Why Empty Space Isn’t Empty

New Scientist has a nice little video explaining that vacuums, empty space, aren’t really empty. You, my dear reader, already know that from reading about the big laser that will tear apart virtual particles, and the recent experiment that materialized virtual photons, but you should check this short video out if you’re interested (can’t embed the video here, sadly). 

They also link to a full-length article discussing how the theory of the vacuum has evolved over time, which it looks like you’ll have to register (for free) to read. I won’t go into all of it, but in essence it portrays a somewhat philosophical struggle over the millennia about how emptiness could be empty, which led to and away from the idea of a luminiferous aether filling everything, and finally to quantum mechanics.

Now we know that because of the quantum uncertainty involved at the smallest scales, there are always fluctuations of fields and particles in a vacuum, meaning that any vacuum does indeed have energy in it. There’s never nothing. Is that reassuring? I think a constantly fluctuating space is much more interesting than a giant, vast emptiness. 


Creating Light From a Vacuum

Quantum theory predicts that in a vacuum, virtual particles are constantly being created in pairs and then quickly destroying each other. Up until now, outside of theory there hasn’t been any proof that they actually exist. Now, researchers have managed to make some of these particles materialize: by giving energy to virtual photons, they created “real”, measurable photons. Did they say “Let there be light!” as they did it? Let’s just pretend so. 

From ScienceDaily:

Chalmers scientist, Christopher Wilson and his co-workers have succeeded in getting photons to leave their virtual state and become real photons, i.e. measurable light. The physicist Moore predicted way back in 1970 that this should happen if the virtual photons are allowed to bounce off a mirror that is moving at a speed that is almost as high as the speed of light. The phenomenon, known as the dynamical Casimir effect, has now been observed for the first time in a brilliant experiment conducted by the Chalmers scientists.

“Since it’s not possible to get a mirror to move fast enough, we’ve developed another method for achieving the same effect,” explains Per Delsing, Professor of Experimental Physics at Chalmers…

The “mirror” consists of a quantum electronic component referred to as a SQUID (Superconducting quantum interference device), which is extremely sensitive to magnetic fields. By changing the direction of the magnetic field several billions of times a second the scientists were able to make the “mirror” vibrate at a speed of up to 25 percent of the speed of light.

“The result was that photons appeared in pairs from the vacuum, which we were able to measure in the form of microwave radiation,” says Per Delsing. “We were also able to establish that the radiation had precisely the same properties that quantum theory says it should have when photons appear in pairs in this way.”

What happens during the experiment is that the “mirror” transfers some of its kinetic energy to virtual photons, which helps them to materialise. According to quantum mechanics, there are many different types of virtual particles in vacuum, as mentioned earlier. Göran Johansson, Associate Professor of Theoretical Physics, explains that the reason why photons appear in the experiment is that they lack mass.

“Relatively little energy is therefore required in order to excite them out of their virtual state. In principle, one could also create other particles from vacuum, such as electrons or protons, but that would require a lot more energy.”

That’s crazy. What’s the wear and tear like on something vibrating at 25% the speed of light? It’s unimaginable. Whoever engineered that must’ve had an incredibly difficult time.

I was torn about posting this article since on the one hand it sounds awesome, but on the other hand it’s definitely over my head, so I can’t exactly help break it down for you any more than they already did. Anyway, it’s clear at least that this is a very cool experiment and very big news for physics, so let’s bask in this moment of awesome. Are you basking? Bask!

Big Science and a Big Laser

Scientific research is generally rather expensive and requires specialized equipment and real estate, but some projects are bigger than others. Physics World has a pdf of a supplement to their magazine describing a few giant-sized physics facilities currently working (like the LHC at CERN) or in the works; it’s pretty interesting to look over and see the huge ambition at play, and the frontiers of science. 

One of the proposed projects, the Extreme Light Infrastructure Ultra-High Field Facility, is the subject of a Telegraph article today. It’s going to include the most powerful laser in the world by orders of magnitude, strong enough to tear apart the virtual particles that are theorized to appear and disappear in a vacuum, and thus be able to learn more about them.

From the Telegraph:

Contrary to popular belief, a vacuum is not devoid of material but in fact fizzles with tiny mysterious particles that pop in and out of existence, but at speeds so fast that no one has been able to prove they exist.

The Extreme Light Infrastructure Ultra-High Field Facility would produce a laser so intense that scientists say it would allow them to reveal these particles for the first time by pulling this vacuum “fabric” apart.

They also believe it could even allow them to prove whether extra-dimensions exist.

“This laser will be 200 times more powerful than the most powerful lasers that currently exist,” said Professor John Collier, a scientific leader for the ELI project and director of the Central Laser Facility at the Rutherford Appleton Laboratory in Didcot, Oxfordshire…

The ELI Ultra-High Field laser is due to be complete by the end of the decade and will cost an estimated £1 billion. Although the location for the facility will not be decided until next year, the UK is among several European countries in the running to host it…

The Ultra-High Field laser will be made up of 10 beams, each twice as powerful as the prototype lasers, allowing it to produce 200 petawatts of power – more than 100,000 times the power of the world’s combined electricity production – for less than a trillionth of a second…

It will cause the mysterious particles of matter and antimatter thought to make up a vacuum to be pulled apart, allowing scientists to detect the tiny electrical charges they produce.

These “ghost particles”, as they are known, normally annihilate one another as soon as they appear, but by using the laser to pull them apart, physicists believe they will be able to detect them.

Cool. It’s funny to think that the solution to the most subtle universal mysteries are solved by building giant crazy lasers and shooting stuff – it sounds like a solution from the mind of a 12-year-old boy. Or look at supercolliders like the LHC, where the solution instead is to smash particles together really really hard. Then again, those are descriptions tailored for mass consumption, so they leave out the 99.99% of the work that’s not quite so exciting – but still, at least parts of it are pretty exciting. 

If you looked at the supplement about “big science” from Physics World, you may have noticed that all of the projects they discuss are mainly or entirely European, which is kind of disappointing. It should be clear why science can be damn expensive, but if our continent doesn’t step its game up it looks like it’s going to fall behind, at least in this realm.

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