed of light?
This is exactly the kind of mind games why I loved cosmology so much in college.
No. You can construct a theory of tachyons (particles that go faster than light) using special relativity, but they have imaginary masses!
The key is that the quantity that actually appears in the equations you refer to in special relativity is the mass squared. So ordinary objects have positive mass squared, light has zero mass squared, and tachyons have negative mass squared.
(Note that this means that some of the things that the article under discussion here says about "negative mass" are only valid in Newtonian mechanics, not in relativity.)
Thanks for that explanation!
No. The negative mass squared means the mass itself, the square root of the mass squared, is imaginary.
I love the idea of negative mass ( because i love symetries in the laws of nature) but i've got a hard time believing the geniuses of the early 20th century haven't already explored the idea.
... and wonderful?
Here's a good video on it, comfortingly entitled "The Most Efficient Way to Destroy the Universe": https://www.youtube.com/watch?v=ijFm6DxNVyI
The good news is you probably won’t see it coming because nerves are slower than the speed of light. Hard to say if you’d experience anything after.
And I don't see how this relates to the previous examples. In my mind, impact and friction has nothing to do with gravity.
The physics of negative mass/energy are paradoxical to the point that they mathematically enable transluminal transport.
I think so. For most purposes, we can build intuition for special relativity without having to do the math. (General is more fucked.) We don’t understand negative energy/mass enough to even do that.
This is why I want to know if antimatter falls up. Or I guess it might fall down but repel regular matter in which case it'll be very hard to detect.
Are there other types of Antimatter that focus on different properties?
We don't know that. It may have the regular charge but after computing the force it may experience the opposite behavior via F=ma since the mass is negative.
We don't really know if the charge is opposite or the mass. Blindly using the equations you may get similar results depending where you stick the negative.
Also, I seem to recall Dirac predicting the existence of antimatter because some solution to an equation had an m^2 term and when you take a square root to solve for m there are two solutions. Then the positron came along and this was forgotten and people just assumed it had positive charge rather than negative mass.
Both theory and experimental validation. Their interaction with electric fields, their interaction with gravity, conservation laws, and so on.
Here is a contrived example calculating a hypothetical quantity X = m * Y.
Suppose we observe that X is always negative.
By your logic, we would then assume that Y is always negative.
This is true if m is never negative, but it is somewhat possible that we would eventually find a situation where m is negative and Y is positive.
In a given interaction, charge is always conserved. So we see interactions where an electron and a positron collide they produce a chargeless photon. So it must have the opposite charge to an electron
Is there energy in an electric field? If so it must be signed or it wouldn't cancel out.
The energy contained in the electromagnetic field is nonnegative: as I understand it, within a given volume, it's simply the sum of the photon energy of all of the photons.
Meanwhile, electrons and positrons exist in their own particle field, and have both positive mass energy and nonnegative kinetic energy. When an electron and positron annihilate and produce photons, they convert their combined mass energy into kinetic energy in the photons. The only thing that gets "canceled out" is the positive and negative electric charge.
https://www.riken.jp/en/news_pubs/research_news/pr/2022/2022...
The force between two masses, F is equal to G multiplied m-sub-1 multiplied by m-sub-2, and then all of that divided by the square of the distance between m-sub-1 and m-sub-2. Here G is the gravitational constant and the number being positive indicates a force toward, say, the first partner, m-sub-1.
Now, imagine m-sub-2 is negative mass.
Our force then becomes negative, so a force away from the first partner, m-sub-1.
BUT ...
Acceleration is equal to force divided by mass. Here the mass, m-sub-2 is negative, but so is the force. And so the acceleration is back to being positive and the negative mass "falls toward" the positive mass of m-sub-1.
In other words, positive matter ends up being a "falling toward" field.
Negative matter, however, well, run the numbers, only do everything from the m-sub-2 vantage point. The positive mass, m-sub-1, flees! Even as it attracts the other one.
And so once you have a negative/positive pair, they lock on, one fleeing, one chasing. One ends up with ever increasing positive kinetic energy, the other with ever increasing negative kinetic energy (all starts to sound a little silly here) and they cancel out, from a distance.
Gets wacky once you start imagining this for charged particles, which immediately bunch up into staggering Coulombs of negatively-charged nega-mass particles, and ditto for the positively-charged nega-mass particles. They just rapidly self-sort into these clumps due to the "electrostatic repulsion" going up against negative inertia. The EM force quickly dominates.
These two blazing opposite poles of charge, Q-pos and Q-neg, should naturally attract one another, but for that pesky negative inertia again.
And so all of the negative mass in the universe sorts into Q-pos and Q-neg, then promptly tries to approach the speed of light fleeing from one another, leaving just the slightest of electrical fields evident, but always asymptotically approaching zero as they more or less banish themselves to the further regions of normal matter.
(Some normal matter would be torn along for the ride)
It's a fun thought experiment.
The weird part is that it can be negative, so we already know quasi-particles with negative mass.
This quasi particle with negative mass and negative charge is a fermion so it's mathematically equivalent to a quasi particle with positive mass and positive charge. We call them "holes" and people that work with semiconductors think about "holes" instead of weird particles with negative mass.
Anyway, inside semiconductors they slow down and follow the conservation of energy law, they don't get faster and faster like in the simulation. The weird behavior of the simulation is not realistic.