Thursday, February 04, 2010

Where Are They?

[M31, Andromeda Galaxy, is the Milky Way's near-twin and binary partner, that is, they are in orbit around each other. It is the nearest large galaxy to ours. It is 2.5 million light-years away so the picture is of how it looked 2.5 million years ago. The light from the far side is 100,000 years older than the light from the near side.]
I have never understood Enrico Fermi's question about extraterrestrials, "Why aren't they here?"

It is the same question as "Why haven't we ourselves sent starships all over the galaxy?" The answer is special relativity - it would require an immense and immensely powerful ship to accelerate to near-light speed and then to decelerate down from it at its destination. And seen from earth it would take thousands of years for such a ship to reach even the nearest star, 4 light-years away.

If the first people ever to live in a city, in addition to building the walls of Jericho 9,000 years ago, had built and sent out a starship to the nearest star at near light speed, it would still be en route today. Our galaxy is some 100,000 light years across. It is pretty damned obvious why extraterrestrials have not visited us. Even if it were physically feasible for them to do it, no small supposition, since the beginning of our civilization there has not been time enough for them to get here.

Yet Fermi was no fool. One of the leading scientists of the Twentieth Century (and, interestingly, an Italian Jew), he won the Nobel Prize for Physics in 1938. He has a subatomic particle, the fermion, an element, fermium, a research laboratory, the Fermi Accelerator National Lab, and a space telescope, the Fermi Gamma-ray Space Telescope, named after him. I on the other hand have a blog and a lot of opinions. Even so I am willing to bet that I am right and he is wrong. Unless there were money involved, of course. Then I too would bet on Fermi. So what am I missing?

My guess is that Fermi was not as impressed as I am with special relativity. He knew Einstein personally and perhaps understood him and his physics to be as fallible as anyone else's. My guess is that Fermi saw 20th Century physics as just that - a science that would be superseded in the centuries to come, just as 18th and 19th century science had been in his time. Otherwise his remark makes no sense.

We already have intimations of that in the study of quantum entanglement, effects that operate instantly over unlimited distances. Though these are wispy subatomic things, subtle quantum effects, they nevertheless reflect something about reality that doesn't give a damn about special relativity. So maybe during the coming century or the one after it, special relativity itself will be shown to be a special case of something larger, just as it did for classical Newtonian mechanics. If that should turn out to be true, where the hell are they?


  1. Christy12:44 PM

    Pfft. We all know that you have to break the warp speed barrier before first contact with extra-terrestrial life can be initiated.

  2. Anonymous1:58 PM

    They are among us...Victoria Beckham looks like she may be an alien. And I heard that Jack employs aliens to work on his house.

  3. An ET-10:23 PM

    Your assessment of Fermi's remark is interesting, but some of your facts miss the mark. First, you're right about the reason we on Earth have not sent ships "all over the galaxy", but what about "locally", like out to a few dozen light years? The problem here is finding an economically feasible propulsion system to travel at about 60% of light-speed, where relativistic effects on mass and energy, though noticeable, would not be large enough to overcome. Although this technology hasn't arrived yet, who is to say what progress could be made in the next 150 years? In theory, at least, ion propulsion systems could get a ship up to those speeds, and back down.

    An example -- Sirius, the second-closest star, is 8 light-years distant. If a ship could reach 80 % light-speed, it would only take 10 years Earth time each way, or 20 years R/T. For those on the ship it would take only 6 years each way, or 12 years R/T, due to time dilation. Of course the practical limit to this technology would be to stars only out to maybe 50 light-years, unless speeds of up to 90% of light-speed could be obtained. We haven't discovered any earth-like planets yet, but if they're out there within those distances it is not inconceivable that an advanced civilization could get here.

    And here's something interesting -- The Dogon Tribe in Africa claim they are descended from "Star People" who came from Sirius-B, a dim star orbiting Sirius which can't be seen without a telescope and which was unknown at the time their tradition began. True or not, this scenario is quite possible if the "Star People" had even 50% light-speed technology. Of course, if it is true, then we have to re-think all of human history.

    I'm betting on Fermi, but maybe he didn't look hard enough.