bose einstein
Scientists have created a fluid with negative mass – but what does it tell us?
The fluid, which defies everyday laws of motion, is a rare achievement and provides a platform to study an otherwise hypothetical form of matter
By Hannah Devlin

Scientists have created a fluid that exhibits the bizarre property of “negative mass” in an experiment that appears to defy the everyday laws of motion.

Push an object and Newton’s laws (and common experience) dictate that it will accelerate in the direction in which it was shoved.

“That’s what most things that we’re used to do,” said Matthew Forbes, a physicist at Washington State University and co-author of the paper, which shows that normal intuitions do not always apply to physics experiments. “With negative mass, if you push something, it accelerates toward you.”

Negative mass has previously cropped up in speculative theories, including those suggesting the existence of wormholes, a form of cosmological shortcut between two points in the universe. Just as electric charge can be either positive or negative, matter could, hypothetically, have either positive or negative mass.

For an object with negative mass, Newton’s second law of motion, in which a force is equal to the mass of an object multiplied by its acceleration (F=ma) would be experienced in reverse.

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Washington State University Physicists create '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.

The phenomenon is rarely created in laboratory conditions and can be used to explore some of the more challenging concepts of the cosmos, said Michael Forbes, a WSU assistant professor of physics and astronomy and an affiliate assistant professor at the University of Washington. The research appears today in the journal Physical Review Letters, where it is featured as an “Editor’s Suggestion.”

Hypothetically, matter can have negative mass in the same sense that an electric charge can be either negative or positive. People rarely think in these terms, and our everyday world sees only the positive aspects of Isaac Newton’s Second Law of Motion, in which a force is equal to the mass of an object times its acceleration, or F=ma. In other words, if you push an object, it will accelerate in the direction you’re pushing it. Mass will accelerate in the direction of the force.

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Physicist Create a Fluid With Negative Mass

Physicists from Washington State university have created a liquid with negative mass meaning that when you push it, instead of accelerating in that direction, it accelerates backwards.

Matter can have a negative mass much the same way that particles can be negatively charged. Newton’s second law of motion (F=ma) tells us that mass will accelerate in the direction of the force so we can deduce that matter with a negative mass would do the opposite and accelerate against the force.

To create the conditions for negative mass, Peter Engels and his team started by cooling rubidium atoms to a Bose-Einstein condensate meaning they reached very near absolute 0. The researchers used lasers to trap the atoms in an area less than 100 microns across and allow high energy particles to escape cooling them further. Then to create negative mass, the physicists applied a second set of lasers to change the way atoms spin back and forth. They then removed the first set of lasers causing the rubidium to rush out and appear to hit some sort of invisible wall; behaving as if it had a negative mass.

What’s great about this is the control we have over the negative mass without any other complications. This gives us a new tool we can use to engineer experiments in astrophysics looking at neutron stars, black holes, dark energy and a lot more.

anonymous asked:

Could you explain the difference between fermions and bosons? What differs from an integer spin and a half-integer spin?

There are lots of differences beyond the spin of a particle, including how many degrees of freedom each one has and how they behave statistically (obeying either Fermi-Dirac or Bose-Einstein statistics). But two big differences that may interest you are:

1.) Fermions have distinct antiparticle counterparts: antifermions. An electron (Fermion) has a positron (anti-Fermion) as its counterpart. Bosons don’t; a photon is its own antiparticle, for example.

2.) The Pauli exclusion principle – that no two quantum particles can occupy the exact same quantum state – only applies to fermions. You can’t have multiple electrons in the same quantum state, which is why atomic structure is so interesting. But you can have multiple bosons in the same state, which is how you get a Bose-Einstein condensate!

This is a pretty good question; if we get enough notes (likes and shares) on this, I will use it for this upcoming Saturday’s Ask Ethan!

Simulating a black hole

40 years ago Stephen Hawking predicted that black holes emit a special kind of radiation. Consequently black holes are theoratically able to shrink and even vanish. This radiation arises when virtual particles (pairs of particles developing because of quantum fluctuations inside the vacuum; usually they nearly instantly destroy each other) are near the event horizon. Then the virtual particle pair gets divided: one disappears in the black hole (and its quantum mechanical information) and the other one becomes real. Thus the black hole radiates but unfortunately this radiation is so low that astronomical observations are nearly impossible.
Therefore scientists have to simulate black holes to get empirical evidence. The physicist Jeff Steinhauer of the Technion, the University of Technology of Haifa in Israel exactly did this. He realized an idea of physicist Bill Unruh with an acoustical event horizon. He uses a fog made of rubidium atoms which is only slightly above the absolute zero. Because they are trapped inside an electromagnetic field these atoms become a Bose-Einstein Condensate. Inside of this condensate the acoustic velocity is only a half millimeter per second. With the help of accelerating some above this speed an artificial event horizon is created. The low temperatures lead to quantum fluctuations: pairs of phonons develop. In the simulation these pairs also get divided: one gets caught by the supersonic event horizon; the other one becomes some kind of Hawking radiation.
It is still not sure if this experiment really simulates black holes. According to Ulf Leonhardt it does not proof for sure that the two phonons are entangled. Thus it is not sure if the pairs arised out of one fluctuation. Leonhardt even doubts that the fog of atoms is a real Bose-Einstein Condensate. Leonard Susskind thinks this experiment does not reveal the mysteries of black holes: for instance it does not explain the information paradox, because acoustic black holes do not destroy information.

Scientists observe liquid with 'negative mass', which turns physics completely upside down

Scientists have created a material with “negative mass”, apparently upending our entire understanding of physics.

Negative mass works exactly as it sounds, and in a way that seems impossible: when you push it, it goes entirely in the other direction.

Normally, things accelerate in the direction they are pushed, in line with Isaac Newton’s second law of motion. But in the case of the new liquid, it pushes in the opposite direction.

There’s nothing necessarily meaning that everything has to have positive mass, and it can in fact go both ways like electric current or magnets.

The strange material was created by Michael Forbes, a physicist at Washington State University, and his team. They did it by cooling down rubidium atoms so that they were just ever so slightly above absolute zero – creating a what’s called a Bose-Einstein condensate and creating all sorts of bizarre physical effects.

In such a state, particles start to move incredibly slowly and act like waves. They can also move in unison, flowing without using up any energy.

Scientists then use laters to kick the atoms around, switching them up and changing the way they spin. When that happens, their usual behaviour is turned inside out – if the bowl the particles are sitting in was broken, they’d expect to rush out, but they do the opposite.

“Once you push, it accelerates backwards,” said Forbes, who acted as a theorist analysing the system. “It looks like the rubidium hits an invisible wall.”

Because scientists have such control over the unusual substance, they can use it to explore places in the universe where similar effects seem to happen. In time, the findings could be used to study experiments in astrophysics, like neutron stars, and cosmological phenomena like black holes and dark energy, where it’s not possible to do experiments.

anonymous asked:

Can you talk about the Bose Einstein Condensate?

Bose-Einstein condensate is a state of matter where atoms are cooled to very very near absolute zero and because they have so little potential energy and are hardly moving relatively to each other, they start to form clumps where groups of atoms behave as if they were single atoms.

  • Me: I'm gonna get through this whole damn period while being the chillest bitch on the planet
  • INTJ BF: What temperature are you? -273.14 Celsius?
  • Me: Even if I was you're still so hot you could melt me
  • INTJ BF: Nah you would behave like a superfluid with 0 viscosity and 0 entropy. Like a Bose-Einstein condensate.
  • Me: I'm trying to flirt with you stopppppp
  • INTJ BF: I'm flirting too
Cognitive Functions as Physics Disciplines: The Judging Functions

Originally posted by commie-pinko-liberal

Ti: Condensed Matter Physics

Condensed Matter Physics is weird. It’s nominally the study of the physical properties of non-gas phases of matter but actually it ends up being the intersection of a number of systems. It’s currently the most widely-studied topics in contemporary physics (about a third of active American physicists) but not always that well understood. Hot topics include superconductors, new states of matter (like the always-fascinating Bose-Einstein Condensate), and symmetry breaking. Pretty much take any other physics subspecialty on this list, and you can find a way, as a condensed matter physicist, to somehow get involved in it. It also notably has both theoretical and experimental opportunities, so both the STPs and NTPs have something to do.

Originally posted by fuckyeahfluiddynamics

Te: Medical and Biophysics

The application of physics to biology. Medical physics is the study of the physics used in medicine (such as radiation therapy or the science of MRI), and biophysics is broader and includes the kinetics of biological systems, the electronics of the brain, and essentially filling in the gaps of what cannot be explained by traditional biology or chemistry in the processes of living organisms. Both these fields tend towards problem-solving: how to use radiation, magnetism, kinetics, and so forth to our advantage in working with biological systems. Both also tend strongly towards experimentation/observation over theory, and while, like condensed matter physics, the fields are very interdisciplinary, they’re a little more utilitarian, rather than all-encompassing, as they pull from other areas.

Originally posted by amanda-future-doctor

Fi: Astrophysics/Cosmology

Walt Whitman may not have been a fan of the science, but everyone wants to write poetry about the stars sometimes. Case in point:

“It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known.”  - Sagan (aka the guy who did the original Cosmos, also smoked a lot of weed). While a lot of astrophysics and cosmology is cold hard analysis/coding of gravitational lensing and spectra, and astrobiology

is its own weird subdiscipline that often falls under geology in academia, astrophysics and cosmology are ultimately the product of the denizens of the universe trying to discover where we came from.

Originally posted by cosmosondrugs

Fe: Classical Physics (Mechanics, E/M, Thermo, Optics, and Acoustics)

This is where it all began. It may seem basic now, but without this shared groundwork, none of the other disciplines I’ve mentioned would be remotely possible. It’s also not dead by any means. Fluid dynamics operates under mechanics (there’s no significant quantum physics or relativity involved) but we still don’t fully understand turbulence. The three-body problem, a classical mechanics (gravitation) problem, has no single analytical solution so we must make approximations based on empirical evidence. And without classical physics, there’s also literally no engineering. This is what holds it all together, and it’s what almost everyone can reference. It’s also a great introduction to physics: you can recreate a lot of Galileo’s experiments, for example, at home. You can sass your parents about how leaving the door open doesn’t in fact let the cold air in, but rather the hot air out*.

Originally posted by m0onbby

*thermodynamically this is true; since there’s often wind, the cold air is likely not stationary and therefore can enter your house. And in the end the temperature of your house drops, so ultimately your parents are right in spirit if not in the technicalities.

zodiac elements EXPLAINED

aries: sodium - because aries is THE fire sign, and sodium reacts explosively and violently with water. i wasnt 100% sure about it. i was on the fence with hydrogen, because it’s ALSO a very explosive element

taurus: iridium - because iridium is one of the most resistant metals, one of the densest, and strongest elements out there. taurus is described as being stable and also impossibly stubborn

gemini: hydrogen - since hydrogen is the most abundant, and at times dangerous and unpredictable, and gemini is unpredictable at times, and all over the place, like how hydrogen is constantly combining to form new substances

cancer: tungsten - because it, like iridium, is a very tough element. cancer is described as having a really tough persona that’s hard to get through and can take a lot of shit before cracking. tungsten is one of the hardest elements, and has the highest melting point.

leo: magnesium - i dont like this one. i couldnt decide. i was torn between hydrogen and oxygen too. but i chose magnesium because when ignited, it burns extremely bright (reminiscent of the the sun, the ruling planet of leo), it’s also used in fireworks, and leo is also known as the performer.

virgo: iron - i was also unsure abt this. but virgos are described as being workaholics. iron, in mostly all living creatures, is used to transport oxygen. it’s never stationary. in a more worldly sense, virgos are also described as keeping their core identity throughout their lives, and the core of earth is solid iron

libra: carbon - this was the easiest. libras are the easiest to get along with other people, are always trying to find balance. carbon is the most versatile element, combines to form all organic compounds, and can combine in hundreds, thousands of ways to produce stable compounds

scorpio: uranium - incredibly stubborn, does its own thing all the time, and if used correctly, can be incredibly useful. if used incorrectly, can become the most dangerous weapon of the century. scorpio is the same way. supposedly if you cross a scorpio, you’re going to remember it for years to come.

sagittarius: nitrogen - because they are free-spirited, hard to pin down to other individuals. nitrogen occurs mostly in the atmosphere and most organisms can’t use pure nitrogen as it occurs in the atmosphere, and even after years of evolution, most still aren’t equipped to break down nitrogen for their uses.

capricorn: polonium - capricorn is described as being a loner, which is exactly what polonium is. it’s radioactive, and has no known stable isotopes. also, capricorns are described as being hardworking toward their goals. it took marie curie many fruitless tries to isolate pure polonium.

aquarius: silicon - water bearers are innovators. they’re known for exporting their ideas and building new inventions, having new ideas, and bringing the world into new ages. silicon, being found in clay and stone and mortar, is used for literally building cities. more refined silicon is used in the electronics industry, and literally brought us into the digital age.

pisces: rubidium - i was also on the fence with this. pisces are considered to be easily impressionable, and rubidium is an incredibly ductile element. pisces are also considered to be very open and receptive, and rubidium is a highly reactive and spontaneously combusts in open air. pisces, being the last sign, is also symbolic for looking into the unknown. rubidium was the first element to get so close to absolute zero, that it created an entirely new and little known or understood state of matter called a bose-einstein condensate.

Out of curiosity, I googled the physicist behind the Bose part in Bose-Einstein statistics, since he also has a type of particle named after him. Turns out, he was an Indian polyglot and knew Saha (as in the guy behind the Saha equation), who was also Indian. Fun fact: Bose sent his paper to Einstein, even though he didn’t know Einstein. Einstein recognised its importance, translated the paper into German and got it published in a German physics journal for Bose. Dirac later named Bosons after him. I love this so much because a) there were probably as many significant Indian physicists alive at the same time when there was a significant number of German and American physicists who don’t get talked about nearly enough and b) physicists helping and acknowledging other physicists is one of my favourite things because it reminds me that all physicists aren’t assholes 

anonymous asked:

I just saw a small post on tumblr about a woman, Lene Hau, who managed to stop light completely in 2001, how is that possible? how do you stop light? I tried reading about her, but it was all too complicated to understand

Yes, that’s mad science if I’ve heard of it. Very very cool.

I don’t know the technical details of how you do this but I know the gist:

Light moves through a vacuum at a constant speed of about 300,000 km/h.

When light goes through a different medium however it slows down. It slows down a lot in really dense mediums (technically in mediums with high a “high index of refraction” actually but density works for this).

Now, when something cools down it contracts (gets more dense). When it heats up, it expands (less dense). Lene Hau used lasers to cool down sodium molecules to such a ridiculous degree that it became a phase of matter called a Bose-Einstein condensate where the sodium molecules basically became more cold than anywhere else in the universe (told you this was… cool).

When light is passed through a BEC it slows incredibly. Somehow Lene was able to halt it completely within the sodium.

Artificial intelligence replaces physicists

Physicists are putting themselves out of a job, using artificial intelligence to run a complex experiment.

The experiment, developed by physicists from The Australian National University (ANU) and UNSW ADFA, created an extremely cold gas trapped in a laser beam, known as a Bose-Einstein condensate, replicating the experiment that won the 2001 Nobel Prize.

“I didn’t expect the machine could learn to do the experiment itself, from scratch, in under an hour,” said co-lead researcher Paul Wigley from the ANU Research School of Physics and Engineering.

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