Category: quantum

Even In A Quantum Universe, Space And Time Might Be Continuous, Not Discrete

“In General Relativity, matter and energy tell space how to curve, while curved space tells matter and energy how to move. But in General Relativity, space and time are continuous and non-quantized. All the other forces are known to be quantum in nature, and require a quantum description to match reality. We assume and suspect that gravitation is fundamentally quantum, too, but we aren’t sure. Furthermore, if gravity is ultimately quantum, we don’t know whether space and time remain continuous, or whether they become fundamentally discrete.

Quantum doesn’t necessarily mean that every property breaks down into an indivisible chunk. In conventional quantum field theory, spacetime is the stage upon which the various quanta act out the play of the Universe. At the core of it all should be a quantum theory of gravity. Until we can determine whether space and time are discrete, continuous, or unavoidably blurred, we cannot know our Universe’s nature at a fundamental level.”

If you could look at the Universe down to the smallest possible scales, fundamentally, what would you find? Would you discover that space and time really could be broken up into tiny, indivisible entities where the was a length scale and a timescale that could be divided no further? Would you discover that space and time were quantum in nature, but were instead a continuous fabric? Or would you discover something else, like that space and time weren’t quantum or that there was a fundamental “blurring” that prevented you from seeing below a specific scale?

Quantum, surprisingly to many, doesn’t necessarily mean it can be broken up into indivisible chunks. Space and time might not be discrete even if they’re quantum. Time to learn the difference.

This One Experiment Reveals More About Reality Than Any Quantum Interpretation Ever Will

“So you fire a beam of electrons at a barrier with two slits in it, and look at where the electrons arrive on the screen behind it. Although you might have expected the same result you got for the pebble-experiment earlier, you don’t get it. Instead, the electrons distinctly and unambiguously leave an interference pattern on the screen. Somehow, the electrons are acting like waves.

What’s going on? Are these electrons interfering with each other? To find out, we can change the experiment again; instead of firing a beam of electrons, we can send one electron through at a time. And then another. And then another. And then another, until we’ve sent thousands or even millions of electrons through. When we finally look at the screen, what do we see? The same interference pattern. Not only are the electrons acting like waves, but each individual electron behaves as a wave, and somehow manages to create an interference pattern only by interacting with itself.”

It’s been around for more than 200 years, but the double-slit experiment remains one of the best concrete ways to probe the quantum nature of reality. By tinkering with the apparatus and how it’s set up, you can determine how nature behaves under a wide variety of conditions, and wow, is it ever surprising and unintuitive. Instead of arguing over unanswerables like which philosophical interpretation is most pleasing, why not look at something real? 

These are the questions we’re actually answering, and you won’t find anything more profound than the answers that nature provides us with.

Photo

Photo

Photo

Friend: Is your cat alive?

Schrödinger:

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?

“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?

“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!