That’s the question posed in the movie Talladega Nights: The Ballad of Ricky Bobby. Ricky Bobby wants to go fast and thinks that driving NASCAR fits the bill. Now that is a comedy for the general public, and to the general public, NASCAR is fast. For scientists, and science fiction fans, however, that’s a ridiculous position.
So, what is fast, then? And how fast can we go?
Well, let’s start with cars.
NASCAR racers average under 200 mph on the fastest tracks. World record cars—more rockets with wheels than cars—top out at over 700 mph, nearly the speed of sound. (That’s cool, but Buckaroo Banzai was able to drive his test car through a mountain.)
Aircraft, of course, can go much faster than that. Several times the speed of sound, in fact. For instance, the SR-71 Blackbird, which I first learned about reading X-Men, can fly at nearly 2200 mph. That’s St. Louis to Cincinnati in 8 minutes. Now that’s pretty fast.
But not fast enough to get you off the surface of the earth. For that, you need escape velocity and that’s some 11 miles per second.
Now, when talking about spacecraft speeds, or the speeds of planets or stars moving in their gravitational dance, kilometers per second are the units of choice. The Earth moves at 30 kilometers per second around the Sun. The Sun moves at just over 220 kilometers per second around the Milky Way. The Milky Way is falling through space at some 1000 kilometers per second relative to the microwave background radiation.
But, still, this is not really all that fast.
Jets from quasars, cosmic rays, neutrinos spewed forth from supernovas…ok, now we’re moving fast. 300,000 kilometers per second fast. Lightspeed. The ultimate speed limit.
Over a century ago, Einstein tried to imagine what it would be like to travel at the speed of light, and basically what he determined was that it would be pretty damn weird. The energy to accelerate to lightspeed approaches infinity, or you can look at it as your mass going to infinity. (I’m heavy enough, so I’ll choose the former perspective.) Time stretches out to infinity, too, which is a handy feature of relativistic travel. Back to this in a moment.
Our fastest spacecraft to date, Voyager 1, now pushing into interstellar space, is only moving away at about 17 kilometers per second, and it used a bunch of gravitational tricks to help get it going that fast.
Now, in principle, it’s possible to imagine traveling at close to lightspeed, but there are many practical problems. At lightspeed, specks of gravel hit like mountains, so those must be cleared out of the way one way or another. Rockets of various forms seem to fall short, requiring ratios of fuel-to-payload too outrageous to actually work. Spacecraft that don’t carry their own fuel work better: solar sails, laser or particle beam propulsion, or variations of ramjets that scoop up interstellar hydrogen as fuel on the fly. The energy and engineering both are daunting, but it may be possible, although unlikely given current understanding.
But when you talk about technology beyond the above imaginings…now that’s truly entering the realm of science fiction. Maybe dark matter particles, much more plentiful than hydrogen gas, could be made to serve as fuel. Maybe zero point (aka vacuum) energy can be exploited. Who knows? Breakthroughs are always possible.
In science fiction, of course, there are many ways to go faster than light. There’s the hyperspace of Star Wars, the warp speed of Star Trek, the space folding of Dune. And that’s just for starters. Faster than light travel is probably the most often used fantasy element in science fiction, and many of the consequences of this fantasy are not held to realistic treatments.
While it may cause a lot of science fiction fans to grumble when you say it, in the face of science today, lightspeed is a hard limit…maybe there are ways to cheat on Professor Einstein’s test, but not even Captain Kirk could do it with today’s understanding (short of reprogramming the entire universe, of course, and he would try).
This reality leaves many fans and visionaries depressed and in denial. It makes the universe look too big, they say, and our solar system the only pond we humans will ever get to swim in.
Except…there is another way of looking at the situation. With enough energy, enough speed, there is no practical speed limit in principle for the traveler.
The time dilation effects of relativity mean that time passes twice more slowly at 87% lightspeed, seven times more slowly at 99% lightspeed, a hundred times more slowly at 99.995% lightspeed, and infinitely slowly as lightspeed itself is approached infinitely closely. And a person moving at lightspeed, perhaps transformed into photons by an unknown technology, could travel everywhere in no time.
Now that would be fast.
NASA may be or may not be the future of manned spaceflight, but they’re one of the main players today and may be tomorrow, too. So, can you imagine it? An overlap of fans of car racing and science fiction, sitting down together to cheer on NASACAR? Astronauts racing to the stars? Eventually approaching lightspeed itself? Who knows what the future holds?
So, is there anyone out there who wants to go fast?
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You forgot (or did not know about) the instant transport method described in Orson Scott-Card’s Ender saga (can’t remember which of the volumes right now, 5th, maybe).
Since this is my first reply, i wish you all a long and prosperous LightSpeed!
Cheers,
John
Mike, your mentioning of NASCAR brings to mind a collaborative novel I wrote back in in the 80s called “Roger Zelazny’s Alien Speedway: Clypsis.” Guess who the collaborator was. (Actually Roger wrote the background, and I wrote the novel.) The setting was a solar system, Clypsis, dedicated to the racing of faster-than-light spaceships–in a great, looping FTL tube that circled the star. The hero was a kid who wanted to race faster-than-light ships so bad he could taste it. Eventually, of course, he got to. There was a little bit of me in that kid.
Jeff, that sounds like a perfect fit here!
I like Hawking’s take on it
http://dsc.discovery.com/videos/stephen-hawkings-universe-our-interstellar-future.html
And I also wish Lightspeed all success!
Makes me wonder if it will ever be possible to go lightspeed without actually BEING light. When you accelerate to the point of lightspeed, do you simply become photonic light? Do you join the cosmic consciousness that Deepak Chopra speaks about, that non-local consciousness that is the root and source of all physical matter in the universe? In other words, will “simply” going the speed of light bring you into the Great Soul at the heart of material reality, forcing you to abandon your physical being in exchange for the boundless creative consciousness that is the Heart of Creation? Is that boundless force, which scientists would call the Unified Field, is it made of light? Or something even beyond light? Is is possible, in some distant future, to travel at the speed of light without being “devoured” or “absorbed” into the Unified Field that comprises all of celestial reality? And if not, is there any way to return from such an absorption? How could a human mind survive? Would this be the same thing as dying?
Is this, in fact, exactly what DOES happens when humans die? Do our souls/spirits/consciousness (our “inner light”) get re-absorbed into the source of all celestial being–the Unified Field/Cosmic Consciousness?
Would traveling at the speed of light equal annihilation? Or cosmic rebirth? Or something else entirely?
I think we’d better stick to wormholes and space-folding and hyperspace….
Cheers,
John
I believe that Einstein’s math doesn’t allow for travel at the speed of light, the equations fall apart, result in infinity or division by zero or something. But if one were to somehow consciously reach infinitesimally close to the speed of light, they would see the universe expand into flat space, trillions of trillions of years pass in a flash. Only the traveler stops aging, not the static universe.
Re: At lightspeed, specks of gravel hit like mountains,
Thanks for writing about that. I rarely hear folks mention hitting tiny objects when discussing light speed and how to get around it. Becoming light is a good solution. Hopefully rematerializing correctly.
I’ve had relativistic starships in my novels and worried about this a lot. In the first one I had high-powered lasers vaporizing everything the the ship’s path, ionizing it, too, so that it could then be moved safely around the ship with magnetic fields.
There’s probably not a lot of junk in deep space. Not until we get out there and smash things up.
That’s a good idea. Magnetic fields. I use plasma fields in mine for possible gamma ray strikes for slower moving space vehicles. I haven’t written rel.starships yet. It’s too hard. I’ll get your first book at some point. I’m reading Spider Star now but I’m only on page 40 so far and haven’t gotten to the starship parts yet. Fast is cool!
As a minor correction: you only need to be travelling 11km/s to leave the earth’s gravitational field if you expect to do it by going down a big ramp on your bike and then launching yourself straight up a ramp. I.e. you need 11km/s all at the beginning, so that by the time you slow down to a stop, you’re now infinitely far away from the earth. (And, likely crashed into something else, if your bike has no other means of propulsion.) If you want to, you can get all the way to outer space without ever topping 25mph. It would take a while, but it would work just fine. What we actually do is somewhere in between. According to NASA, at the 2 minute mark of a space shuttle launch (just before the the solid rocket boosters separate) the shuttles speed is more than 4,828 km/hr, which is well short of the 11km/s “escape velocity”. But at that point, the shuttle is also 45km above the surface of the earth already.
As an aside (as if my whole comment here weren’t already) I believe the 11km/s escape velocity is the simple calculation of the initial velocity required to escape the earth’s gravitational field, and does not factor in air resistance, which would be pretty significant at those speeds.
I was just using the simple escape velocity, so yes, Clark, you are correct. Nice attention to the detailed physics! The 11 km/s is the speed you’d have to shoot a cannonball (in the absence of air resistance, yes!), for it to leave the Earth.
As you point out, it is possible to reach space going more slowly. A space elevator or a “stairway to Heaven” or some other thing like that will let you do it. Energy costs will be similar, but the speed is not technically necessary.
It’s fun to get into the details of this stuff!
Loved the reference to NASCAR. My son used to talk about how fast a Ferrari accelerates or a Shelby Mustang. My rejoinder was always to strap-on an F-14 and try a catapult launch. As to super-light speed, well that is something all space junkies dream about. How we figure it out will depend on how soon we are able to explore the universe. Before Einstein there was Newton, but Sir Isaac could never see the universe the way Einstein was able to. Sometime in the future we will be able to see the universe in an unexpected manner which will lead to new ways of thinking and new ways and means of transportation. I just hope that I am around at that paradigm shifting moment and realize it. Here’s to that time when moving through space-time becomes real.
About that whole “tiny objects hitting at the speed of light” thing…isn’t that why most sci-fi starships have “shields”? (i.e. force fields that surround the ship to protect it from miniscule space-matter punching a hole in the hull) Everybody thinks about the “shields” as protection during space battles, but that’s obviously got to be a secondary function (and they never last very long under laser-fire anyway, do they?).
Shields up!
I read an article on the realism of warp drives and the way it was written it was fairly convincing that by warping the field around the ship at close to or ftl, can’t recall which, the ship was inside a time space bubble that protected it from pieces of matter.
I’m going to play it safe and assume Einstein was right and FTL is not possible. I’m also going to assume we won’t invent any superscience means of travel any time soon. But with technology we could put together within the next 25 years, what is the fastest we could send a robot probe to Alpha Centauri?
Say there was a trillion dollar X-Prize for such a trip, could our robot reach Alpha Centauri in 100 years, 1,000 years, 10,000 years? What’s the best interstellar hot rod we could build now?
If we’re willing to go nuclear, it’s on the order of thousands of years, if I remember my Project Daedalus correctly. Bomb after bomb after bomb will get us to a small fraction of lightspeed. I hope we’ll do it.
I remembered wrong. On a couple of counts. Have to do your research for science and hard science fiction, every time.
Daedalus is based on nuclear fusion, technology still quite beyond us.
Project Orion, however, based on using nuclear bombs to accelerate a ship to several percent of light speed, could be developed within decades and reach Alpha Centauri in under a hundred years. If people decide it’s cool to blow up nuclear bombs in space…and after the stink over launching a little plutonium for the Saturn Cassini mission, I doubt it. And then there’s the danger of releasing Zod and the other phantom zone criminals…