Wednesday, January 22, 2014

The Case for the Wow! Signal

I recommend Robert Gray's book The Elusive Wow! if you want detailed background on the Wow! event of August 15th 1977. The book also describes the author's efforts to replicate the signal. To date, no one has reported a reliable second detection of the Wow! Signal, although efforts to find it have not been persistent.

The Wow! Signal was a single 72 second event detected by the Big Ear radio telescope operated by Ohio State University, which was sweeping past the constellation Sagittarius at the time. This telescope was designed to conduct a survey of the radio sky, not to study individual sources in detail. The survey was successful and a number of new radio sources were discovered. After that, some of the science team thought that a SETI search would be a good use of the telescope.

I think the case against the Wow! Signal as an ET beacon is well known.

We are all well aware of the fallacy of the argument from ignorance. Just because the Wow! Signal has not been proven to be from a known source doesn't mean it's from ET. It's possible that the Wow! Signal was some sort of strange problem with the Big Ear's receiver that only occurred once, or that it was an extraordinarily elaborate and strenuous hoax. For these reasons, you would need to see independent confirmation, and we haven't; Robert Gray's single-handed and largely self-funded efforts to do so have been far from comprehensive.

Since the Wow! Signal was discovered after the fact, when Jerry Ehman went through a stack of printouts, it was too late to get another radio telescope to break off what it was doing, swing over and confirm the signal.  The signal was never confirmed, and no similar signal has been found in that region of space.

The are multiple reasons we think that the Wow! Signal may have been an ET beacon.

Tuesday, December 31, 2013

Where I am on the Drake Equation at the end of 2013

I'm sure you are all familiar with the Drake Equation. It's straightforward: SETI scientist Frank Drake devised it as a way to estimate the number of alien civilizations in our galaxy that we might be able to detect. It's only intended to be a rough guide, and has survived the last 50 odd years because it serves as a good way to divvy up the questions we will need to resolve to answer the bigger question, "Are we alone"?

There are many fine explanations of the terms of the Drake Equation easily available to you, so I won't repeat them. Here are few:

This is how the equation is usually written:

N = R* • fp • ne • fl • fi • fc • L

As we move from left to right across the equation, the terms become less and less well known and harder to estimate, even when we know more. The only thing we're sure of with some of the terms is that none of them are zero, since we are here.

In the last few years, there has been progress. We have gone from knowing just the first term with any kind of accuracy ( a factor of 2 or so), to having solid estimates of the first three terms, and we can now begin to conceive of a research program that would give us an estimate of the fourth term.

Remember, we are only interested in rough numbers here: we just want to know, is N a lot or a little?

So, for 2013, I think we are here:


When is absence of evidence = evidence of absence?

You often hear the old mantra "absence of evidence is not evidence of absence," but I think that this is an oversimplification. The truth is, sometimes it is, and sometimes it isn't. It depends on the experiment, and also how well you understand the implication of the results.

There are times when you can make an excellent case that something is absent because there is no evidence of it. If you are is small, well-lit room, you probably don't need to look under many things to convince any reasonable person that there is no tiger there. In general, you need two things:
  1. You need a solid argument for what sort of evidence you would expect if what you are looking for is there, and how that would be different from the null hypothesis (not there). 
  2. A set of data that tends to falsify the hypothesis, thus advancing the null hypothesis.
We're not talking about "proof" here. I would just as soon we not talk about proof much at all, unless the topic is logic or mathematics. Rather, it raising or lowering the odds of the null hypothesis, i.e. that the claim in question is not true.

Tuesday, October 22, 2013

Friday, July 26, 2013

Why Search?

In an earlier post, I argued that the current SETI program is not a silly waste of time if we want to search for ET and answer the question of whether we are alone, and I stand by that.  At the time I wrote that post, I didn't think that anyone would be interested in the why question. Of course we want to search, the only question is how, isn't it?  Maybe not for everyone.

All you have to do is to look at people like Frank Drake, Jill Tarter and Seth Shostak, who have
SETI Pioneer Frank Drake
devoted most of the careers to this topic, and you will realize that is is emotionally involving at a personal level, and not just "scientifically interesting".  It isn't purely a matter of scientific curiosity, and certainly not of ambitious scientific careering. 

Well, of course, the small number of people who study a topic are interested in it, and probably find it fascinating in some way.  What about everyone else?

So here is a question to ask yourself: if it was announced tomorrow that science knew for certain that there was another intelligent civilization in this galaxy, what would change for you?  Most adults are highly accomplished at keeping their own little worlds unperturbed.  Would the announcement of a distant ET civilization affect any major decisions you might make about your own life - your job, relationships, where you live, how many children you have, or any religious beliefs you might have?  Probably not you, but the younger generation, yes, because adolescents have left behind the comforts of childhood, and have yet to build their little worlds.  They don't mind being perturbed, and will often volunteer do some perturbing.  With announcement that we know about ET, their worlds just got much, much bigger.

Now it's not just Earthlings alone in the vast, cold universe anymore.  There are the others, possibly many others.  The universe no longer belongs solely to the astronomers, but is now alive, and belongs to everyone.