This gives us: t = Vd/1/2a
d is 30,000,000 miles expressed in feet, or 158,400,000,000. Set that into your pocket calculator. Divide it by one half of one tenth of gee, or 1.61. Push the square root button. Multiply by 4. You now have the elapsed time of the round trip expressed in seconds so divide by 3600 and you have it in hours, and divide that by 24 and you have it in days.
At this point you are supposed to be astonished and to start looking for the mistake. While you are looking, I'm going to slide out to the refrigerator.
There is no mistake. Work it again, this time in metric. Find a reference book and check the equation. You will find the answer elsewhere in this book but don't look for it yet; we'll try some other trips you may take by 2000 A.D. if you speak Japanese or German - or even English if Proxmire and his ilk fail of reelection.
Same trip, worked the same way, but at only one percent of gee. At that boost I would weigh less than my shoes weigh here in my study.
Hmmph! Looks as if one answer or the other must be wrong.
Bear with me. This time we'll work it at a full gee, the acceleration you experience lying in bed, asleep. (See Einstein's 1905 paper.)
(Preposterous. All three answers must be wrong.)
Please stick with me a little longer. Let's run all three problems for a round trip to Pluto - in 2006 A.D., give or take a year. Why 2006? Because today Pluto has ducked inside the orbit of Neptune and won't reach perihelion until 1989 - and I want it to be a bit farther away; I've got a rabbit stashed in the hat.
Pluto ducks outside again in 2003 and by 2006 it will be (give or take a few million miles) 31.6 A.U. from the Sun, figuring an A.U. at 92,900,000 miles or 14,950,000,000,000 centimeters as we'll work this both ways, MKS and English units. (All right, all right - 1.495 x 1013 centimeters; it gets dull here at this typewriter.)
Now work it all three ways, a round trip of 63.2 A.U. at a constant boost of one gravity, one tenth gravity, and one hundredth of a gee - and we'll dedicate this to Clyde Tombaugh, the only living man to discover a new planet - through months of tedious and painstaking examination of many thousands of films.
Some think that Pluto was once a satellite and its small size makes this possible. But it is not a satellite today. It is both far too big and hundreds of millions of miles out of position to be an asteroid. It can't be a comet. So it's a planet - or something so exotic as to be still more of a prize.
Its size made it hard to find and thus still more of an achievement. But Tombaugh continued the search for seventeen weary years and many millions more films. If there is an Earth - size planet out there, it is at least three times as distant as Pluto, and a gas giant would have to be six times as far. Negative data win no prizes but they are the bedrock of science.
Until James W. Christy on 22 June 1978 discovered Pluto's satellite, Charon, it was possible for us romantics to entertain the happy thought that Pluto was loaded with valuable heavy metals; the best estimate of its density made this plausible. But the mass of a planet with a satellite can be calculated quite easily and accurately, and from that, its density.
The new figure was much too low, only half again as heavy as water. Methane snow? Perhaps.
So once again a lovely theory is demolished by an awkward fact.
Nevertheless Pluto remains a most mysterious and most intriguing heavenly body. A planet the size and mass of Mars might not be too much use to us out there ... but think of it as a fuel dump. Many stories and many nonfictional projections speak of using the gas giants and/or the rings of Saturn as sources of fuel. But if Pluto is methane ice or water ice or frozen hydrogen or all three, as a source of fuel - conventional, or fusion, or even reaction mass - Pluto has one supremely important advantage over the gas giants: Pluto is not at the bottom of a horridly deep gravity well.
Finished calculating? Good. Please turn to page 368 and see why I wanted our trip to Pluto to be a distance of 31.6 A.U. - plus other goodies, perhaps.
11. 1950 Your personal telephone will be small enough to carry in your handbag. Your house telephone will record messages, answer simple inquiries, and transmit vision.
1965 No new comment.
1980 This prediction is trivial and timid. Most of it has already come true and the telephone system will hand you the rest on a custom basis if you'll pay for it. In the year 2000, with modern telephones tied into home computers (as common then as flush toilets are today) you'll be able to have 3 - dimensional holovision along with stereo speech. Arthur C. Clarke says that this will do away with most personal contact in business. I agree with all of Mr. Clarke's arguments and disagree with his conclusion; with us monkey folk there is no substitute for personal contact; we enjoy it and it fills a spiritual need.
Besides that, the business conference is often an excuse to loaf on the boss's time and the business convention often supplies some of the benefits of the Roman Saturnalia.
Nevertheless I look forward to holovideostereophones without giving up personal contacts.
12. 1950 Intelligent life will be found on Mars.
1965 Predicting intelligent life on Mars looks pretty silly after those dismal photographs. But I shan't withdraw it until Mars has been thoroughly explored. As yet we really have no idea - and no data - as to just how ubiquitous and varied life may be in this galaxy; it is conceivable that life as we don't know it can evolve on any sort of a planet... and nothing in our present knowledge of chemistry rules this out. All the talk has been about life - as - we - know - it - which means terrestrial conditions.
But if you feel that this shows in me a childish reluctance to give up thoats and zitidars and beautiful Martian princesses until forced to, I won't argue with you - I'll just wait.
1980 The photographs made by the Martian Landers of 1976 and their orbiting companions make the prediction of intelligent Martian life look even sillier. But the new pictures and the new data make Mars even more mysterious. I'm a diehard because I suspect that life is ubiquitous - call that a religious opinion if you wish. But remember two things: Almost all discussion has been about Life - as - we - know - it.. . but what about Life - as - we - don't - know - it? If there were Martians around the time that those amazing gullies and canyons were formed, perhaps they went underground as their atmosphere thinned. At present, despite wonderful pictures, our data are very sparse; those two fixed Landers are analogous to two such landing here: one on Canadian tundra, the other in Antarctica - hardly sufficient to solve the question: Is there intelligent life on Sol III?
(Is there intelligent life in Washington, D.C.?)
Whistling in the dark - I think I goofed on this one. But if in fact Mars is uninhabited, shortly there will be a land rush that will make the Oklahoma land stampede look gentle. Since E = mc2 came into our lives, all real estate is potentially valuable; it can be terraformed to suit humans. There has been so much fiction and serious, able nonfiction published on how to terraform Mars that I shan't add to it, save to note one thing:
Power is no problem. Sunshine at that distance has dropped off to about 43% of the maximum here - but Mars gets all of it and gets it all day long save for infrequent dust storms ... whereas the most that Philadelphia (and like places) ever gets is 35% - and overcast days are common. Mars won't need solar power from orbit; it will be easier to do it on the ground.
But don't be surprised if the Japanese charge you a very high fee for stamping their visa into your passport plus requiring deposit of a prepaid return ticket or, if you ask for immigrant's visa, charge you a much, much higher fee plus proof of a needed colonial skill.
For there is intelligent life in Tokyo.
13. 1950 A thousand miles an hour at a cent a mile will be commonplace; short hauls will be made in evacuated subways at extreme speed.