S03E16: The Excelsior Acquisition

Tonight Sheldon wants to ask Stan Lee how the Silver Surfer uses his silver surfboard to accomplish interstellar flight.  As well he should!   Nobody, not even Sheldon, knows how we are going to travel between stars.

The Silver Surfer accomplishes interstellar travel on his silver surfboard. How will we?

Proxima Centauri is our best bet.  It is the closest star to our home orbiting around our own star, Sol.   Proxima Centauri is  an unremarkable red dwarf star named appropriately from the Latin proxima, which is “next to”, as in “proximate”.  It is not so-named because it is close to us, but rather because it is close to the star Alpha Centauri, a star in the constellation Centauri.   Alpha Centauri is the third brightest star in the night sky, but mostly just because it is so close.  We may want try to visit someday.  After all we are neighbors and have yet to bring them so much as a fruit basket.

“Close” is a funny word to use on interstellar distances.   Proxima and Alpha Centauri are so far away it takes light 4.2 years to arrive.  Nothing we know of can allow us to travel faster than light, our ultimate speed limit.  Even the television transmissions of the pilot episode of Big Bang Theory, which have been traveling at the speed of light since late 2007, are only halfway to whoever might inhabit the rocks orbiting those stars.  Not even Hulu.com  in Alpha Centauri has TBBT available yet.  (Life near Alpha Centauri has that in commonwith Earth.)

Alpha Centauri, being so bright, has probably been known to the earliest hominids who bothered to look up.  But Proxima Centauri being so dim was only discovered using powerful telescopes in 1915.  We may not be done yet.  Even dimmer stars known as brown dwarfs may be traveling the galaxy even closer to us than Proxima Centauri.  These stars are so cool, you have to look for them in infrared light.   Finding such nearby stars is one of the key missions of the newly launched WISE satellite.   When I told one of the BBT writers/exec producers we may soon find closer stars than Proxima Centauri he said “The Federation may be closer than we think”.

Proxima Centauri (red star, center) is the closest known star to Earth at 4.2 light years distance. (If you enjoy astronomy pictures such as this one, I highly recommend visiting NASA's "Astronomy Picture of the Day")

Right now our plate is full just with interplanetary travel within our own solar system.  A trip taking astronauts to Mars, as recently imagined by NASA, even at its closest approach will take over half a year.  Proxima Centauri is 750,000 times farther Mars’s closest approach to Earth.  At the same speed, that would take over a quarter million years to get there.  We must invent something faster.

Suppose our human engineers develop a technology that allows us to travel 1% the speed of light on average to Proxima Centari.  The astronauts only need now to spend 400 years on the spacecraft.   (I’m ignoring the tiny  benefit due to time dilation slowing the astronaut’s lifespan as we discussed earlier for the story of Paolo and Vincenzo.) The astronauts won’t survive to get there, but if they keep having children their 16th generation could make it.  I don’t think the intermediate generations will be particularly happy with their forbears for condemning them to a lonely flight through interstellar space.  If one generation rebels, and refuses to procreate the mission will be a failure.   Even if that 16th generation arrived successfully, they would hardly be Earthlings.

I think we can prove that we humans will never attempt interstellar transit until we know how to travel at least 25% the speed of light.  (The mission to Mars discussed above is only 0.001% the speed of light.)   Suppose a mission really was undertaken to travel to Proxima Centauri with a fantastic new technology that would take us there at 1% the speed of light.  It will take 400 years.  Now suppose anytime in the next 200 years, a new technology is developed to increase that average speed to 2% per year.  Given the rate of technological progress that is not a bad bet.  So the spacecraft that launches later would beat the earlier craft.   So not until a technology reaches some reasonable fraction of the maximum speed limit, the speed of light, would anyone bother to take an early flight.   The speed would have to be as large as 25% the speed of light to nearly guarantee this would not be a problem.  At least then the same generation will arrive as left the Earth.  It may not ever be possible, but the argument shows it is unlikely any such mission would be mounted until that is possible.

These are the stars in your neighborhood. Each white ring is about 1.7 light-years appart.

(If some smarty-pants wants to suggest worm-holes or other space-bending technology, keep in mind that these ideas don’t even work on paper.)

This says nothing of the many other technological hurdles must be met.  Traveling even at 1% the speed of light, the spacecraft would suffer terrible damage from interstellar gas and dust.   The rate of cosmic rays, charged particles flying throughout interstellar space, would likely give fatal cancer to anyone who tried this mission and they would arrive long dead.

So it pays to go back and understand what is special about the Silver Surfer’s surfboard that allows interstellar transport.  Often science fiction writers will come up with an idea before engineers and scientists.   Perhaps with the Silver Surfer there is an idea we’ve missed.  A good place to start with any such questions is James Kakalios’s terrific book “The Physics of Superheroes“.  Yet no explanation of Silver Surfer can be found — maybe it is just because Silver Surfer started out as a super-villain, not super-hero.  Fortunately someone actually asked the Silver Surfer’s creator, Jack Kirby, why he uses a surfboard.  To which he explains:

“Because I’m tired of drawing spaceships.”  -Jack Kirby

Excelsior!

David