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Our future, our universe, and other weighty topics


Thursday, February 11, 2016

Scientists Have Detected Gravitational Waves (Yawn) : Why It May Mean Little

It was announced today that scientists have detected gravitational waves, something they have never previously observed. The gravitational waves were detected from the extremely rare event of the merger of two black holes. The detection was made by the very expensive LIGO project. Although some scientists are speaking as if this is some epic breakthrough, it may have relatively little meaning in the grand scheme of things. Buried within the long triumphant announcement in the Washington Post is this statement: “There is no obvious, immediate consequence of this experiment.”


One reason why the detection of gravitational waves may mean relatively little is that apparently no door has been opened to a new cost-effective method of astronomy. Let's look at the facts about how much was put into LIGO and what the output has been so far. More than 600 million dollars has been invested into LIGO, which required a huge architectural infrastructure. After years of effort, the project has produced a single detection of gravitational waves, from a very rare event involving the merger of two black holes. Does this offer some hope of some great new method of cost-effective astronomy? Quite the opposite. A project in which you spend 600 million dollars for a single observation is millions of times less cost effective than alternatives. I can spend $1000 on a Celestron telescope, and use it to make thousands of observations, for a cost of less than one dollar per observation.

Has the detection of gravitational waves changed our understanding of the universe? No, because the existence of gravitational waves was already predicted by Einstein's general theory of relativity, which almost everyone already believed in. Has the detection of gravitational waves been a case of giving some needed support to a tottering theory that people were starting to question? No, there was already tons of evidence in favor of the theory of general relativity. A new observational confirmation for the theory of general relativity is kind of like giving another billion dollars to Bill Gates.

The interesting questions in physics and cosmology are questions like these:

Why did the universe suddenly begin billions of years ago in the Big Bang?
Why are the fundamental constants of the universe so exquisitely fine-tuned?
Are there any reasons for believing in a universe beyond our own?
Are there any reasons for believing in parallel universes?
Why does light sometimes act like a particle and sometimes like a wave, depending on how we observe it?
What is this strange thing called quantum entanglement, and does it point to a far greater amount of connectivity in the universe than we previously imagined?
Does quantum mechanics imply a new outlook on consciousness, in which the observer is king?
Why is the universe so astonishingly ordered on a large scale?
Why is the vacuum of space relatively empty, when quantum mechanics predicts it should be something totally different, teeming with something like “zero-point” energy?
Why does the universe have its particular set of laws that favor the existence of living things?

As far as I can see, the detection of gravitational waves casts no new light on these questions.

Is there any chance that we might be able to do observations like that of LIGO many times more cost-effectively? Not really. LIGO used a pair of observatories that each used “ultra high vacuum systems” with an L-shape measuring 4 kilometers (2.5 miles) on each side. There is little prospect of being able to shrink something like that to something that your local college can use.

The press stories are comparing the LIGO project to a moonshot. It's nice that this particular moonshot has succeeded, and I congratulate the scientists who achieved this very expensive triumph. But it must be remembered that from a “science payoff” perspective the moon landing program was something of a dead-end boondoggle. After paying a king's ransom for moon rocks, we didn't learn much of anything new. A similar situation may exist in regard to observing gravitational waves. Just as going to the moon to pick up rocks is the opposite of a cost-effective method for geological observations, projects such as LIGO may be the opposite of a cost-effective method for astronomical observations.

Postscript: I may note that gravitational waves have no practical use.  It's a trillion times easier to use electromagnetic waves for communication, and electromagnetic waves are just as fast; so it's hard to imagine that anyone will ever be using gravitational waves for communication. 

Of course, a science mission with no practical benefits may be justifiable if it yields lots of nice visuals, lots of eye candy for the public to enjoy. The mission to Pluto had no practical benefit, but produced some nice visuals. But we have got not a single decent visual from the LIGO project. We could have got better visuals with a $1000 Celestron telescope.  

Post-postscript: It turns out the total LIGO cost was more than a billion dollars. John Horgan asks in Scientfic American whether it was worth the money, and quotes a historian of technology who seems to think the funds would have been better spent in other ways.