Oh, good, I really was hoping my OP would get eaten. Let’s try again.
This requires some introduction, first. I run a bunch of MOOs (online multiplayer text-based games) which have acquired a rather diverse group of players. In the middle of a (semi) rational discussion on our message board, one of these players suddenly takes it upon himself to reject the possibility that an object can propel itself in space without some matter present to “push against.”
The discussion gradually degenerates from there. Eventually, he pulls the “righteous crusader” bit and decides that we’re wrong because we aren’t questioning the evil physics establishment. Sigh.
The thread is here. The physics discussion starts a bit more than halfway down on page one, with takama’s fifth post.
I figured some of you might enjoy reading this seemingly hopeless fight against ignorance, and perhaps even step in to help if it doesn’t get resolved soon. I’m sure there are plenty of people around here who can explain this stuff far better than I can.
I’m just a lowly english major here, but I was under the impression that without something to push against, an object couldn’t go from 0 mobility to .000000000001…
Ermmmm…I was under that impression too. that’s what I learned in the mecanique section in my physics class.
However, space is not “full of void”. It has lots of small (and big. IE: planets, stars,meteors…) particles. Which is why even if we could reach the speed of light, the friction of the ship against those particles would heat it so much it would blow it up. But wait… that’s stupid because you can’t get the absolute speed of light if there is anything between you and your destination point.
you know what, i’m going to stop the slaughter here…hopefully someone will enlighten us all about this topic.
Exactly, Gozu. Things can’t (if I remember right) move without nothing to push on them. But even in the void of space there are particles to push against. And you can always push against something like fuel, which (it was my understanding) is how part of space travel works.
Someone ought to teach that takama person the difference between mass and weight. Because unless that rock is becoming physically smaller its mass ain’t changing. Its weight, however, is.
I think.
And if Exile isn’t already a doper, he sure has the mind of one.
"does a lack of knoladge(danm i wish i could spell) make a man unintellegent.
who cares how smart you are. that doesnt show if you are intellegent"
There are too many gems in that thread. The only thing I can say is that guy does not know how to argue from a scientific perspective at all. Holy shit. I thought some GD arguments got people misunderstanding. That guy … whew!
The stuff being thrown out of the back of the rocket is the stuff that’s being “pushed against”. Each individual particle that a rocket sprays out won’t do much to push back against a rocket (after all, it takes force to push that particle somewhere… where does that force go?), but multiply that by a trillion and you’ll start to get somewhere.
Ah, I just got through a “debate” with an email correspondant that took the form of:
Him: [Ridiculously inaccurate statement about astronomy based on a misreading of a fifty-year-old encyclopedia.]
Me: [Polite correction.]Him: Yes, but [Another ridiculously inaccurate statement about astronomy.]
Me: [Polite correction.]
Him: Yes, but [Another ridiculously inaccurate statement about astronomy.] So you see, all of astronomy is wrong!Me: [Polite correction.] And, uh, since I’m never going to convince you you’re wrong, and you’re never going to convince me that all of astronomy is wrong, let us end our discussion now, while it’s still friendly. Have a nice life!
[Can you tell that Poddy’s gone a few rounds with wackos in the past and is now a bit disillusioned?)]
Him: Yes, but [Another ridiculously inaccurate statement about astronomy.]
Me: [Polite correction.] I won’t be responding to your email anymore. Have a nice life!
Never fails to amaze me how many uneducated maroons figger that they have Seen Through The Lie, while the professionals are in error about the fundemental facts of how the universe works. I ‘spect it’s a form of mental illness. I always wonder whether the bulk of these people are actually able to function in society, or whether they’re all destined for the looney bin. (I did have one wacko correspondant who eventually revealed to me that the television contained hidden messages directed especially to him, and that the Queen of England had given him a special secret mission to build a time travel machine–and due to the freakin’ university directory that lets any one look up all your information using your email address, this guy had my home address. )
I’m not denying that takama is quite mistaken, but I think I might see the source of his confusion. Take these two facts:[list=1][li]Without friction, you would not be able to walk, because you need to friction to push against the ground.When you move through any medium, such as air or water, you encounter friction that you would not encounter if you were in a vacuum.[/list=1][/li]
Mush these facts together up, confusing friction with the ground with friction from the air, and conclude that it is friction with the air that propels you when you walk.
Virtually yours,
DrMatrix - A little knowledge is a dangerous thing.
