Physicists at the University of Washington created a liquid with negative mass. Push it, and unlike all physical objects in the world that we know of, it doesn't accelerate in the direction of the push. She accelerates into reverse side. This phenomenon is rarely created in the lab and can be used to explore some of the more complex concepts about the cosmos, says Michael Forbes, associate professor, physicist and astronomer at the University of Washington. The study appeared in Physical Review Letters.

Hypothetically, matter can have negative mass in the same sense that electric charge can be both negative and positive. People rarely think about it, and our everyday world shows only the positive aspects of Isaac Newton's Second Law of Motion, according to which the force acting on a body is equal to the product of the mass of the body and the acceleration imparted by this force, or F = ma.

In other words, if you push an object, it will accelerate in the direction of your push. The mass will accelerate it in the direction of the force.

“We are used to this state of affairs,” says Forbes, anticipating a surprise. "With negative mass, if you push something, it will accelerate towards you."

Conditions for negative mass

Together with colleagues, he created the conditions for negative mass by cooling rubidium atoms to a state of almost absolute zero and thus creating a Bose-Einstein condensate. In this state, predicted by Shatyendranath Bose and Albert Einstein, particles move very slowly and, following the principles quantum mechanics behave like waves. They also synchronize and move in unison as a superfluid that flows without energy loss.

Led by Peter Engels, a professor of physics and astronomy at the University of Washington, scientists on the sixth floor of Webster Hall created these conditions by using lasers to slow particles down, making them cooler and allowing hot, high-energy particles to escape like steam, cooling the material even further.

The lasers captured the atoms as if they were in a bowl less than a hundred microns in size. At this stage, the superfluid rubidium had the usual mass. The rupture of the bowl allowed the rubidium to escape, expanding as the rubidium in the center was forced outward.

To create the negative mass, the scientists used a second set of lasers that pushed the atoms back and forth, changing their spin. Now, when the rubidium runs out fast enough, it behaves like it has a negative mass. "Push it and it will accelerate into reverse direction Forbes says. "It's like rubidium hitting an invisible wall."

Elimination of major defects

The method used by the University of Washington scientists avoided some of the major flaws found in previous attempts to understand negative mass.

"The first thing we realized is that we have a tight control over the nature of this negative mass without any other complications," says Forbes. Their study explains, already from the position of negative mass, similar behavior in other systems. Increased control gives researchers new tool to develop experiments to study similar physics in astrophysics, using the example neutron stars, and cosmological phenomena like black holes and dark energy, where experiments are simply not possible.

Hypothetical wormhole in spacetime

AT theoretical physics, is the concept of a hypothetical substance whose mass has the opposite value of the mass normal matter(just like an electric charge can be positive and negative). For example, -2 kg. Such a substance, if it existed, would disturb one or more, and would exhibit some strange properties. According to some speculative theories, negative mass matter can be used to create ( wormholes) in space-time.

Sounds like absolute fiction, but now a group of physicists from the University of Washington, the University of Washington, OIST University (Okinawa, Japan) and Shanghai University, which exhibits some of the properties of a hypothetical material with negative mass. For example, if you push this substance, it will accelerate not in the direction of the application of force, but in the opposite direction. That is, it accelerates in the opposite direction.

To create a substance with the properties of a negative mass, scientists prepared a Bose-Einstein condensate by cooling rubidium atoms to almost absolute zero. In this state, the particles move extremely slowly, and quantum effects begin to appear at the macroscopic level. That is, in accordance with the principles of quantum mechanics, particles begin to behave like waves. For example, they synchronize with each other and flow through the capillaries without friction, that is, without losing energy - the effect of the so-called superfluidity.

In the laboratory of the University of Washington, conditions were created for the formation of a Bose-Einstein condensate in a volume of less than 0.001 mm³. The particles were slowed down by a laser and waited for the most energetic of them to leave the volume, which further cooled the material. At this stage, the supercritical fluid still had a positive mass. If the hermeticity of the vessel was breached, the rubidium atoms would scatter into different sides, since the central atoms would push the extreme atoms outward, and they would accelerate in the direction of the application of force.

To create a negative effective mass, physicists used a different set of lasers that changed the spin of some atoms. As the simulation predicts, in some areas of the vessel, the particles should acquire a negative mass. This is clearly seen in the sharp increase in the density of matter as a function of time in the simulations (in the lower diagram).

Figure 1. Anisotropic expansion of a Bose-Einstein condensate with different coefficients adhesion forces. Real Results experiments are in red, prediction results in simulation are in black

The bottom diagram is an enlarged section of the middle frame in the bottom row of Figure 1.

The bottom diagram shows a 1D simulation of total density versus time in the region where dynamic instability first appeared. Dotted lines separate three groups of atoms with velocities

at a quasi-moment

Where is the effective mass

starts to become negative (upper line). Shown is the point of minimum negative effective mass (middle) and the point where the mass returns to positive values(bottom line). The red dots indicate the places where the local quasi-momentum lies in the region of the negative effective mass.

The very first row of graphs shows that during physical experiment the matter behaved in exact accordance with the results of the simulation, which predicts the appearance of particles with a negative effective mass.

In a Bose-Einstein condensate, particles behave like waves and therefore propagate in a different direction than normal particles of positive effective mass should propagate.

In fairness, it must be said that physicists repeatedly recorded during experiments, but those experiments could be interpreted in different ways. Now the uncertainty is largely eliminated.

Scientific article April 10, 2017 in the journal Physical Review Letters(doi:10.1103/PhysRevLett.118.155301, available by subscription). A copy of the article before submitting to the journal on December 13, 2016 at free access at arXiv.org (arXiv:1612.04055).

Recommended to watch at 1280 x 800 resolution

"Technique-youth", 1990, No. 10, p. 16-18.

Scanned by Igor Stepikin

Tribune of bold hypotheses

Ponkrat BORISOV, engineer
Negative Mass: Free Flight to Infinity

Articles on this topic have been appearing in foreign and Soviet physics journals from time to time for more than 30 years. But oddly enough, they still do not seem to have attracted the attention of popularizers. But the problem of negative mass, and even in strictly scientific setting- a great gift for lovers of the paradoxes of modern physics, and science fiction writers. But such is the property special literature: the sensation in it can remain hidden for decades ...

So, we are talking about a hypothetical form of matter, the mass of which is opposite in sign to the usual one. The question immediately arises: what does this actually mean? And it immediately becomes clear: it is not so easy to correctly define the concept of negative mass.

Undoubtedly, it must have the property of gravitational repulsion. But it turns out that this alone is not enough. AT modern physics four types of mass are strictly distinguished:

gravitational active - the one that attracts (if it is positive, of course);

gravitational passive - the one that is attracted;

inert, which acquires a certain acceleration under the action of an applied force (a \u003d F / m);

finally, Einstein's rest mass, which sets the total energy of the body (E = mC 2).

In the framework of generally accepted theories, they are all equal in magnitude. But it is necessary to distinguish between them, and this becomes clear just when trying to determine the negative mass. The fact is that it will be completely opposite to the usual one only if all four of its types become negative.

Based on this approach, in the very first article on this topic, published back in 1957, English physicist X. Bondy determined the basic properties of "minus-mass" by rigorous proofs.

It may not even be very difficult to repeat them here, because they are based only on Newtonian mechanics. But this will clutter up our story, and then there are a lot of physical and mathematical "subtleties". Therefore, let's go straight to the results, especially since they are quite clear.

Firstly, “minus matter” must gravitationally repel any other bodies, that is, not only with negative, but also with positive mass (whereas ordinary matter, on the contrary, always attracts matter of both types). Further, under the action of any force, up to the force of inertia, it must move in the direction opposite vector this strength. And finally, its total Einstein energy must also be negative.

Therefore, by the way, it should be emphasized that our amazing matter- not antimatter, the mass of which is still considered positive. For example, by modern ideas, "Anti-Earth" from antimatter would revolve around the Sun in exactly the same orbit as our home planet.

All this is almost obvious. But then the incredible begins.

Let's take the same gravity. If two ordinary bodies attract and approach, and two antimasses repel and scatter, then what will happen in the gravitational interaction of masses of different signs?

Let it be simplest case: a body (let's say a ball) made of matter with a negative mass -M is behind an object (let's call it a "rocket" - now we'll find out why) with an equal positive mass +M. It is clear that the gravitational field of the ball repels the rocket, while it itself attracts the ball. But it follows from this (this is again rigorously proved) that the whole system will move along a straight line connecting the centers of two masses, with constant acceleration, proportional to the strength gravitational interaction between them!

Of course, at first glance, this picture of spontaneous, causeless motion “proves” only one thing: antimass with the properties that we attributed to it in the definition from the very beginning simply cannot exist. After all, we have received, it would seem, a whole bunch of violations of the most immutable laws.

Well, isn't the law of conservation of momentum, for example, being completely openly violated here? Both bodies, for no reason at all, rush in the same direction, while nothing moves in the opposite direction. But remember that one of the masses is negative! But this means that its impulse, regardless of speed, has a minus sign: (-M) V, and then total impulse two-body system is still zero!

The same is true for the total kinetic energy of the system. While the bodies are at rest, it is equal to zero. But no matter how fast they move, nothing changes: the negative mass of the ball, in full accordance with the formula (-M)V 2 /2, accumulates a negative kinetic energy, which exactly compensates for the increase in the positive energy of the rocket.

If all this seems absurd, then maybe we will “knock out a wedge with a wedge” - let's try to confirm one absurdity with another? Since the sixth grade, we know that the center of equal point masses (positive, of course) is in the middle between them. So - how would you like the following output? The center of equal point masses of DIFFERENT SIGN lies, although on a straight line passing through them, but not inside, but OUTSIDE of the segment connecting them, at the point ±Ґ ?!

Well, is it easier?

By the way, this conclusion is already quite elementary, and everyone can repeat it if they wish, owning physics at the level of the same sixth grade.

Anyone who does not believe in a word and wants to make sure that all calculations are correct can refer to one of latest publications on this topic - article American physicist R. Forward "Rocket engine on the substance of negative mass", published in the translated magazine " Aerospace Engineering» No. 4 for 1990.

But, perhaps, the sophisticated reader thinks that even without any calculations he understood where the "linden" was slipped to him? Indeed: in all these elegant arguments, the question is hushed up: where did such a wonderful mass come from? After all, whatever its origin, it will take energy to “extract”, “manufacture” or, say, deliver it to the scene of action, which means ...

Alas, sophisticated reader! Energy, of course, will be needed, but again negative. Nothing can be done: in Einstein's formula for the total energy of the body E = Ms 2, our wonderful mass has the same minus sign. This means that the "production" of a pair of bodies with EQUAL masses of DIFFERENT signs will require ZERO total energy. The same applies to delivery, and to any other manipulations.

No - no matter how paradoxical all these results, strict conclusions state that the presence of antimass does not contradict not only Newtonian mechanics, but also general theory relativity. It was not possible to find any logical prohibitions on its existence.

Well - if the theory "allows", then let's think, for example, - what can happen when physical contact two identical particles of matter with plus and minus masses? With "ordinary" antimatter, everything is clear: annihilation will occur with the release of the total energy of both bodies. But if one of the two equal masses is negative, then their total energy, as we just understood, is zero. But WHAT will happen to them in reality - this is already a question that goes beyond the theory.

The outcome of such an event can only be known empirically. It is impossible to “calculate” it - after all, we have no idea about the “mechanism of action” of the negative mass, its “ internal arrangement”(as, however, we do not know this about the mass of the usual). Theoretically, one thing is clear: in any case, the total energy of the system will remain zero. We have the right to put forward only a HYPOTHESIS, as the same Forward does. According to his assumption, physical interaction here it does not lead to annihilation, but to the so-called "nullification", that is, the "quiet" mutual annihilation of particles, their disappearance without any release of energy.

But, we repeat, only an experiment could confirm or refute this hypothesis.

For the same reasons, we don't know anything about how to "make" negative mass (if at all possible). The theory only states that equal mass opposite sign in principle, they can arise without any energy costs. And as soon as such a pair of bodies appears, it will fly, accelerating, in a straight line to infinity...

R. Forward in his article has already “designed” a negative mass engine that can take us to any point in the Universe at any acceleration that we set. It turns out that all that is needed for this is ... a pair of good springs (all interactions of the "minus-mass" with the usual one through elastic forces, of course, are also calculated in detail).

So, let's place our wonderful mass, equal in size to the mass of the rocket, in the middle of its "engine compartment". If you need to fly forward, stretch the spring from the back wall and hook its negative mass body. Immediately because of their "perverted" inertial properties it will rush not where it is being pulled, but straight ahead opposite direction, dragging the rocket along with an acceleration proportional to the force of the spring tension.

To stop acceleration, it is enough to unhook the spring. And to slow down and stop the ship, you need to use a second spring attached to the front wall of the engine compartment.

And yet there is a partial refutation of the "free engine"! True, it comes from a completely unexpected side. But more about that at the end.

In the meantime, let's look for places where there could be large amounts of negative mass. Such places are suggested by the giant voids found on large-scale three-dimensional maps of the distribution of galaxies in the Universe - the most interesting phenomena in themselves. As can be seen from fig. 2, the dimensions of these cavities, which are also simply called "bubbles", are about 100 million light years (whereas the dimensions of our Galaxy are about 0.06 million light years). Thus, on the largest scale, the Universe has a "foamy" structure.

The boundaries of the bubbles are clearly marked by clusters a large number galaxies. There are practically no bubbles inside, and if they are found there, then these are very unusual objects. They are characterized by the spectra of powerful high-frequency radiation. It is now believed that the bubbles contain "failed" galaxies or gas clouds of ordinary hydrogen.

But is it possible to assume that the "foamy" structure of the Universe is the result of its formation from the same number of particles of negative and positive mass? By the way, a very attractive consequence follows from such an explanation: the total mass of the Universe has always been and remains zero. Then the bubbles are natural places for minus-mass, the particles of which tend to disperse as far as possible from each other. And the positive mass is pushed to the surface of the bubbles, where, under the influence of gravity forces, it forms galaxies and stars. Here we can recall the article by A. A. Baranov, which appeared back in 1971 in No. 11 of the journal Izvestia Vuzov. Physics". There is considered cosmological model Universe with particles having masses of both signs. Using this model, the author explains the experimental estimates of the cosmological constant and the Hubble redshift, as well as some anomalous phenomena observed in interacting galaxies.

Another possible symptom large quantities negative mass - the presence of very fast "currents" in large-scale structures of the Universe. Thus, the supercluster containing our Galaxy "flows" at a speed of 600 km/s relative to the background at rest. relic radiation. Such a speed does not fit into the framework of theories of the formation of galaxies from cold dark matter. R. Forward proposes to try to explain this phenomenon taking into account the collective repulsion of superclusters from bubbles containing negative mass.

So, negative matter can only fly apart. But this, it turns out, is the partial refutation of many of the conclusions that were discussed. After all, the property of gravitational repulsion of particles of matter, whatever their nature, inevitably leads to the fact that these particles cannot come together under the influence of gravitational forces. Moreover, since a particle of negative mass under the action of any force moves in the direction opposite to the vector of this force, then ordinary interatomic interactions cannot bind such particles into “normal” bodies.

But we hope that the reader nevertheless received pleasure from all these arguments ...

Hypothetical wormhole in spacetime

In the laboratory of the University of Washington, conditions were created for the formation of a Bose-Einstein condensate in a volume of less than 0.001 mm³. The particles were slowed down by a laser and waited for the most energetic of them to leave the volume, which further cooled the material. At this stage, the supercritical fluid still had a positive mass. In the event of a leak in the vessel, the rubidium atoms would scatter in different directions, since the central atoms would push the extreme atoms outward, and they would accelerate in the direction of the application of force.

To create a negative effective mass, physicists used a different set of lasers that changed the spin of some atoms. As the simulation predicts, in some areas of the vessel, the particles should acquire a negative mass. This is clearly seen in the sharp increase in the density of matter as a function of time in the simulations (in the lower diagram).

Figure 1. Anisotropic expansion of a Bose-Einstein condensate with different cohesive force coefficients. The real results of the experiment are in red, the results of the prediction in the simulation are in black

The bottom diagram is an enlarged section of the middle frame in the bottom row of Figure 1.

The bottom diagram shows a 1D simulation of total density versus time in the region where dynamic instability first appeared. Dotted lines separate three groups of atoms with velocities at the quasi-momentum , where the effective mass starts to become negative (upper line). The point of minimum negative effective mass is shown (middle) and the point where the mass returns to positive values ​​(bottom line). The red dots indicate the places where the local quasi-momentum lies in the region of the negative effective mass.

The very first row of graphs shows that during the physics experiment, matter behaved exactly as simulated, which predicts the appearance of particles with a negative effective mass.

In a Bose-Einstein condensate, particles behave like waves and therefore propagate in a different direction than normal particles of positive effective mass should propagate.

In fairness, it must be said that physicists repeatedly recorded results during experiments when the properties of matter of negative mass were manifested, but those experiments could be interpreted in different ways. Now the uncertainty is largely eliminated.

Scientific article published on April 10, 2017 in the journal Physical Review Letters(doi:10.1103/PhysRevLett.118.155301, available by subscription). A copy of the article before submission to the journal was placed on December 13, 2016 in the public domain at arXiv.org (arXiv:1612.04055).

Scientists from the United States claim to have created a substance with a negative mass in the laboratory. This substance is a liquid with a very unusual properties. For example, if you push this fluid, then it will receive a negative acceleration, that is, backward, not forward. Such oddity could tell scientists a lot about what's going on inside at least strange objects such as black holes and neutron stars.
However, can something have negative mass? Is it possible?

Theoretically, matter can have a negative mass in the same way that an electric charge can have a negative or positive value.

On paper, this works, but there is a heated debate in the world of science about whether the very assumption of the existence of something with negative mass violates the fundamental laws of physics. For us, ordinary people, this concept seems too complicated to understand.

differential law mechanical movement or, more simply, Newton's second law is expressed by the formula A=F/M. That is, the acceleration of a body is equal to the ratio of the force applied to it to the mass of the body. If you set negative meaning mass, then the body, quite logically, will receive a negative acceleration. Just imagine, you hit the ball, and it rolls on your leg.

However, what seems alien to us need not be impossible, and the above theoretical exercises are the best way to prove that negative mass can exist in our Universe without violating the general theory of relativity.

The desire to understand all this gave rise to active attempts by researchers to recreate the negative mass in the laboratory, as we see, even with some success.

Scientists from the University of Washington said they have succeeded in obtaining a liquid that behaves exactly as a body with negative mass should behave. And their discovery may finally be used to study some strange phenomena in the depths of the universe.

To create this strange liquid, scientists used lasers to cool rubidium atoms to near absolute zero, creating what is called a Bose-Einstein condensate.

In this state, the particles move incredibly slowly and strangely, following the strange principles of quantum mechanics rather than classical physics, that is, they begin to behave like waves.

The particles also synchronize and move in unison, forming a superfluid substance that can move without losing energy through friction.
Scientists have used lasers to create a superfluid low temperatures, as well as in order to place it in a bowl-shaped field less than 100 microns across.

As long as the supermatter remained placed in this space, it had an ordinary mass and was quite consistent with the concept of a Bose-Einstein condensate. Until he was forced to move.

Using a second set of lasers, the scientists forced the atoms to move back and forth, as a result of which their spin changed and rubidium, having overcome the barrier of the "bowl", rapidly splashed out. However, as if it had a negative mass. According to scientists, the impression was such that the liquid stumbled upon an invisible barrier and repelled from it.

Thus, the researchers confirmed the assumptions about the existence of negative mass, but this is only the very beginning of the journey. It remains to be seen whether the fluid behavior under laboratory conditions is repeatable and reliable enough to test some assumptions about negative masses. So, do not rejoice ahead of time, other teams need to repeat the results on their own.

One thing is for sure, physics is getting more and more interesting and worth taking an interest in.

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