## How NOT to destroy the Earth with a coffee can

Heh, I bet a lot of you folks bought it, didn't you?

After all it's written in an HTDTE-stylee, it's clearly aimed at the same audience, it even steals the whole article title for its nefarious purposes. But you know what's happened? The author has upped the "humour" level and subtracted scientific accuracy to compensate.

It's baloney!

It's based on THIS, an article I wrote for LiveScience, an article which is now long superseded and obsolete. In particular, the method cited (#6, destroyed by vacuum energy) was long been known to be garbage.

This entire method hinges on a single highly spurious "fact": "The vacuum of... a space as small as a light bulb generates enough energy to boil all of the Earth's oceans."

UNTRUE, SIR.

In general physics, it's sensible to assume that the lowest amount of energy a system can have is zero. For example, if you're doing classical mechanics, you assume that "everything is motionless sitting on the ground" would be a situation with zero energy. If you're doing thermodynamics, you assume that the coldest temperature an object can be, which turns out to be -273.18 degrees Celsius, is "absolute zero". (Hence the Kelvin temperature scale, which actually starts at zero Kelvins.)

However, in quantum mechanics you often find that the lowest amount of energy a system have, which is called the zero-point energy, is not zero. In particular, the zero-point energy of any given point in vacuum - the vacuum energy - is positive. This has actually been proved in experiments. Vacuum is not "empty space". It has energy.

And, in theory, because every point in space has a positive amount of energy, that means any finite volume of space, which would contain an infinite number of points, would also contain an infinite amount of vacuum energy. Even if we assume that a "point" has a nonzero volume (which seems probable, given current quantum mechanical theories), there's still more than enough energy to make vacuum energy potentially the most abundant energy source of any kind, ever, and give rise to the "boil all the oceans" factoid above.

That is, unless you do your mathematics properly.

When you were learning science in high school you may have noticed that the science you were taught each year seemingly contradicted the science you were taught the previous year. For example, when you're just starting out you're usually taught that thermal energy and sound energy and kinetic energy are different types of energy. But later on it actually turns out that they're all aspects of the same mighty deity which is called things moving.

This can be increasingly frustrating for people who find it difficult to unlearn things they've already learned, but it is necessary to the educational process for two reasons. First of all, you just can't understand the "real situation" when you're 15 years old. Most of science tends to boil down to very unpleasant, hardcore mathematics which no kid can grasp. Slowly replacing old ideas with new ones is actually much easier than teaching the "truth" right away.

The second reason is that if you got every scientist in the world together and asked them, "When you start right at the most basic principles of physics, how does the universe work? What is the ultimate truth?", they would reply, "We don't know."

Because we don't.

We don't have all the answers yet. We haven't got to the bottom yet. We are still digging. There are still unsolved problems. All scientists are still in the same situation that you were in - a continuous cycle of forming theories, finding evidence to support or contradict the theories, and using the evidence to form new, more complex and refined theories. They're just a lot further down the road than you were.

And this vacuum energy thing is actually a very typical example of a question in science to which we do not yet know the answer. You see, right now there are two big theories in physics. One of these is quantum mechanics, which is a stunningly beautiful and powerful theory which explains how very tiny fundamental particles - atoms and smaller - interact with each other at very small scales. The other is general relativity, which explains how gravity is actually a curve in spacetime, and generally works on very large scales.

Both these theories work wonderfully in their respective "domains", but the problem is, they don't meet in the middle. Quantum mechanics predicts one thing while general relativity predicts another. As a pertinent example, a naive formulation of the equations of quantum mechanics gives the preposterously large vacuum energy figure described in that "coffee can" article. Whereas a direct measurement of the energy density of actual space gives a much more likely-to-be-accurate figure of about 1 joule per cubic kilometre.

With that, the whole thing is scuppered. Either because quantum mechanics doesn't factor in anything to do with gravity, or because something's wrong with general relativity, or because something's wrong with how we set up the problem, there is, unfortunately, no bottomless well of energy to be tapped here. Somehow, somewhere, the mathematics is wrong. One day, a Grand Unified Theory which knots together both quantum mechanics and general relativity will be discovered, and we can put this messy, confusing business behind us. In the meantime, use common sense!

I don't even have to bother debunking the considerably more glaring errors with the coffee can method, such as:

1. Coffee cans are not transparent, so subatomic particles inside the coffee can would be unable to see the picture of Angelina Jolie.

2. Subatomic particles are smaller than any visible wavelength of light, meaning they would be incapable of coherently perceiving any kind of ordinary photographic image; you'd need to make a picture out of very high-frequency radio waves or something, which is impossible.

3. "Being hit by a photon of electromagnetic energy" itself constitutes a particle interaction, so it is physically impossible for a given subatomic particle to be hit by the thousands or millions of photons which would be necessary to make sense of the image before it collides with a subatomic antiparticle and ceases to exist.

4. Most subatomic particles are heterosexual females who would be far more distracted by a snap of, for example, George Clooney.

I mean. Come on, guys.

Up next: how to cause the Earth to cease to exist by selectively collapsing its quantum waveform!