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Mass / Negative(?) mass


Myouya

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One question that often raises to my mind is "Is it possible to have negative mass?".
Evidently, at first it sounds ridiculous, having less than nothing. But, from what I have heard, physics still work if you use a negative term for mass.

For instance, E=MC^2 [Where E is energy, M is mass, C is the fastest velocity]
Maybe this equation is an exception because the terms on the right side will always be positive, because of the "^2".
But for equation F=M*A [F is force, M is mass, A is acceleration] the idea suggests that an object can have be under a negative force.
I have thought, if you try to apply a force to an object with negative mass to push it in a direction, would it instead be pulled in the opposite direction?
 

[Edit]

I think I made a mistake earlier, in E=MC^2 it isn’t only that C is squared, right? In that case, the result could indeed mean negative energy is also plausible.

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  • 2 weeks later...

This reminds me of the phlogiston theory. People tried to explain why some things get heavier when they are burned and tried to explain it by saying that something with negative mass is lost, thereby increasing mass. This was shown to not be the case.

Concerning mass, you should distinguish between mass and weight. Weight is what we usually mean by mass in everyday life. Mass in physical terms is hard to understand, because it is used in different ways. Generally, as far as I know negative energy/mass is used in a couple of theories but I don't know if there is any testable evidence on that.

Maybe you'll find this interesting?
http://www.edition-open-sources.org/sources/5/24/

If you are really interested in it, and know higher maths, I can also send you the full article.

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1 minute ago, Illusion of Terra said:

This reminds me of the phlogiston theory. People tried to explain why some things get heavier when they are burned and tried to explain it by saying that something with negative mass is lost, thereby increasing mass. This was shown to not be the case.

Concerning mass, you should distinguish between mass and weight. Weight is what we usually mean by mass in everyday life. Mass in physical terms is hard to understand, because it is used in different ways. Generally, as far as I know negative energy/mass is used in a couple of theories but I don't know if there is any testable evidence on that.

Maybe you'll find this interesting?
http://www.edition-open-sources.org/sources/5/24/

If you are really interested in it, and know higher maths, I can also send you the full article.

Thank you for the comment.
I was having the differenciation of weight and mass in mind for the experiment, you are right that I should have made it clearer.
I will see what's on that link.

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  • 3 weeks later...

From my understanding it all boils down to the whole - * - = + due to the fact that energy is never lost only redistributed in one form, or another. So even if you have negative mass its still not 0. The only particles known to be truly without mass are photons aka light.

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3 hours ago, Illusion of Terra said:

Photons are crazy in many respects. I once worked on trying to combine photons to create stronger ones which sounds a lot more exciting then it was.

That sounds really cool, and fun mixed with just the slightest element of danger.

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  • 2 weeks later...

@Keiko  Just saw this (published about a week ago):

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.084501#fulltext

Apparently, simple sound waves when they pass through solids and fluids have negative mass too

They say that the sound wave/particle "carries (negative) mass. Moreover, this is not due to the usual equivalence of mass and energy in relativity: the effect survives in the nonrelativistic limit. And, finally, it is not a quantum effect, because the formalism of Ref. [1] applies unaltered to classical waves."

Edited by Illusion of Terra
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Just read the article. It was very interesting I certainly learned something. Though sound waves do not normally move anything with Mass they can move photons through super fluids which is very interesting. 

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