Vacuum Energy, Dark Energy and Richard Dawkins

Yesterday in my homeschool science class, we had a discussion of how dark energy is thought to drive the expansion of the universe.

“If you had a bottle one cubic centimeter in volume and sucked out everything in it: every atom, molecule, dark matter particle… everything… how much energy do you think would remain in the bottle?”

“Zero”, everyone replied.

That’s a sensible answer, if we remove all matter and energy that exists in a volume, it is natural to assume that there is no energy left in the bottle.

But you’d be wrong if you did that.

There is roughly 10^(-8) ergs (I’ve written before about how big an erg is) of energy in the bottle. Admittedly, that’s a small amount of energy, but there is nothing in physics that says that the amount of energy in empty space has to be zero.

That energy is what is known as vacuum energy and cosmologists think this is the “dark” energy that is driving the expansion (and acceleration) of the universe. 70% of the universe is thought to be made of this energy.

How do we know it’s there?

If dark energy is there, it:

• causes the universe to accelerate
• contributes to the shape of the universe, in this case, making it flat

Cosmologists have measured the shape of the entire universe by mapping the cosmic microwave background and found the universe to be flat. There isn’t enough matter in the universe, either normal or dark, to account for this, there must be something else pushing the universe into a pancake.

That something else is dark energy, the empty space between particles of normal matter exerts a force on everything around it (10^-8 ergs per cubic centimeter), pushing against the fabric of spacetime, stretching the universe outward.

Further, recent measurements of supernovae in distant galaxies have confirmed that the universe is accelerating.

Dark energy is a strange concept, one that is difficult to accept because it’s so counter-intuitive, yet observations confirm its existence.

One final note about dark energy: it is a constant throughout the universe. It is 10^-8 ergs per cubic centimeter everywhere. The amount of normal matter in the universe, on the other hand, is NOT constant, it gradually disappears as the universe expands (e.g., getting swallowed up in black holes), ultimately leaving nothing but dark energy behind.

These kids are pretty sharp, they ask good questions and really enjoy thinking about these issues. The excitement and energy in the room was palpable, at the end of the class, everyone was talking excitedly and pacing all over the room, arms flailing as they discussed these ideas and understanding dawned on them.

You’d have thought it was a revival meeting (no speaking in tongues though, unless you count the physics jargon).

We were able to discuss a seemingly absurd idea, that there is energy in nothing, and by looking at the evidence and verifiability of the idea, reach a conclusion, based on the evidence, that dark energy exists.

And you know the best part?

We were able to do this without invoking a designer, God, or Jebus on a dinosaur, which is my…

Segue into my bit about Richard Dawkins:

I was reading this opinion article from Lawrence Krauss where he was attempting to understand the usefulness of Richard Dawkins’ call for atheists to ‘come out’ and let our voices be heard against the din of religion.

We also get cool t-shirts with a big “A” on them, although I like these better.

I really admire Richard Dawkins, but I’m afraid I agree with Krauss (who also has great respect for him):

what on earth does Dawkins think his latest campaign will achieve? It seems to me to be as ill-advised as attempting to label atheists as “brights” – with its implication that those who are not atheists are dumb. Dawkins has a great record of using sound intellectual arguments to try to convince the faithful to abandon their faith and persuade non-believers to be open about their scepticism. But before embarking on this new effort to appeal to people’s emotions, he might have been well advised to consult a public relations firm. The scarlet A is strongly reminiscent of the A for “adulterer” in Nathaniel Hawthorne’s classic novel The Scarlet Letter. I don’t know who thought that this, combined with the phrase “coming out” with its gay connotations, and references to a “Jewish lobby”, would win hearts and minds in middle America, but I can’t imagine that it will.

Using my last class discussion as a backdrop, it occurs to me that instead of whooping and hollering at the top of my lungs about how great atheism is, I think I can come ‘OUT’ more effectively as a teacher. The last thing we atheists should be doing is behaving like a bunch of evangelists.

My students and I were able to discuss the nature of the entire universe, marvel at its beauty and rationally understand how it works, without ONCE mentioning anything about religion. It just never came up, it would have been absurd to even talk about God in the context of dark energy. I’m teaching four kids to ask questions, be skeptical, and think for themselves. Don’t take anyone’s word for anything, find out for yourself.

And it turned out to be quite emotional, these kids were happy and excited.

People have complained to me that atheism is emotionless, I disagree. Again from Krauss:

atheism finds itself at a serious disadvantage compared with the world’s organised religions. There are several reasons for this, but included among them, I would argue, are atheism’s lack of deep emotional symbols, lack of a celebratory mythos based on oppression and discord, and lack of a sense of exclusiveness based upon a “holier than thou” approach to life. (full article)

I feel like I do have deep emotional symbols and they come in the form of an intellectual understanding of my world. It’s what led me to become an astronomer in the first place. For me, there is no better feeling, no greater emotional fulfillment than an intellectually honest understanding of the universe I live in.

Teaching that to my sons and other students, is the best way I know to raise the profile of the atheist cause. Dawkin’s plea didn’t fall on deaf ears though, it did motivate me to want to write about being an atheist a bit more.

Poster Credit: Intergalactic Hussy

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