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[Lastgengamer]

Could this help to make use of antimatter, or at least better understand it? This sounds exciting.

 

[Spiritwalker]

I have no idea what this means, but it sounds cool.

 

[zeemumu]

Does gravity make it move up?

 

[habithipster]

Now possible.

Loved Tom Cruise's cameo in this movie.

 

[D1renegade]

Why is there no video of this?

 

[All Possible Ways]

Could this help to make use of antimatter, or at least better understand it? This sounds exciting.

Sorry, it's nothing cool like that. Antimatter has positive mass, btw.

Does gravity make it move up?

Not really, see this post:

Not if both gravitic and inertial mass are negative...

m a_r = - G m Mt / r² u_r

so

a_r = - G Mt / r² u_r

The "m" factor disappear. The mass has no effect on the effect of earth gravity...

Also, the equality of gravitational and inertial masses is known to be true with a precision better than one part in 10^11.

 

[FrozenCell]

now let's see a solid which would swing right back at you

 

[cakely]

Not if both gravitic and inertial mass are negative...

m a_r = - G m Mt / r² u_r

so

a_r = - G Mt / r² u_r

The "m" factor disappear. The mass has no effect on the effect of earth gravity...

Ok, you lost me there.

Gravity applies force to mass, right?

What's the difference between the the force being applied in the article (the push) and the force of gravity?

 

[All Possible Ways]

Ok, you lost me there.

Gravity applies force to mass, right?

What's the difference between the the force being applied in the article (the push) and the force of gravity?

What he means is the following: you know that F=ma, such that for fixed force, a larger mass has a smaller acceleration, right?

For the gravitational force, however, the force law itself is proportional to the mass, as in

F= -GMm/r^2.

Putting this in F=ma, you see that

-GMm/r^2 = ma

and so you may cancel the mass "m" on both sides. This means that the acceleration felt is independent of the mass of the object, so that in the absence of air friction, objects of different masses fall at the same rate.

This depends on the "m" that appears on both sides of the equation being the same thing. In principle, they could be slight different, but all experiments to date confirm the equality to incredible precision.

 

[cakely]

What he means is the following: you know that F=ma, such that for fixed force, a larger mass has a smaller acceleration, right?

For the gravitational force, however, the force law itself is proportional to the mass, as in

F= -GMm/r^2.

Putting this in F=ma, you see that

-GMm/r^2 = ma

and so you may cancel the mass "m" on both sides. This means that the acceleration felt is independent of the mass of the object, so that in the absence of air friction, objects of different masses fall at the same rate.

This depends on the "m" that appears on both sides of the equation being the same thing. In principle, they could be slight different, but all experiments to date confirm the equality to incredible precision.

Ok, thank you, I followed that.

 

[eot]

Could this help to make use of antimatter, or at least better understand it? This sounds exciting.

First of all, antimatter has positive mass.
Secondly, no, this doesn't have anything to do with antimatter, and it's all regular matter and it's all positive mass. "Effective mass" is a very useful concept, but it's a simplification. There are complex dynamics in the system that cause it to behave similar to as if it had a negative mass.

 

[HotHamBoy]

Pics or it didn't happen.

 

[jstripes]

Teenagers are made of negative mass?

 

[Narroo]

Okay, as someone who knows a bit about this stuff, this is a misleading article.

What they created was a negative effective mass. No particles here actually have negative mass, they didn't break the laws of Physics. Rather, they have a rather contrived system that under certain conditions, if you apply F=ma to a simplistic model, you get something that looks like negative mass. In actuality, if you did a more detailed and complex analysis, you'd find that the Rd atoms still have their normal positive mass.

Effective masses are used in mathematical models where the mathematical details of the dynamics are prohibitively complex, and simpler models give correct results if you just tweak parameters a bit. For example, in metals, 'relatively simplistic' models, such as the Lindhard Equation, can be used to obtain fairly accurate results despite being in principle wrong, if assume the electron has a mass up to 1,000x greater than what it actually is.

 

[TheThreadsThatBindUs]

I am guessing it only behaves as if it has negative mass for some reason, and that the article is being sensationalist (like most science articles). I think this because wouldn't negative mass also result in the nullification (or reversal) of gravitational force on the object?

I dunno... kinda. The Wikipedia article says that positive mas attracts negative and positive mass, however, negative mass repels both. So in theory, two masses of the same magnitude but one positive and the other negative, would accelerate forever in the direction of the positive mass.

I'm pretty sure this isn't negative mass, however, and that you're right in that it's atoms behaving in a similar way to negative mass (i.e. displaying some of the properties).

 

[Narroo]

I am guessing it only behaves as if it has negative mass for some reason, and that the article is being sensationalist (like most science articles). I think this because wouldn't negative mass also result in the nullification (or reversal) of gravitational force on the object?

Yeah, exactly. There's a major difference between an effective mass and an actual mass.

 

[Plywood]

Negative ass

Oh god, I laughed.

 

[TheThreadsThatBindUs]

Yeah, exactly. There's a major difference between an effective mass and an actual mass.

The Wikipedia article has already been updated with this shamefully sensationalist claim. Lol.

 

[Breakage]

Wait until the adult entertainment industry gets ahold of this.

 

[ItIsOkBro]

What happens if you jump on a trampoline made from negative mass

 

[Kid Ying]

Wow. Today had huge news on science here, but i think this one is much more incredible than the other. Anxious to read the paper.

 

[farmerboy]

So a fart that follows you around has a negative mass?

Serious question.

 

[Black-Wind]

Soooo ... any vid of this stuff in action?

Cause I can't see how this works in practice.

 

[.JayZii]

I'm not entirely sure what that means, and I feel like it would look underwhelming if I saw it, but that sounds like a big development.

 

[DiscoJer]

I remember back in thermodynamics class in college, there was a section in the textbook on an experiment that created a negative (Kelvin) temperature. It didn't have any practical value, it was just showing that sometimes science is weird.

 

[Narroo]

I remember back in thermodynamics class in college, there was a section in the textbook on an experiment that created a negative (Kelvin) temperature. It didn't have any practical value, it was just showing that sometimes science is weird.

It comes from the definition of temperature. Temperature is usually defined as the reciprocal of the energy derivative of entropy. If you have an finite number of states, this can become negative. Spin 1/2 particles in a magnetic field - basic paramagnetism - can do this.

In -most- real world systems, the number of available states is unlimited, so you don't see negative temperatures.

 

[Dynomutt]

If we can combine this negative mass fluid with VantaBlack which negates reflection/absorbs all light and a mysterious lab accident we can have our first metahuman! Who will volunteer?