Tuesday, January 25, 2011
By Doug Watts
with apologies to Dr. Phil Plait,
the original Bad Astronomer.
If the Earth was a foot from the Sun the next nearest stars would be 50 miles away.
Space is aptly named.
Watching old Star Trek re-runs my wife reminds me that in the later versions of the series the producers tried to keep the scripts somewhat close to science.
But if this were truly true, you really couldn't have a show. You'd mostly have this:
This is not to knock Star Trek, which has always been one of my favorite TV shows, but is more about having some fun with science.
Star Trek requires that in 200-400 years people in space ships can travel megazillions of times faster than the speed of light. This is illustrated by stars zipping past the ship's view screen as if they were farm houses zipping past as you drive down a highway. This is done, of course, to show us viewers that the ship is moving really fast.
Except in the dense center of our galaxy, the average distance between stars in the Milky Way is around five light years: 30 trillion miles. So we can estimate the average travelling speed of a ship in a typical Star Trek set-up shot as about 5 light years per second, or 30 trillion miles per second. In contrast, light pokes along at a measly 186,000 miles per second.
5 light years per second is 300 light years per minute; 18,000 light years per hour and 432,000 light years per day. This is problematic for a 'sciencey' show set in the Milky Way Galaxy.
The Milky Way is a barred spiral galaxy about 80-100,000 light years in diameter. Its width (from top to bottom) is about 16,000 light years at the central bulge and gets much thinner as you move out from the center bulge.
This means that at the ship speed shown in a typical Star Trek episode, the Enterprise would travel all the way through the Milky Way in about six hours. If the ship was aimed in any direction except parallel to the disk of the galaxy, the ship would be completely out of the Milky Way Galaxy and into the emptiness of intergalactic space in just a couple of hours. The ship would arrive at the Large Magellanic Cloud, our nearest galactic neighbor (160,000 ly), between breakfast and supper and would reach the Andromeda Galaxy (2.5 million ly), our nearest large galactic neighbor, in a week.
Andromeda on 5 Quatloos A Day
In a favorite early episode of mine, the USS Enterprise is hijacked by the deliciously suave and evil Rojan (Warren Stevens) and his friends from the planet Kelvan in the Andromeda Galaxy so they can use the Enterprise to get back home. Because the journey to Andromeda will be so long, they turn the whole Enterprise crew into little styrofoam icosahedrons and soup up the Enterprise so it can go a zillion times faster than normal, which is already a megazillion times faster than the speed of light.
However, even at normal Enterprise speed, Rojan and the Kelvans could get home to the Andromeda Galaxy in a bit more time than it took for Kirk to beat up Rojan and make out with his hot wife Kelinda (Barbara Bouchet), who like, all Kelvans, is actually a 100 tentacled creature.
The Great Energy Barrier at the Edge of the Milky Way
A Star Trek staple is that a giant 'negative' energy barrier surrounds the Milky Way Galaxy that no normal matter, like a space ship, can pass through. This is a critical plot point in the episode with Rojan, Kelinda, Tomar, Hanar and Drea of the Kelvans, since Kirk has the chance to flood the engines of the Enterprise with this negative energy and blow up the ship as they pass through the Great Energy Barrier. But instead, Kirk decides the best way to save the Enterprise is for Scotty and Tomar to get totally shitfaced:
For Spock to whip Rojan's ass at three dimensional chess and for Kirk to get all Barry White with Kelinda and then beat the crap out of Rojan when he gets jealous.
The Great Energy Barrier? It doesn't exist. Even when Gene Roddenberry was first outlining the series, no scientist ever speculated such a Great Energy Barrier existed. He made it all up. But it's still kool.
Star Trek Voyager: Too Fast and Too Slow?
Star Trek: Voyager is a weird cross between Star Trek and Gilligan's Island and Lost in Space but is more ridiculous and contrived than all combined, if that is possible.
When Voyager begins, we are told the ship has been throttled by a weird alien dude into the "Delta Quadrant" of the Milky Way Galaxy, far from the "Alpha Quadrant" where Earth is located and all the other Star Treks are set. Then we are woefully told that even at 'maximum warp speed' it will take 70 years for Voyager to return home to the "Alpha Quadrant."
A quadrant is one fourth of the galaxy, so this means there is a maximum of about 50,000 light years between the outermost edge of the "Delta Quadrant" to the center of the Milky Way Galaxy and into the inner part of the "Alpha Quadrant." This equates to travelling 50,000 light years during 70 years; or a speed of a bit less than 1,000 light years per year of travel which equates to 1,000 times the speed of light.
But even at 'moderate warp speed,' Voyager is shown in typical 'Star Trek' mode whizzing by stars at the rate of a half dozen stars per second. This speed equates to 432,000 light years per day. At this speed, Voyager would get back to the Alpha Quadrant of the Milky Way not in 70 years, not in 7 years, not in 7 months, not in 7 weeks, not in 7 days, but in about 7 hours.
This ship speed, which is zillions of times faster than the speed of light, raises some troubling functional issues. How do you steer that fast? How do you stop? How do you swerve around all those stars? How do you even see the stars?
Deep Space Nine and the Worm Hole
Aside from that it might be the best series of the series, Star Trek: Deep Space Nine, uses the premise that a 'worm hole' exists in the 'Alpha Quadrant' that leads directly to the distant 'Gamma Quadrant' of the Milky Way. All types of fun and death then ensues. The problem, again, is that at the speed the Star Trek ships are shown routinely travelling, they could reach the 'Gamma Quadrant' in a few hours without even using the 'worm hole.' Oh well.
Captain, we've a wee bit of a problem.
In 'Star Trek' terms, the speed of light is really slow, like riding a bike with square tires up a steep hill.
Real science is way weirder than even the weirdest science fiction. And it's also real! One of the weirdest parts of science is Special Relativity, which deals when stuff, like us, goes almost as fast as the speed of light.
Swiss Patent Clerk Albert Einstein published his scientific paper on Special Relativity in 1905. The most important 'take home' message of his paper is that nothing can go faster than the speed of light. The only thing that can go as fast as light is light.
Special Relativity is Actually Pretty Simple
Special Relativity does two things to stuff like you and I if we are moving very close to light speed.
1. It makes us more massive.
2. It makes time slow down.
It does other stuff too, like make us shorter in the direction of motion, but we need not deal with that now. These two are plenty weird enough, and have actually been proven in experiments with little tiny itty bitty things like protons and muons, which are the only things we've ever been able to speed up to something approaching the speed of light.
A lot of Special Relativity deals with the weird things that happen to matter as it gets close to the speed of light. And since SR is a set of mathematical equations, we can look at what would happen if a piece of matter actually reached the speed of light.
Well first, it would become infinitely massive, as in it would weigh more than the entire Universe put together. There goes the diet plan !!! 
Also, time would stand still, so starting that diet could always wait until tomorrow, since it would never come.
It's a procrastinator's dream come true. With infinite food !
The SR equations dictate that a piece of matter would become infinitely massive if it could reach light speed, and as such, it would take an infinite amount of energy to make it actually reach light speed, so the whole Enterprise would kind of grind to a speedy halt.
But on Star Trek, the entire ship travels not just at the speed of light, but way way way faster than the speed of light. So this is a problem.
The Whole Time Stops Part
Assuming you could get a ship to go at light speed, time would stop. Time wouldn't stop outside the ship, but it would stop inside. At light speed, you would be everywhere at once. You'd be where you were and where you are, all at the same time. Because time stops. The concept is so bizarre that Albert Einstein decided one afternoon that only light can do this or else we would all go insane. 
But there's an even bigger problem. To reach the speed of light you first have to reach almost the speed of light, like say .9999999999999 ... the speed of light. At this speed, time seems completely normal inside your ship. However, time everywhere else, including on Earth is moving 99.999999999 ... percent faster than your time. So within a few seconds of travel by your clock, not only is everyone you know on Earth long dead, but the Sun has died out and so have all of the stars you are trying to visit. Long before you get 'there' there is no longer any 'there' to get to.
And this is just at near light speed, never mind zillions of times faster than light speed, like the USS Enterprise.
If a ship could travel faster than light speed, time in your ship would have to move backwards as compared with the rest of the Universe. You would arrive at your destination billions of years before you had left. Captain Kirk would have to give the order to go to warp speed billions of yearsbefore he was born; and before life had evolved on Earth!
Slower is Faster and Faster is Slower ?
One of the weirdest parts of Special Relativity is that a space ship going very close to the speed of light, from Earth's perspective, takes longer to get to its destination than if it goes slower. Say what?
With your ship travelling at 99.999 the speed of light, your ship clock seems perfectly normal. However, based on clocks back on Earth, your clock is running 223 times slower than theirs. So in one year of space travel according to your clock, 223 years have gone by according to clocks on Earth. So by travelling at 99.999 percent of light speed, in one year by your clock you have travelled almost a light year. But according to the clocks on Earth it took you 223 years to go that far.
So while according to your instruments, your speed is almost about 6 trillion miles per year; according to Earth your speed is a measly .026 trillion miles per year. Why, because according to Earth's clocks, your year is 223 times longer than theirs.
Now, on the other hand, if you travelled at only one tenth of light speed, it would take 10 years to travel a light year by your clock. Because of the scaling in the SR equations, according to Earth's clocks, your year is only 1.005 times longer than theirs, which is not bad. So from Earth's perspective, who are waiting for your scientific observations, they will get your information a lot faster if you go a lot slower !!!
How is this so? Basically because nature so abhors massive things going close to the speed light that it penalizes you for doing so. This penalty comes in the form of forcing your friends clocks on Earth to go much faster than yours (or to put it another way, to make your clock go far slower than theirs). At 99.999 percent of light speed, 223 years will pass on Earth in one of your years. If you ever want to see your friends again, you'll need to slow way down.
Light Speed Ate My Homework !!!
Because time dilation increases asymptotically under SR, the penalty for extreme speed so extreme that it is completely destructive to information. Let's say you orbit the perimeter of the Milky Way at really close to light speed. As you look out your window you will see stars burning out every few seconds and within a few weeks or months watch the whole galaxy turn off. Sure, you can write The Definitive History of the Milky Way Galaxy, but who besides you will be around to read it?
You'll Smash Into Exploding Stars All the Time
Once you're going really really really close to light speed, your clock is moving tens of thousands or millions of times faster than the clocks on the stars you approach. At a certain point stars are going to be randomly exploding around you like popcorn. Even worse, nearly all stars have relative velocity: they are moving on their own trajectory and speed within the galaxy. But because your clock is so slow compared to theirs, all your star charts will become obsolete almost as soon as you make them. The stars will be buzzing around you like deer flies and exploding every few minutes or seconds. It'll be like trying to run between the rain drops in a downpour !!!
You'll Get Fried by Gamma Radiation !!!
Because light cannot travel faster than the speed of light, when you approach a luminous body (or it approaches you) the light appears blue shifted, ie. its frequency increases and hence, its energy. If your ship is travelling super close to light speed, the light from any approaching star would be so blue-shifted it would reach the frequency of gamma rays and totally fry you and your ship.
Be Your Own Black Hole !!!
Another problem is that once you accelerate your ship really, really, really close to light speed, the ship's mass becomes so large that your ship becomes a Black Hole. This raises another "time stops" issue since under General Relativity, time runs slower in strong gravitational fields, and goes really slow inside a Black Hole. And of this would happen before you reached light speed.
Captain, we just Phased Ourselves !!!
If your ship is travelling faster than light speed and you shoot a 'phaser' or 'photon torpedo' at something in front of the ship, you're going to hit yourself.
Why is the Enterprise Viewscreen Not Totally Black?
While the Enterprise might be travelling faster than light speed, the light from stars and ships up ahead of it is not. That light is still poking along like a lame donkey up a hill. Even under Star Trek Rules, the Enterprise would have to rely on paper charts to tell them where they are since any real-time information about where they really are cannot reach them until they've gone by it. Talk about an unfair drivers' test! This invokes the Sulu Paradox, ie. light speed is not additive to ship speed. At warp speed, you're flying blind.
Captain, the Sensor Readings Show Nothing.
Like the warp drive, sensors work perfectly except when you need them to work. Then they fall apart. The sensors give Spock something 'sciencey' to do while Kirk signs a space clipboard and checks out Yeoman Rand's gams. At 'warp speed' sensors could not work. This is why Spock always looks into the viewfinder and says, "Fascinating."
But Haven't Prominent Physicists like George Lucas Said Warp Drive is Possible?
Yes, but so are light sabers. The idea of real 'warp drive' uses the concept of 'dark energy,'theorized as being responsible for the continuing expansion of the Universe, ie. of spacetime itself. Dark energy apparently does exist; and as theorized dark energy does violate the speed of light, but only makes itself felt at scales of hundreds of millions and billions of light years. That last part is critical.
We know from examining the light from the most extremely distant galaxies that they and us are moving apart from each other faster than the speed of light. But while this 'dark energy' expansion of the entire Universe is dominant at scales of 5-10 billion light years or more, it is far weaker than other forces, like gravity, at interstellar scales. This is why 'dark energy' does not cause the Milky Way Galaxy to fly apart, for binary stars to fly apart , for the Earth to fly away from the Sun and the Moon to fly away from the Earth.
At planetary, interstellar, galactic and even intergalactic scales, gravity holds the upper hand, in the same sense that at very close distances, a couple of toy magnets on a toothpick can hover over one another and 'defy' gravity.
The idea behind a Star Trek-like warp drive is to create a bubble of "dark energy" directly behind your ship that would radically expand the size of space right behind you, and create a 'wave' in spacetime that you could ride like a surfer, or something, toward your destination.
This concept at least has the attraction of building from actual cosmological constructs. But its application raises more issues than it solves. As in all travel, you want to get from 'here' to 'there' as quickly as you can. Warp drive is sort of like thinking of the U.S. as a big flat carpet and pulling it into enough big wrinkles, or waves, so that Los Angeles is suddenly (and temporarily) just a few miles outside Boston. But what happens to Kansas? Doesn't it all get scrunched up? And what happens when you 'unwrinkle' it? Does everything jerk right back to where it was? Do any dishes get broken?
For example, if we want to wrinkle, fold and crinkle all of the space between us and our destination, say the center of the Milky Way Galaxy, there are millions of stars and planets in between. What happens to them? What happens to them during the scrunching and unscrunching process? What happens if somebody else is scrunching and unscrunching space at the same time we are? Whose scrunching takes precedent? Can you unscrunch somebody else's scrunch? Why aren't we observing all this scrunching going on right now; with stars zipping back and forth across the sky, scrunching and unscrunching everytime a ship goes into warp drive? What happens if you don't scrunch and unscrunch the Galaxy just right? What if Lt. Sulu screws up at the helm because he's checking out Lt. Uruhu's legs?
But what if what if?
Okay Mr. Pessimist McPessimisticky, people thought for millennia that the Sun went around the Earth. Perhaps in 400 years we might discover that our 'laws' of physics are just as wrong as the 'laws' that people believed in the Dark Ages. Fair enough.
The problem is that our contemporary laws of physics are scientifically verified; the 'ideas' of the Dark Ages were not. Our contemporary physics explains natural phenomena very well. To develop a totally new physics we're also going to need a new reality, which is tough.
We now have particle accelerators that can bring tiny bits of matter up to about 99.99999999 percent or so of light speed. In these experiments, the equations Special Relativity are quantitatively and qualitatively confirmed.
When protons are accelerated to very close to light speed, they become more massive, at exactly the amount predicted by the equations of Special Relativity. At near-light speed, highly unstable particles like muons live much longer before decaying, showing that at near light speed, time slows down, by the exact amount predicted by Special Relativity.
So to have Star Trek, we need to get rid around Special Relativity.
Lighten Up Yourself
Relativity could also be called "No Free Lunch" or "Something Has to Give." The phrase, "relativity" is wrong; the antonym "invariance" is what Einstein preferred, which is fancy for saying some things can't be changed. That something, is c, the speed of light in a vacuum. By establishing this as a postulate, Einstein had to rejigger a whole bunch of accepted physical laws. Then he challenged the World to prove him wrong, thereby creating the Internet.
What's cool about relativity ... err ... invariance is that time is the variable, which we always assumed was a constant. Light speed always stays the same so something must change. Time is what changes. This is the stuff you think about when you're bored at your job at the Swiss Patent office. Job boredom is good!
If somehow we could be turned into pure light, we could travel at the speed of light. We'd just have to get turned back into non-light. And since, at light speed, time stops, we can be where we were and where we are at exactly the same time. Kool! The problem is that time doesn't work like that for all the people (and stars) who are not going at light speed. So there's kind of a trade-off.
Remember that the real problem with accelerating a piece of stuff to light speed is (a) you can't and (b) getting from the next to last decimal to the last decimal will take a megazillion years. And you'll weigh more than the entire Universe.
Good News and Bad News
The Good News is that we have already reached the next nearest stars, and quite a few beyond that. The Bad News is that most of what has reached these stars from us is bad 1960s music and Threes Company episodes. Why? Because radio and teevee travel at the speed of light!
Right now, we are sending our crappy music to Sirius and they are hearing it. The problem is sending the musicians there so they can do a live gig.
The 'speed of light travel problem' is really about listening to Led Zeppelin on the radio from your planet orbiting around Sirius as opposed to having them come over to your house and playing "Achilles Last Stand" after supper. The more important problem is transporting relativistic amounts of Peruvian blow for 30 trillion miles and having some left for after the gig.
So the problem with interstellar space travel is that we desperately need to send Pat Boone to play live on Alpha Centauri rather than playing "In a Metal Mood" on the radio. Which, come to think of it, is a good way to encourage an interstellar invasion force from Alpha Centauri coming to kill us all off. But then we wouldn't get a Ricky Nelson song about getting dissed at a garden party 4 light years from Earth. So it's a trade-off.
Are we just being selfish? Are we like kids in the back seat screaming that if we don't go to McDonald's on Proxima Centauri we'll hold our breath until we turn into a blue giant? Is that what it will take to get a Star Trek future? Christ, we're already sending our crap there by radio. Do these innocent aliens really want -- or deserve -- the punishment of the real thing? We can't even get a concert on Earth that isn't lip-synched. Why should they get better? These are questions NASA needs to answer.
We Die Too Fast
The real problem with interstellar travel is that human lifespans are too short. If humans could be genetically engineered to be close to immortal, then long space journeys would not be a problem. Many Earth microbes are close to immortal in that they can go into virtual suspended animation and when living conditions are favorable, come back to active life. Unfortunately, it appears that a key to this ability is that these microbes have extremely simple physiologies. However, if the suspended animation skill of these microbes could be 'grafted' by genetic engineering into the various cell types of humans, it would perhaps be possible for a human to sent into space, turn off their cells and turn them on again in response to a specified environmental cue.
Perhaps the most promising path is quantum computing. If every single cell in your brain could be digitized into binary code and stored in a quantum computer, the computer itself could be put in a ship and sent off into space. This means you would be a computer and no longer a human, but if your 'consciousness' was somehow preserved it wouldn't be a bad trade-off if space travel is that important to you.
Note, however, that none of these ideas, even if they could ever be achieved, give you 'warp drive' or 'sub-space' communications or the other faster than speed of light staples that space fiction depends on. A message from "Star Base 12" located 10 light years away will still take 10 years to reach you. Accelerating a space ship to the speed of light, even a ship the size of a single proton, will still take more energy than exists in the entire Universe.
By Special Relativity, we know that light can travel at the speed of light because a photon of light has no mass. So if we could conjure up something that had a property called 'negative mass' then an object made of negative mass might be immune to the light barrier. But what exactly is 'negative mass'? Could the cosmological constant, inferred to be a 'negative energy' (or 'dark energy') that is causing the Universe to expand, have a complementary partner, 'negative matter,' just as energy has the complement of matter? (Note that 'negative matter' is totally different concept from anti-matter, which is bound by the same physical laws as matter).
Aside from the lack of any theoretical or observational evidence that 'negative matter' actually exists, there is the more practical matter of how we would interact with it. But assuming it does exist and we could interact with it and use it to convey meaningful information and this information could be conveyed without regard for the light barrier, there is still the time travel problem.
Remember that in Special Relativity, a photon has no sense of the passage of time. A photon that takes one billion years to travel from a distant galaxy and strike the sensor of the Hubble Telescope is, from its perspective, 'everywhere' along the path at once. It has 'always' been just created in a star, just leaving the star, just leaving the galaxy and just striking the sensor in the Hubble Telescope.
(Technically the only thing that has physically changed about such a photon is that its wavelength has increased due to the expansion of spacetime itself. So you could sort of say that a photon could 'sense' the passage of time if it could 'notice' that it was 'born' as a gamma ray and then 'became' a radio wave when it 'died' by striking the sensor of Hubble. This is analogous to what would happen if we travelled at near light speed to Alpha Centauri. By Special Relativity, a space traveller would feel no change in time on her ship but would notice that time on Earth was moving incredibly fast. Depending on her speed, she would notice that 'daily' updates from Earth were arriving at her ship every few seconds; and that after a few hours on her ship, her grandkids on Earth had died of old age.)
Let's assume for a moment that we invented a way to turn people and their spaceship into 'negative matter' that was immune to the light barrier and set them into space to travel to a planet orbiting Alpha Centauri. What would be its maximum speed? Let's assume NASA is very impatient and wants the crew to arrive at the target planet as soon as possible to start gathering close-up data. To achieve this, the crew sets its speed to reach Alpha Centauri in one second of their time as judged by their onboard-chronometers. However, the crew still faces the same problem faced by their positive energy counterparts travelling at near light speed, but much worse. In the one second it took the ship to reach Alpha Centauri there would be no Alpha Centauri. It would have burned out within the first micro-second the ship left Earth.
Under Special Relativity, your sense of time is unique to your reference point, or more precisely your acceleration in relation to light speed. So even though our space ship is throttling toward Alpha Centauri at a speed of 5 light years per second, Alpha Centauri is still operating according to its own clock, not the space ship's clock. And according to Alpha Centauri's clock, in the one second that the space ship takes to reach Alpha Centauri, according to Alpha Centauri's clock the star will have exhausted all of its nuclear fuel, turned into a red giant, then a white dwarf and then into a tiny, cool, dark husk of itself. So when the crew reaches Alpha Centauri in one second by its shipboard clock, there is no Alpha Centauri to see.
The key problem here, and the revolutionary concept embodied in Special Relativity, is that time is not constant for all observers. While it might seem to a ship crew at near light speed that only a day has passed, time is moving at a much different rate for those not travelling at near light speed, including the stars they are travelling towards, just as it is at NASA.
The problem of faster than light travel is one of simultaniety. In our Universe, simultaniety cannot exist because if it could, everything would have long ago happened at once. To have 'anything' happen that is less than 'everything' there needs to some manner in which somethings happen before other things and some things happen after other things. Without this basic precept, cause and effect could not exist. Cause and effect would be the same thing because everything and anything happened at once. Physical laws, which depend on cause and effect, could not exist. Everything would be indistinguishable from nothing.
So to have a 'space' between any two events, or to even have the concept of one event and any other, there has to be a temporal separation, ie. time. To have something rather than nothing, to have anything other than total simultaniety, there has to be a barrier to simulataniety. If we can be anywhere instantaneously, then we are always everywhere at once which means there is no 'here' or 'there.' At a practical level this would make fusion impossible, since there has to be two hydrogens which at some moment stop being two hydrogens and become a helium atom, releasing energy as photons. While a photon created in a star 10 billion years ago 'thinks' that no time has passed since its moment of creation and its striking the Hubble Telescope sensor, we know from our frame of reference that time has indeed passed and we can measure it. Without the unique time frames required by Special Relativity for each observer, the Universe itself could not exist. It would be a uniform, theoretical mathematical point. It would be simultaneously everything and nothing.
What I like about Special Relativity is that it states the passage of time observed by each unique observer is 'true' to them. With this axiom, our perception that a photon took 1 billion years to travel from a distant galaxy to us on Earth is as equally true as a photon (or a human space traveller who is travelling a near light speed) saying the trip took "no time at all."
The difference between us and a photon is that our as-fast-as-light-speed trip is basically meaningless unless we can communicate information about our trip to our friends who are poking along on Earth at a tiny fraction of light speed. Photons don't have to be concerned with this minor detail. We do.
One of the most important discoveries of recent astronomy is that we can optically view and study stars and galaxies as they existed hundreds of millions and billions of years ago, up to a few hundred million years from the birth of the Universe. And what we have found is that the same physical laws that govern our life on Earth today hold true in these extremely distant and past worlds, and therefore, in the earliest observable history of the Universe, long before the Earth and Sun were even formed.
So for faster than light travel to exist today, we would have to discard the most basic elements of Special and General Relativity, and by extension, most of all basic physical laws as we know them. We would have to tear everything down we know and start from scratch. This is not like saying that Einstein's laws of relativity replaced Newton's laws of gravity and motion. In contrast, Einstein affirmed and built upon the fundamental premises of these laws but refined them to accommodate special cases never observed on Earth except at extreme microscopic and megascopic levels.
Faster than light travel would require changes in the basic laws of physics on the scale of saying that rocks in your garden can suddenly leap off Earth and start orbiting the Moon, that you can be born after you die and that water can suddenly turn to ice at 100 F and turn to chlorine gas at 110 F and that perpetual motion is a standard part of reality instead of an impossibility.
The ultimate test of 'faster than light travel' is not that 'something' can move faster than light, but that humans can do it, or at minimum, that we can harness it to do useful work. Theoretically, humanity could meet all of its energy needs forever by harnessing the intense heat in the Earth's mantle and core. This could be done by drilling a lot of very deep holes, pouring water down them, turning it into steam and using the steam to turn electric turbines. Nothing stops us from doing this now except we lack the technological ability to do it. No basic physical laws need be broken to do this; in fact such a program is completely consistent with all know physics.
Faster than light travel requires all of our basic physics laws to be completely wrong. Faster than light travel would require the existence of something called 'negative matter' which no physical law even allows to exist; let alone intelligently harnessed so it could interact with us, who are not made of negative matter. Just to accelerate a single proton up to the speed of light requires more energy than exists in the entire Universe, unless all of our physical laws are completely wrong.
Faster than light travel would require us to finish something before we started it. It would require us to discard an invention before we invented it; to perfect it before we designed it; and to design it before we thought of it.
Even if we could cheat the laws of physics to travel 1,000 light years in a day, the result would be that the place we visited would be 1 million or 100 million years older than when we left. While our trip only seemed to us to take a day, for the place we visited, 100 million years would have passed since we set our course and started up our faster than light engines. Answering faraway distress signals, as typical on Star Trek, would be problematic, since their time would not be the same as ours.
The only way we could do a Star Trek styled "warp" without these Special Relativity effects would be to literally shrink the distance between our ship and our destination so that it was just a few hundred miles away. Only by doing this could we eliminate the huge differences in time reference between us and them. To travel to Alpha Centauri in a day, we would literally have to 'pull' Alpha Centauri to within a few million miles of Earth, or Earth to within a few million miles of Alpha Centauri. We would have to make disappear all of that space and matter in the 30 trillion miles of space between us and Alpha Centauri. We would have to shrink the fabric of the Universe itself, just as if we landed on the Moon in 1969 just by pulling the Moon and Earth so close we could travel to the Moon by helicopter.
Even if we could do this, we would destroy the Earth by doing it. By removing all of the distance between us and the Moon to make it easy to get there, the Moon would have to crash into the Earth and destroy it. You can't make an object close to you so it's easy to get there without having to deal with gravity. So now we'd also have to invent a way to make the Moon and Earth's gravity temporarily disappear until we 'pushed them back' to their original orbits. This is all the stuff you would have to do by radically shortening distances while keeping time constant.
It's one thing to shorten the trip from Boston to London from sail boat (a couple months) to 6 hours (a jet airplane) to fractions of a second (radio) because all of these improvements are below light speed. But to travel faster than light we have to do much more. We have to break every law of physics and have to account for every consequence of all the physical laws we need to break. We don't have to break any physical laws by building a faster boat or a faster plane. All of these improvements are allowed and encouraged by the same laws that govern the Earth, Moon, Sun and the planets and the entire Universe.
To make outer space fiction possible, writers had to treat the laws of physics as if inventing a ship to go faster than the speed of light is the same as inventing a jet airplane to replace a sailboat. But it's not. The laws of physics do not prohibit a jet airplane, in fact they encourage it. But they do prohibit any ship, even one as small as a single electron, from travelling at the speed of light or faster. This is a problem.
In a way, wanting to travel to Alpha Centauri in less than many many decades is like saying I want to grow gills and swim the oceans next week. At least the latter doesn't require all physical laws to be invalidated. It just requires a ridiculous, but still theoretically achievable, rate of evolutionary change in our bodies.
Wanting to travel to Alpha Centauri at faster than light speed is far more crazy and violent to physics than saying I want to be able to someday evolve to live in a total vacuum and 'swim' to the Moon naked. There are examples of a very few simple microbes that have survived in the total vacuum of outer space (they basically go into suspended animation) as long as they were shielded from the hard blast of UV radiation from the Sun. This extreme survival is allowed by all known basic physical laws. Travelling at the speed of light, or greater, requires all these laws to all be completely wrong.
This is a difference of type, not degree, like saying that in the future, with additional research, we will find that a triangle is a square.
1. In special relativity, your mass as you approach light speed is m = gamma(m) where gamma is a coefficient that equals 1/(√(1-v²/c²); where v is your speed and c is the speed of light. At half of light speed your mass would increase 1.15 times; at .999 light speed, your mass would increase 223 times. At v=c, your mass becomes infinite: ie., 1/√(1-1/1) = 1/√0.
2. At near light speed, time slows down for the traveller from the viewpoint of an observer at rest by T = gamma(t); with gamma again being 1/(√(1-v²/c²). At v=c, T becomes infinite. Another way to say this is that from the perspective of a traveller at near light speed, the clocks of everyone else move incredibly fast.
3. As David Griffiths notes in Introduction to Elementary Particles, (Wiley & Sons 1987), without the time dilation required by special relativity, cosmic ray muons produced every day in Earth's upper atmosphere would never reach ground level.
4. This is kind of an equational artifact due to special relativity being a subset of general relativity and energy being equivalent to mass, but is still fun to mess around with.
5. A saving grace for physics is that at least we can still wrap our heads around the intuitive idea that different forces operate at different distances. We don't have to worry about a refrigerator magnet sucking all of the iron atoms from the hemoglobin molecules in our red blood cells when we pour a glass of milk. For the same reason, we don't have to worry about 'dark energy' suddenly expanding the space of the Universe between our hand and the refrigerator handle and making the refrigerator 10 billion light years from us. Although this does seem to happen when we're out of milk.
Saturday, January 22, 2011
My baby boy Big died Thursday night. He was a turtle. A yellow bellied slider turtle. I have taken care of him for the past 16 years. He was in some troubled straits due to pneumonia this fall but he fought back and recovered. But then he suddenly died overnight this past Thursday evening.
I don't know much book larnin' but I do know that all atoms larger than lithium were made in the furnaces of stars. So Big and I are made of star stuff, welded from supernova billions of years ago and millions of light years away. Our atoms happened to coincide and combine in a tiny corner of the Universe and took on the character we call life, and through an inconceivable numbers of coincidences, we met in 1995 and formed a relationship.
Like all people grieving, I am struggling for answers to the horror and sheer blankness. I have none that are good -- who can -- but a dead guy, Carl Sagan, provides something that is comforting and as irrational as it is rational. As proven as it is unproven. And at least not gin-soaked with lies.
It is the Greek word Cosmos. It means all but it also means every one of us, from the smallest to largest. Nobody knows who will be the tiny shrew who becomes the first mammal or if mammals will evolve at all. Nobody knows who will be the slave who becomes King or the King who disappears into oblivion. Except for random events we could all be highly intelligent yet fascist Trilobites now.
But while I do hope there is still the Soul of Big, the Turtle, and I hope Big is now touring the Cosmos aware and alive mentally, I doubt that just as much as I doubt the same is happening with my Dad, who died in 1996. As much as I'd like to believe my Dad is flying around the Cosmos alert and talking on his CB radio and writing newsletters, I get the feeling that's not the way it goes. Nor for Big either. Or Big in the Big Aether.
Upon Death, we re-enter the Cosmos as primordial atoms and molecules from which we sprung. Like a a very abrasive skin scrub that takes away your whole body. By re-entering the Primordial Stew as non-conscious carbon atoms, we still remain just as much of the stuff as all our ancestors and ancestors and ancestors. In this sense we become one with our mothers the earliest bacteria. It's just that we don't see a violet light and shake their hands and hug and ask what's for dinner. But in a sense we do. To hug your bacterial mother you sort of have to be reduced to simple carbon molecules, or you'd not even recognize her.
All history is oral history since libraries are usually burned down if only for spite when they are preserved well. So just by writing this Epiphany to Big, the Turtle, I am making him in a small way more immortal than he would be otherwise.
It's the only thing the living can do for the dead.
Bye Big. I loved you.