Scientists create a fluid with negative mass

Posted on 15 Apr 2017


Today’s true strange news award goes to the creation of a fluid with negative mass. 

Washington State University physicists have created a fluid with negative mass, which is exactly what it sounds like. Push it, and unlike every physical object in the world we know, it doesn’t accelerate in the direction it was pushed. It accelerates backwards.


What does it mean for a fluid to accelerate backward?

Researchers in the US say they’ve created a fluid with negative mass in the lab… which is exactly as mind-bending as it sounds.

What it means is that, unlike pretty much every other known physical object, when you push this fluid, it accelerates backwards instead of moving forwards. … how can something have negative mass?

Hypothetically speaking, matter should be able to have negative mass in the same way that an electric charge can be either negative or positive. On paper that works, but it’s still debated in the science world whether negative mass objects can really exist without breaking the laws of physics – something that’s not helped by the fact that the very concept is hard for us mere humans to wrap our heads around.

Isaac Newton’s Second Law of Motion is often written as the formula f=ma, or force equals an object’s mass times its acceleration.

If we rewrite it as acceleration is equal to a force divided by the object’s mass, and make the mass negative, it would have negative acceleration – just imagine sliding a glass across a table and having it push back against your hand.

This doesn’t make it very clear. Viscosity is essentially fluid friction and acceleration is the rate of change of velocity with time, so I first visualized a fluid that gets thicker, more viscous, over time as a force is applied against it. It would seem to turn from a thin liquid to a thicker one, perhaps all the way until it felt like a solid. 

That would be wild, but they appear to be saying something even stranger. A fluid with negative mass accelerates toward the force pushing against it, instead of just resisting with increasing friction.

However, just because it seems foreign to us, doesn’t mean it’s impossible, and previous theoretical research has shown some early evidence that negative mass could exist within our Universe without breaking the theory of general relativity.

More than that, many physicists think that negative mass could be linked to some of the weird things we’ve detected in the Universe, such as dark energy, black holes, and neutron stars.
As a result, researchers have been actively trying to recreate negative mass in the lab, with some early success.

But now researchers from Washington State University say they’ve successfully managed to get a fluid of superchilled atoms to act as though it has negative mass – and suggest it could finally be used to study some of the stranger phenomena happening in the deep Universe.

“What’s a first here is the exquisite control we have over the nature of this negative mass, without any other complications,” said one of the researchers, Michael Forbes.
To create this strange fluid, the team used lasers to cool rubidium atoms to a fraction above absolute zero, creating what’s known as a Bose-Einstein condensate.

In this state, particles move incredibly slowly and follow the strange principles of quantum mechanics, rather than classical physics – which means they start to behave like waves, with a location that can’t be precisely pinpointed.

The particles also … sync up and move in unison, forming what’s known as a superfluid – a substance that flows without losing energy to friction.
The team used lasers to keep this superfluid at the icy temperatures, but also to trap it in a tiny bowl-like field measuring less than 100 microns across.

While the superfluid remained contained in that space it had regular mass and, as far as Bose-Einstein condensates go, was pretty normal. But then the team forced the superfluid to escape.

Using a second set of lasers, they kicked the atoms back and forth to change their spin, breaking the ‘bowl’ and allowing the rubidium to come rushing out so fast that it behaved as if it had negative mass.

“Once you push, it accelerates backwards,” said Forbes. “It looks like the rubidium hits an invisible wall.”


Crazy. You push it away and it flows at you. Where’s the video of that? One person commented that matter with negative mass could be invisible.

… on purely geometrical grounds, negative mass structures could be invisible for a positive mass observer (and vice-versa)


Some are calling the negative mass fluid “corbomite” from the Corbomite Manuver episode in the first Star Trek series. 

The ship is about to be destroyed and the alien, Balok, is counting down…

BALOK [OC]: Three minutes.
KIRK: All right, Doctor. Let’s hope we have time to argue about it. Not chess, Mister Spock, poker. Do you know the game? Ship to ship.

UHURA: Hailing frequencies open, sir.

KIRK: This is the Captain of the Enterprise. Our respect for other lifeforms requires that we give you this warning. … Since the early years of space exploration, Earth vessels have had incorporated into them a substance known as corbomite. It is a material and a device which prevents attack on us. If any destructive energy touches our vessel, a reverse reaction of equal strength is created, destroying

BALOK [OC]: You now have two minutes.

KIRK: Destroying the attacker! It may interest you to know that since the initial use of corbomite more than two of our centuries ago, no attacking vessel has survived the attempt. Death has little meaning to us. If it has none to you then attack us now. We grow annoyed at your foolishness. …


The alien decides to let them live and invites them over for tea.

Back to our story, is matter with negative mass the same as anti-matter? Anti-matter is a real substance which powers the engines of the fictional starship Enterprise. 

Antimatter particles have opposite charges compared to ordinary matter, but antimatter still has positive mass. Probably.

Antimatter is anti- a lot of things, but it’s not supposed to be antigravity.

An antimatter particle does have the opposite electric charge of its ordinary matter counterpart. But the mass of both particles should be precisely equal. When an antiparticle meets its ordinary particle partner, they annihilate in a burst of energy, equal to their masses squared in accordance with Einstein’s famous formula E=mc2.

Because you get energy out by destroying antimatter, you have to put energy in to create antimatter, which implies that antimatter’s mass must be positive. That’s one reason why most physicists immediately dismiss the idea that antimatter could have negative mass.

But thanks to some technical complications in the definition of mass, the case is not closed. 


Would a cube of matter with negative mass have antigravity? Would it fall up? 

Positive masses attract all other masses, while negative masses repel all other masses, so yes.

Negative mass would also repel itself, which seems a good reason we wouldn’t have very much around now. It would accelerate apart same way positive mass accelerates together due to gravity.

If negative mass’ acceleration increases as it spreads across the universe, that may explain dark energy. Dark energy is a name given to the unknown force causing the universe to accelerate at an ever increasing rate.

Follow that with your imagination. You might at first think negative mass just keeps expanding and accelerating forever, but we know that does not happen to positive mass, there is a limit to acceleration. No particle with (positive) mass can accelerate to the speed of light. As you get closer, it takes more and more energy, and you never get there. For anti-mass accelerating, I assume it hits this same limit.

Imagine the outwardly expanding ever accelerating bubble of negative mass. At some extreme amount of energy, I’d imagine it reaches a critical maximum possible distance from itself and this defines the edge of the universe. We could speculate that this collision creates a white hole, an infolding of space-time, a new universe. 

This may have already happened. Some scientists are considering that there have been multiple big bangs.

The Big Bang, a huge explosion which created matter and time, is thought to have occurred 14 billion years ago.

Some scientists believe that it is just the latest in a line of Big Bangs and that the universe is far older, maybe as old as 986 billion years. However the multiple Big Bang theory suggests they could have happened simultaneous in different places, as part of a wide ‘multiverse.’


When too much positive mass gets too close, it forms a black hole, a singularity, from which, with some quantum exceptions, not even light can escape. 

The fact that light has a speed limit, to me, is evidence of a size limit of the universe, an outer boundary. At some point, when too much negative mass gets too far apart, it hits that boundary, and explodes inward, filling all space in the bubble of the universe, creating a white hole, which I call an everywherity.  

Perhaps this keeps happening and there are remnants, clues, echoes. 

I once heard a theory that the fabric of space-time is made up of microscopic black holes and white holes popping into and out of existence.

Now we are going to get really crazy, but follow me into the ultimate strange universe concept, if you can, the Xenographic universe. In my vision of the universe, one of those little white holes that pops into our universe is our universe itself. This is what happens when a critical amount of negative mass hits the barrier and the bubble implodes. The universe physically echoes into itself, once again. The universe is made up of very short lived microscopic black holes and white holes, and each one is a time the universe itself collapsed in a big crunch black hole or expanded into a everywherity. Let go of your concepts of time and size, and see if you can imagine a universe composed of its own infinite births and deaths.

Sometimes I believe in as many as six impossible things before breakfast.

– Alice

I know, that’s absurd and impossible, but for some reason, I want to believe in everywherities.


Update 4/21/2017 Gizmodo points out that behaving as negative mass is not the same as being negative mass:

The reason this phenomenon has the name negative effective mass is because of the equation used to describe what’s going on, explains Hossenfelder. If you look at the energy of the system and do a little calculus on it using the regular laws of physics, the mass term would be negative—but also dependent on other terms. Negative effective mass is not an innate property of the atoms themselves.


There is something called the Duck Test. If something behaves as if it has negative mass, it might not be a duck. If a few atoms or rubidium weigh as much as a duck, however, you know it’s made of wood, and therefore, it is… a witch. 

I love blogging.