Category: quantum

Yes, Virtual Particles Can Have Real, Observab…

Yes, Virtual Particles Can Have Real, Observable Effects

“Now that the effect of vacuum birefringence has been observed — and by association, the physical impact of the virtual particles in the quantum vacuum — we can attempt to confirm it even further with more precise quantitative measurements. The way to do that is to measure RX J1856.5-3754 in the X-rays, and measuring the polarization of X-ray light.

While we don’t have a space telescope capable of measuring X-ray polarization right now, one of them is in the works: the ESA’s Athena mission. Unlike the ~15% polarization observed by the VLT in the wavelengths it probes, X-rays should be fully polarized, displaying right around an 100% effect. Athena is currently slated for launch in 2028, and could deliver this confirmation for not just one but many neutron stars. It’s another victory for the unintuitive, but undeniably fascinating, quantum Universe.”

If you think about empty space at a quantum level, you’ll find that it isn’t so empty, after all. Due to the inherent effects of quantum uncertainty, particle/antiparticle pairs pop into and out of existence continuously, including electrically charged particles. If you look at the quantum vacuum in the presence of a strong enough external magnetic field, the positive and negative particles, even though they’re only virtual particles, will move differently, and therefore will affect the real particles that pass through them differently than if there were no magnetic field. This leads to a real, observable signal that can be seen in space: around neutron stars! 

Heisenberg first predicted this in 1936, and today, we know it’s true. Get the story of the first observable effect of vacuum birefringence today.

Ask Ethan: What Is An Electron?

Ask Ethan: What Is An Electron?

“Please will you describe the electron… explaining what it is, and why it moves the way it does when it interacts with a positron. If you’d also like to explain why it moves the way that it does in an electric field, a magnetic field, and a gravitational field, that would be nice. An explanation of charge would be nice too, and an explanation of why the electron has mass.”

When we, as physicists, speak about fundamental particles, we refer to the smallest constituents of matter and energy that cannot be divided any farther. There are two classes of such particles, fermions (which can be matter or antimatter) and bosons (which are neither), and they behave in rather unintuitive ways, since they’re quantum in nature. But even though there are many properties of quantum particles that are inherently uncertain, there are some that are intrinsic and perfectly well-known. These are the properties that define each type of particle and allow us to discern them from all others.

Here is, to the best of our knowledge, what the electron truly is, along with some fundamental questions we still have yet to answer about them!

Ask Ethan: What Is An Electron?

Ask Ethan: What Is An Electron?

“Please will you describe the electron… explaining what it is, and why it moves the way it does when it interacts with a positron. If you’d also like to explain why it moves the way that it does in an electric field, a magnetic field, and a gravitational field, that would be nice. An explanation of charge would be nice too, and an explanation of why the electron has mass.”

When we, as physicists, speak about fundamental particles, we refer to the smallest constituents of matter and energy that cannot be divided any farther. There are two classes of such particles, fermions (which can be matter or antimatter) and bosons (which are neither), and they behave in rather unintuitive ways, since they’re quantum in nature. But even though there are many properties of quantum particles that are inherently uncertain, there are some that are intrinsic and perfectly well-known. These are the properties that define each type of particle and allow us to discern them from all others.

Here is, to the best of our knowledge, what the electron truly is, along with some fundamental questions we still have yet to answer about them!

No, Quantum Tunneling Didn’t Break The S…

No, Quantum Tunneling Didn’t Break The Speed Of Light; Nothing Does

“You might think, based on what you just read about the speed of quantum tunneling being instantaneous, that this means that particles can travel infinitely fast, breaking the speed of light, through a quantum mechanical barrier of finite, non-zero thickness. That’s the misinterpretation that always crops up, and how people fool themselves (and unscrupulous news organizations try to fool you) into thinking they’re breaking the speed of light.

But all that’s happening here is a portion of the quantum particles found in the pulse tunnels through the barrier, while the majority of the particles does what tennis balls do: they bounce back, failing to arrive at the destination. If you can front-load which particles make it through the barrier, preferentially cutting off the particles in the back of the pulse, you’ll falsely measure a faster-than-light speed, even though no individual particle actually breaks the speed of light.”

For the first time, researchers have measured what the speed of quantum tunneling is, and found that it was consistent with an instantaneous transition. If you’re in a quantum configuration that keeps you bound, or on one side of a barrier, tunneling can enable you to become unbound, or arrive on the other side of the barrier. But that doesn’t mean you can physically travel a finite distance through that barrier instantaneously, or faster-than-light. You can’t.

Here’s the real story, with an extra bonus of how this story (and ones like it) get mis-reported all the time.

Ask Ethan: How Does Quantum Physics Make Levit…

Ask Ethan: How Does Quantum Physics Make Levitation Possible?

“I am fascinated about superconductivity and its associated Meissner effect it creates. From what I understand, the Meissner effect (when the magnetic field is expelled and levitation occurs) is created when there is zero electrical resistance. […] Is zero electrical resistance free flowing electrons? […] What actually causes the expulsion of the magnetic field that creates levitation?”

Imagine the following science-fiction scenario: you hop into a vehicle and accelerate up to cruising speed. All of a sudden, you push a button and you lift up off the road, levitating over it. You take your foot off the gas and the steering wheel, and instead of slowing down or losing control, you remain moving at a constant speed, following all the twists-and-turns of the road effortlessly.

It sounds like a crazy scenario, but there’s a quantum phenomenon that allows you to do exactly this: superconductivity! With the right type of superconductor and a properly-configured magnetic track, we can already make this a reality at liquid nitrogen temperatures.

How does it happen, and what will it take to turn this science-fiction dream into a reality? Get the answer today!

Ask Ethan: Are Quantum Fields Real? “I would …

Ask Ethan: Are Quantum Fields Real?

“I would be very interested in a post about quantum fields. Are they generally/universally believed to be real and the most fundamental aspect of our universe or just a mathematical construct? I’ve read that there are 24 fundamental quantum fields: 12 fields for fermions and 12 for bosons. But I’ve also read about quantum fields for atoms, molecules, etc. How does that work? Does everything emerge from these 24 fields and their interactions?”

When you think about the Universe, you probably think about it in a very particular fashion. There’s spacetime: the backdrop upon which the matter in the Universe exists, and then there are particles and antiparticles, which make up everything we can conceive of in the cosmos. Only, the quantum nature of reality is very different from this intuitive picture, and quantum field theory goes a few steps farther than even the unintuitive pictures we have in our heads. What if Heisenberg uncertainty, the Pauli exclusion principle, wave-particle duality and more were all just manifestations of something very basic: quantum fields themselves?

Quantum fields, believe it or not, are the most real thing we know of in the Universe. Here’s the science of how they make up our Universe.

Regular

Note on Electron level transitions

You might have seen animations like this that show an electron undergoing a transition from a lower energy to a higher energy state and vice versa like so:

image

There is something really important about this image that one must  understand clearly.

The diagram represents the transition in energy of an electron BUT this does not mean that the electron
is magically jumping from one position and respawning at another
position.

image

                        The electron’s position is NOT doing this i

If you want to know about the probability of finding an electron around the nucleus at a certain energy level, you look at its wavefunction and not at the energy diagram.

Here is the wavefunction of a hydrogen atom and each stationary state defines a specific energy
level of the atom.

image

This might not sound like a big deal but one might be surprised to know that there are a lot of people who think that the electron is magically transported from energy level to another which most certainly is not true.

Have a good one!

– A2A

Ask Ethan: Could Dark Matter Not Be A Particle…

Ask Ethan: Could Dark Matter Not Be A Particle At All?

“If dark energy can be interpreted as an energy inherent to the fabric of space itself, could it also be possible that what we perceive as “dark matter” is also an inherent function of space itself – either tightly or loosely coupled to dark energy? That is, instead of dark matter being particulate, could it permeate all of space with (homogeneous or heterogeneous) gravitational effects that would explain our observations – more of a “dark mass”?”

When it comes to all the matter and radiation in the Universe that we know of, at a fundamental level, every bit of it is made out of particles. From photons to neutrinos to leptons and quarks, there’s a quantum of energy for every type of energy we know of. Except, that is, for dark energy, which appears to be inherent to space itself, and doesn’t have a particle counterpart. There’s no evidence for clumping, inhomogeneities, or changes in dark energy over time. Well, what about dark matter, then? Is it possible that the most elusive form of mass in our Universe isn’t a particle at all, but rather can be interpreted as some sort of function inherent to space itself? While it does need to clump, and drives the formation of galaxies and the other structure in the Universe, it doesn’t necessarily need to be particle-based in nature.

It could, in fact, behave as a perfect cosmological fluid! What are the alternatives, constraints, and how do we know? Find out on this week’s Ask Ethan!

In A Quantum Universe, Even Mass Is Uncertain …

In A Quantum Universe, Even Mass Is Uncertain

“It’s one of the most remarkable and counterintuitive results of the quantum Universe, that every unstable particle that you make has an inherent uncertainty to the most seemingly fundamental property of all: mass. You can know what the average mass of a typical particle of any particular type, and you can measure its width, which is directly related to its mean lifetime through the Heisenberg uncertainty principle. But every time you create one new particle, there’s no way to know what its actual mass will be; all you can do is calculate the probabilities of having a varieties of masses. In order to know for sure, all you can do is measure what comes out and reconstruct what actually existed. Quantum uncertainty, first seen for position and momentum, can now be convincingly stated to extend all the way to the rest energy of a fundamental particle. In a quantum Universe, even mass itself isn’t set in stone.”

There are a few properties you can say intrinsically belong to a particle: things like mass, spin, electric charge, and certain other quantum numbers. If your particle is completely stable for all eternity, there’s no reason to question any of this. But if a particle you create, even a fundamental one, has an inherent instability and can decay, all of a sudden Heisenberg comes in to mess everything up! Suddenly, the fact that you have an uncertain lifetime means you have that pesky energy-time uncertainty, and the energy of your particle is intrinsically uncertain, too. Because E = mc^2, that means your mass is uncertain, too. And the shorter-lived your particle is, on average, the more uncertain your mass is. This means when you make a top quark, for example, it could have a mass of 165 GeV, 170 GeV, 175 GeV, 180 GeV, or anywhere in between those values. (Including some values outside of that range!)

In a quantum Universe, even mass is uncertain. Here’s the fundamental physics story of how that came to be, both theoretically and experimentally.