Knightfall
World of Kulan DM
A friend on mine just sent me this link...
http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2007/08/06/nlevitate106.xml
http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2007/08/06/nlevitate106.xml
Mystery of levitation 'solved'
- Thread starter Knightfall
- Start date
freyar
Extradimensional Explorer
paradox42 said:
They'd have to rewrite most all of physics to do that. I'd have to read the actual paper mentioned in the linked article, but my professional side is a little suspicious about this. Also, note that the picture they show in this article looks an awful lot like a magnetic top.
freebfrost
Explorer
Actually, only on the Classic (i.e.Einsteinian) side of things. Quantum physics certainly allows for this kind of effect, as the forces at that level are barely understood even today.freyar said:
freyar
Extradimensional Explorer
freebfrost said:
Well, to be blunt, not really. Energy is conserved in quantum mechanics, as well as classical mechanics. You might be thinking of the uncertainty principle, which in some way lets certain processes "borrow" energy (though this is not really quite the best way to think about it). However, if you get an energy E for free, it has to go away in a time t, where E*t=h. h is Planck's constant, which is incredibly tiny in any units meaningful for talking about energy on a human scale.
freebfrost said:
Okay, two things.
First, QM only allows this sort of thing for very short times. You can borrow a bit of energy, yes, but you have to pay it back, and soon. There is as yet no evidence that the laws of thermodynamics can be violated wholesale.
Second, your wording suggests that somehow things are allowed to happen because we don't understand what is going on. That's wrong on two levels - physical reality, as yet, seems to operate no matter how well we understand it. Either the thing is allowed, or it isn't, either it happens, or it doesn't. How well we understand things is irrelevant to whether or not it happens.
On another level, I have to gripe at the "barely understood" thing. That's a flag often waved, but it isn't nearly as true as folks like to state. It seems like folks somehow talk about it as if it were digital - either we know everything, or we understand almost nothing. Folks who work in the field, however, recognize that we understand a whole lot, and that still leaves lots of room for new knowledge.
There is an argument that goes "we don't know how much we don't know, so what we don't know must be huge, and therefore what we know is insignificant". That argument is logically flawed, and should be ignored.
freyar
Extradimensional Explorer
Umbran said:
As one of those who works in the field, I'd say you're precisely right. In particular, this kind of question (can we get free energy from somewhere?) is one that we understand quite well. There are some people who every-so-often try to sell a "free energy source," but they're always shown to be cons.
tzor
First Post
Umbran said:
That's only because lawyers haven't gotten to really study QM. I'm sure some lawyer will find way to borrow energy, declare bankrupcy so they don't have to pay it back, find a way to restore their quantum credit rating and borrow again ad infinitum.
In the end it's kind of pointless. You really don't need free energy, you just have to be able to use all the energy we waste that's all around us. Energy? You're soaking in it!
physicscarp
Explorer
Here's a question about the Casimir force that struck me recently:
If the Casimir force is caused by lower density vacuum fluctuations, and the force causes two parallel plates to move toward one another, then where does the energy come from to do the work on the plates?
If it comes from the vacuum fluctuations, then there needs to be a corresponding decrease in energy elsewhere in the system. I'm seeing this explanation as analogous to Hawking radiation along the event horizon of a black hole, where the production of the radiation causes a mass evaporation effect on the black hole. I've been digging around the archives, but haven't found anything that satisfactorily explains this. Any thoughts from our other resident physicists?
If the Casimir force is caused by lower density vacuum fluctuations, and the force causes two parallel plates to move toward one another, then where does the energy come from to do the work on the plates?
If it comes from the vacuum fluctuations, then there needs to be a corresponding decrease in energy elsewhere in the system. I'm seeing this explanation as analogous to Hawking radiation along the event horizon of a black hole, where the production of the radiation causes a mass evaporation effect on the black hole. I've been digging around the archives, but haven't found anything that satisfactorily explains this. Any thoughts from our other resident physicists?
freebfrost
Explorer
Nor was there evidence of gravity prior to Newton, correct?Umbran said:
Our experience with reality is bounded by our current perceptions of reality. We can only attempt to prove what we know - we can't prove what we do not yet know. Heck, we still can't explain gravity.
"As yet" was also revelant to geocentrists prior to Copernicus.
Are you asking me a Schrodinger's Cat question here? That's perhaps the best example I can give, because scientists today cannot answer that question without a number of their own theories and interpretations. Which one is right?
Which one do you believe is right is perhaps the better question.
Can you say with any confidence that we understand 90% of how the universe works? Is the value 75%? 50%?
Our knowledge continues to increase at significant rate, yet we still have unanswered questions. It's easy to say that it is a flawed argument that knowledge is boundlessly large, but do you *really* see us having all the answers in the next 2/5/10/100/1000 years? It's possible, but I don't feel that its probable.
