Dark energy: No, seriously, what the heck is it?

The fun thing about the Nobel Prize in Physics is watching pundits try to explain to the public the research that won. It doesn't always go well. Physics is not, shall we say, the public's best subject. (And I include myself in that "public".) Beyond that, words that describe legitimate concepts in physics have taken on new, more fantastical meanings in science fiction, which only serves to confuse people further.

That's why I like this video produced by KQED Science. It features Lawrence Berkeley Lab astrophysicist Saul Perlmutter, one of the winners of this year's Nobel Prize in Physics, and does a nice job of explaining what "dark energy" really is, why work with dark energy is worthy of a Nobel, and what Perlmutter and his colleagues have contributed to the expansion of human knowledge.

Video Link


  1. “what Perlmutter and his colleagues have contributed to the *expansion* of human knowledge…”

    Either a deliberate pun or an unconscious association… :)

      1. Hi — I love Boing Boing, and the work you are doing to explain science.  One correction — Saul’s work is on dark energy, not dark matter.  Dark energy was named as a parallel to dark matter — just to say that we don’t know what it is.  But it is somewhat unfortunate because the two are almost certainly unrelated.  I used to be in Saul’s group, and this is the subject of my research.  Here is a review paper I wrote on the subject (mainly for scientists): https://sites.google.com/site/dahowell/ncomms1344.pdf
        I’d be happy to write something explaining it for the public for Boing Boing — explaining science for the public is one of my other jobs.

  2. Does anyone else feel like Dark Matter and Dark Energy are cultural constructs meant to preserve old conceptions of physics that no longer fit with new data? 

    To quote from the above linked Dark Energy FAQ:
    “There seemed to be evidence that the age of the universe was younger than the age of its oldest stars. There wasn’t as much total matter as theorists predicted. And there was less structure on large scales than people expected. The discovery of dark energy solved all of these problems at once” Except of course no one knows what it is…. Or am I way off base here?

    1. Peter,
      I totally get the sense of what you are saying, and some scientists do feel that way.  But let’s take Dark Matter.  There are three ways of explaining it — (1) we are missing matter that we already know about, (2) there is a new kind of matter that we never knew about before, or (3) our conception of gravity is wrong.  Really (1) is the most conservative hypothesis, and preserves old notions, but there is very strong evidence that the Dark Matter is a new kind of particle that does not behave like the other stuff we know about (baryons).  People are working on modified gravity ideas, but nobody has anything compelling that explains the data.  So actually Dark Matter is new physics — new particles — it isn’t just a patch-up job at all.  

      Same thing with Dark Energy, only it is possibly more of a revolution.  That paragraph is a bit misleading.  The evidence for Dark Energy is very clear — we can map out how the universe has been expanding, and it is clearly accelerating.  It takes energy to do this, we just don’t know what the energy is.  This did happen to solve other problems, but it seems clear now that those other problems were caused by holding on too dearly to our preconceptions of how the universe ought to work and refusing to confront what the data was telling us.

      Think of it from another perspective — our monkey brains evolved to do a very specific things.  There is no reason they would have evolved to detect Dark Energy or Dark Matter, as they can only be seen on vast scales.  Science is full of stuff like this, from quarks to neutrinos.  There is overwhelming evidence they are there but the very narrow detectors we evolved can’t see them.  We have to build those using our brains.

  3. Great little video. I note that his only vague suggestion of an explanation for dark energy involves interaction with other dimensions. As a non-physicist, it strikes me that all the big unanswered questions seem to lead people in that direction. Why do some particles seem to rapidly blink in and out of existence? What the hell explains entanglement? And isn’t it true that String Theory involves 10+ dimensions? 

    My only humble suggestion is to look to cuttlefish for some of the answers. They’re colour-blind, but can mimic any colour perfectly – so I think they know something about light that we don’t, and if you think about it, they do look like something straight out of another dimension, a rather Lovecraftian one at that.

    1. Dark Energy is also a Morris dance team in the Palo Alto area.

      HR, classic string theory used 10 dimensions, but the membrane-theory folks say that in their cosmology, the number of dimensions goes up to eleven.  If you ask them why they couldn’t just use larger dimensions instead of small twisty ones and get by with 10 of them, they just look at you funny and insist that theirs goes to 11.

      Maggie, thanks for an interesting interview!

  4. They did not win the Nobel Price for their “work with Dark Energy” or proving that there is something like that. They got it for the experiment and showing that the universe is expanding faster than we thought and speeding up constantly.

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