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Scientists create fluid with 'negative mass'

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I did not realize we have freezing lasers.

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Oh god...

baronflies.jpg

Soon we'll have Baron Harkonnens running around all over the place.  

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Should eventually have some interesting applications.  

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I wonder how long the effect lasts when the temperature of the fluid starts rising.

 

From the linked article:

"He and his colleagues created the conditions for negative mass by cooling rubidium atoms to just a hair above absolute zero, creating what is known as a Bose-Einstein condensate. In this state, predicted by Satyendra Nath Bose and Albert Einstein, particles move extremely slowly and, following the principles of quantum mechanics, behave like waves. They also synchronize and move in unison as what is known as a superfluid, which flows without losing energy."

Almost sounds like perpetual motion once you give it a kick start.

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Push it, and instead of moving away from you it will accelerate towards you in apparent defiance of the laws of physics.

So, it's a cat.

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5 hours ago, Totah Dine said:

Oh god...

baronflies.jpg

Soon we'll have Baron Harkonnens running around all over the place.  

 

Surely that's, floating all around the place!

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Reminds me of when they created stuff at negative absolute temperature. Negative mass sounds more palpable to me. Also EB condensate is nothing new.

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So, if according to Newton's second law the condensate goes towards the force pushing it, what happens according to the third? Does it "swallow" the pushing force? 

Theoretically it should pull towards itself. 

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4 hours ago, Parsec said:

So, if according to Newton's second law the condensate goes towards the force pushing it, what happens according to the third? Does it "swallow" the pushing force? 

Theoretically it should pull towards itself. 

The third law should continue to hold normally, meaning the condensate creates an equal and opposite force. This means if the original force was created by a positive mass, the force should push it away from the negative mass. As the force on the negative mass pushes it towards the positive mass, this leads to a condition dubbed ``runaway motion''. Although it seems physically implausible, it is theoretically feasible as the total energy, momentum, etc. of the system is conserved. Wikipedia has a nice article on the subject, as usual.

In the context of the experiment described above, it is important to note that the researchers obtained a negative effective mass. This does not mean that the Rb atoms acquired an actual negative mass, this means that because of the various interactions (spin-orbit, electrostatic, magnetic dipole, etc.) in the Rb gas, when an external force is applied the Rb atoms (and actually, only a fraction of the Rb atoms present), the Rb atoms subjected to that force move as if they had a negative mass.

If the external force becomes so strong that it completely overpowers all the internal forces in the Rb gas, then the Rb will resume moving ``normally''.

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Negative mass? Ha! 

Yeah, and I just farted an inverted Möbius strip.

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18 hours ago, sepulchrave said:

The third law should continue to hold normally, meaning the condensate creates an equal and opposite force. This means if the original force was created by a positive mass, the force should push it away from the negative mass. As the force on the negative mass pushes it towards the positive mass, this leads to a condition dubbed ``runaway motion''. Although it seems physically implausible, it is theoretically feasible as the total energy, momentum, etc. of the system is conserved. Wikipedia has a nice article on the subject, as usual.

In the context of the experiment described above, it is important to note that the researchers obtained a negative effective mass. This does not mean that the Rb atoms acquired an actual negative mass, this means that because of the various interactions (spin-orbit, electrostatic, magnetic dipole, etc.) in the Rb gas, when an external force is applied the Rb atoms (and actually, only a fraction of the Rb atoms present), the Rb atoms subjected to that force move as if they had a negative mass.

If the external force becomes so strong that it completely overpowers all the internal forces in the Rb gas, then the Rb will resume moving ``normally''.

Thank you sepulchrave, your explanations are always appreciated. That is so super cool!

While reading the article you linked, I thought "well, we could use it for a spaceship" and a second later I read that Forward of course already proposed it. Well, nomen est omen

 

Question: I get the runaway motion, but that is solely based on gravitational interactions. 

If instead for instance we apply a force to the negative mass, greater than the gravitational force, are you sure about the third law? 

I'm possibly confused, but if normally according to the third law F(a) = -F(b), written also as m(a)a = -m(b)a, shouldn't it become in this specific case m(a)a = -[-m(b)a] => m(a)a = m(b)a? 

Shouldn't both of the forces in this case then have the same direction?

 

To be fair, if we'd really exert a force on a negative mass, we'd probably be nullified, so we shouldn't even care about the third law!

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3 hours ago, Parsec said:

Thank you sepulchrave, your explanations are always appreciated. That is so super cool!

While reading the article you linked, I thought "well, we could use it for a spaceship" and a second later I read that Forward of course already proposed it. Well, nomen est omen

 

Question: I get the runaway motion, but that is solely based on gravitational interactions. 

If instead for instance we apply a force to the negative mass, greater than the gravitational force, are you sure about the third law? 

I'm possibly confused, but if normally according to the third law F(a) = -F(b), written also as m(a)a = -m(b)a, shouldn't it become in this specific case m(a)a = -[-m(b)a] => m(a)a = m(b)a? 

Shouldn't both of the forces in this case then have the same direction?

 

To be fair, if we'd really exert a force on a negative mass, we'd probably be nullified, so we shouldn't even care about the third law!

The argument is based on gravitational interactions because that is a non-contact force that applies to large objects.

And yes, both forces should have the same direction - that is how we get runaway motion. One object pushes the other, the other pulls the first.

It is difficult to apply a force other than gravity to this situation without introducing additional complexities. Electrostatic or magnetic forces can result in charge distribution within the objects, changing the forces; while contact forces (which are essentially electrostatic as well) are very difficult to model mathematically.

There are some simple alternative examples: You can imagine putting a negative mass object on a spring. As the spring stretches the spring force tries to pull the mass back towards the centre, but because the mass is negative this causes it to accelerate away, stretching the string even further... basically the spring will always get stretched and break.

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I want to see some anti gravity applications resulting from this.

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On April 18, 2017 at 8:39 AM, Totah Dine said:

Oh god...

baronflies.jpg

Soon we'll have Baron Harkonnens running around all over the place.  

One of the best lines in that movie: when the Emperor says, "Bring in that floating fat man, the Baron." 

I wonder if true anti-gravity could ever become a reality and what that would mean for travel and other means of transportation? 

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