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Solar Sail Will Work, says Planetary Society
degauss writes "In response to Cornell Physicist Thomas Gold's paper declaring the theroy behind solar sails flawed (previously mentioned in this Slashdot article), Louis Freedman, executive director of the Planetary Society (the organization behind the COSMOS project), has written a brief rebuttal to the claims in Dr. Gold's paper regarding the feasibility of solar sails for use as a method of transportation in space. He does not go in to detail with equations and such, but does give an overview of the reasons he believes Gold's hypothesis is incorrect."
There is a simple, yet somewhat expencive, way to see who's right.
Built a satelite / spaceprobe with a whopping huge and light (mylar maybe?) sail. Launch into space (as the sail will be then main experiment on this one, it can be relatively light and might piggyback anotehr launch). Deploy sail. Wait and see what happens. THEN one can sit down ans find out if current theories are on the mark.
Everything in the world is controlled by a small, evil group to which, unfortunately, no one you know belongs.
I have learned to use the word 'impossible' with the greatest caution.
To make laws that man cannot, and will not obey, serves to bring all law into contempt.
--E.C. Stanton
Well, if you're travelling to the outer solar system, you better not be in a hurry, no matter what your means of propulsion!
this alone calls into question Dr. Gold's ability
Depends on when he did this "seminal work on the steady-state theory". I'm in my 40s, and I remember when it was still considered acceptable to have some reasonable doubt about the big bang. If he's in his 70s, and did this work, say, 50 years ago, it's possible that the work was considered completely solid at the time. And the word "seminal" does imply that it was a while back.
I'm reminded of Stephen J. Gould's defense of the Bishop of Usher (the one who determined that the universe was created in 4004BC). Looking at that date based on what we know now, it's easy to assume that he was a religious fanatic, but if you look at what was known at the time he did the work, it turns out that he actually did some pretty solid scientific research to come up with that date. The fact that he was working from a set of bad assumptions was not really his fault.
So, back to Gold, if he's still a proponent of the steady-state, then he can probably be dismissed as a quack, but the fact that he once worked on the theory doesn't really say anything one way or the other.
As silly as the steady-state theory may be, I think that it's impossible to gauge the value of any truly scientific theoretical work. And I wouldn't judge the ability of any scientist by the subject or direction of their work so much as by the way in which their work is conducted.
The actual theoretical work done in exploring the logical space of any theory, accepted or idiotic, can have a value entirely independent of the value of the theory itself. I am not familiar with Dr. Gold's work, but I would not dismiss it or his ability because it was done in support of a theory that most people now regard as inferior. For one thing, no real scientific work is ever done solely in support of a theory. One may have certain hopes about the way an experiment might turn out, but we test hypotheses by attempting to find instances of their falsehood. If Dr. Gold's theoretical work involved accurately describing the state of affairs of a steady-state universe, then his work should not be demeaned simply because the theory it describes is no longer accepted as "the way things really are". All theories are models and are by definition imperfect analoges of what they model. Even if we could be sure that a theory is perfectly isomorphic in structure to what it represents, there is no way to be certain of its predictive ability for any length of time.
The work done to describe a solar system of which the Earth is the center may not have described the way things really are, but without it there would be no reason to seek the simpler description (Thank you, Copernicus) that we now use to calculate the past and future positions of celestial bodies.
There are many reasons that theoretical work can have value that are independent of the theory with which the work is concerned. I woudl take the same attitude as Gold's former student in thanking him for stimulating the scientific community.
"Science is the belief in the ignorance of experts." - Richard Feynman
Though no idea should be dismissed a priori in science, this alone calls into question Dr. Gold's ability. Unless they're using "steady state" in a manner unconnected to its traditional usage, Dr. Gold is on the side of a theory that has pretty much fallen by the wayside. Excluding the increasingly, um, eccentric Fred Hoyle, there are no real leaders among the handful of proponents of steady state.
The word "seminal" means "containing seeds of later development." The article makes no mention of whether or not he still advocates (or ever advocated) that theory. It only stated that his work was important for its development.
Also, keep in mind that many brilliant minds have dabbled in what we now consider quackery. Issac Newton, for example, was interested in alchemy and biblical chronology. Yet he still managed to develop his brilliant theory of gravitation.
Does this
I'm sorry, but no. I've not read Gold's work or even heard of him, but I read a number of Hoyle's papers. In the early 1950s, steady state was a perfectly respectable theory with a few minor bumps from observations (such as the Hubble expansion). In the subsequent 50 years, the observations have gotten much more rigorous, much more extensive, and much more valid. They have also become much, much, much more difficult to explain via steady state. Fred Hoyle -- admittedly once a great astronomer -- has become increasingly shrill and outlandish in his theoretical constructs designed to explain the "illusion" of the cosmic background radiation.
You're entirely right that the merits of a scientific position ought not be dismissed due to the personalities of the people who hold it. But equally true is the statement that no scientific position ought to be elevated merely because some proponents once did good work, in a different subdiscipline.
The Mongrel Dogs Who Teach
Actually at the earths distance from the sun the power output of the sun per unit area is about
1400 W/m2. The sail on the COSMOS spacecraft is about 1km2 and the total weight of the thing is about 1kg.
The force works out to be about 9N, and so the accelaration to 9m/s2. This is slightly less than the acceleration due to gravity.
If you jump off a bridge you should find that you accelerate to 100mph quite quickly.
:wq
The main practical difficulty I see is stopping. You can't slap propelled rockets on the ship to do the job; if you did, I would want to know you didn't propell you ship with that to begin with.
Presumably you'd want to travel to another solar system. In that you'd set the sail in the other direction as you get closer.
Moreover, we wouldn't get very far away, because the force provided by sunlight diminishes exponentially as you move further away.
Rubbish. You are accelerating the whole time it takes you to leave the solar system. Just because you stop accelerating after that doesn't mean you stop. And the force acting on the sail drops off as 1/d*d which is polynomial, not exponential.
And going towards another star wouldn't help, because you can't sail against the "wind" in this case
You could collapse the sail.
We're getting to the point where it will just take too long to go where we want to go, and eventually it's going to make us ask if we really can go there. I mean, hundreds of years later, who's going to care that a probe, unable to communicate with us, is careening somewhere past Neptune? As for people, don't hold your breath on this transporting us; it just takes too long. I don't know about you, but going to another planet wouldn't be worth most of my life, if not the whole thing and part of my children's.
Not everyone is like you. (the kind of person who would sit back and say "impossible, the earth is flat" as Columbus sets sail.) I am kind of proud to think that the two Voyagers (both of which are still sending data) are out past Neptune. And the physicists who study the heliopause and the inter-stellar medium still find their data useful.
:wq
6. Apply for a patent. You will get the patent, is too easy these days.
/. crowd. Yes, when it comes to SOFTWARE patents the USPTO is f'n up feircely.
What bothers me here is that are trying to drum up karma by catering to the USPTO sucks, and lawsuits suck
Solar sail technology is legitimately patentable even though it is gritting on the nerves of those who have not made a considerable investment in the development of anything ever.
Readers and contributers to this site seriously need to learn that it takes capital investment to drive an economy. I can not understand how some people complain of an economic slump, specifically in the IT sector, and in the same breath make outrageous claims like software and information should be free.
Yes, SCO sucks. I know. They do, and I'm sick of reading out them. But remember, there are people there who are going to lose their jobs.
If you invested millions into a technology nobody else has wouldn't you like some guarantee that you have the ability to return the investment?
The List of Grievances with Slashdot.
... would be to ask him to explain how comet tails form. Doh! I have to admit not even thinking of that when I read Gold's article.
Freedman's rebuttal says that Gold is wrong to argue from a thermodynamic point of view, and that he ignores quantum mechanics. However, all the laws of physics must be consistent with each other. This consistency is what makes these intellectual arguments so interesting. For example, by insisting that electrodynamics was consistent with mechanics, Einstein developed special relativity.
Gold's arguments are simply wrong, but this incorrect rebuttal is not really that good. When debating with crackpots, it's important to be meticulous in your arguments, because they will seize upon any small error and attempt to make that the focus of the debate, not their own large, glaring errors.
It's not wasting time, I'm educating myself.