For you physics buffs out there.
ElectricAye
Posts: 4,561
An interesting perspective on physics. I wonder if looking at physics this way would motivate physics students to break new ground or cause them to slink away in disillusionment?
http://www.americanscientist.org/issues/pub/the-man-behind-the-curtain
http://www.americanscientist.org/issues/pub/the-man-behind-the-curtain
Comments
By the time you get to uni this separation of "theory" from "reality" in you mind should be second nature.
I have to say in my case though things got so complicated for me that sometimes I could not make that separation. I could not tell if I was failing to understand the maths theory or having a doubt about the reality of it all.
So perhaps, as the article implies, it would have been better to have the Profs wave some red flags occasionally to indicate that "If you are having trouble understanding this it's because there really is a hole in our understanding, it's not your fault"
When I was a senior I would attend talks given by the professors on their research. They would debate the latest models that were being developed that tried to explain the new sub-atomic particles that were being discovered at the time. I realized at that point that the field of Physics only described the superficial stuff that we observe, and it was struggling to describe the basics of matter, space and time. It was about that time when I became more interested in computers and engineering than I was in Physics.
I think that to the extent that realism is swept aside, the allure of dedicating one's mind to the pursuit of physics is diminished, but to the extent that it's embraced and sought after, great minds will pursue the quest. In other words, teach that the weirdness, and the accompanying reliance on formalisms, is merely a transitory stage in our journey, not the mind-numbing dead-end destination.
Can't solve your problems in 6 dimensions? No worries! Just tack on another dimension.... and another.... and another.... and...
http://www.amazon.com/Trouble-Physics-String-Theory-Science/dp/B004Z4LYU2/ref=sr_1_1?s=books&ie=UTF8&qid=1307721265&sr=1-1
We did have labs where we shot steel balls a different angles. We were supposed to compute where the ball would land at various angles after a couple of calibration shots at one angle. The computed and actual distances where pretty darn close.
Physics can be used to solve all sorts of problems. I fear there is an anti-science trend in going on in parts of the world. I hope the above mentioned article doesn't provide fuel for the movement.
Just don't start teaching intelligent design because there are still limits to what science understands. (Not that the author was suggesting this.)
I either had different text books and teachers than the author or we interpreted what was taught differently.
Duane
I think that math is likely something the human brain can do as a result of its design. However, our brain is designed to deal with the physical world on our scale. So it doesn't seem all that odd to me that it falls over with conditions outside of our normal experience. I actually find it more surprising that we're able to grasp any information about it at all.
That's pretty funny. While I've never had the privilege of working without friction, I know from experience that vacuum environments really suck.
It was my Physics teacher, seeing things that interested me in astronomy, recommended Relativity courses. I took his advice and it was world changing and eyes opening. By then I was planning to build a telescope large enough to see out to the edge of the Universe. (I did, but that's another story)
I remember how it opened up a new Universe and the great excitement of discussions we had about time travel, matter-antimatter, Lorentz Contraction, and the possibilities of faster than light travel (the i equation). Looking back, the jump from Newtonian mechanics to that of Relativity was spectacular. Today we're looking at more physics that goes beyond relativity.
I would highly recommend the same path.
Very funny. Static electricity can be a sticky subject, and the subject of astronomy is looking up. Please don't tell me, "Astronomers do it at night." I got ribbed by that one all the time...
I do have a physics question that my professor was not able to adequately answer:
You are an astronaut in space, and you are holding in your hand the end of an infinitely long massless rope that goes off into the distance. You give the rope a single 'up-down' pulse relative to your body. What motion do you (the astronaut) go through?
I would say your center of mass doesn't change since there is no mass acting against you. Your body moves down when your arm moves up and vice-versa.
I think SRLM was probably poking fun at massless ropes. Pulley problems often had massless ropes to make the problems easier to solve. Such simplification can be very helpful and often your answer is close enough to do useful engineering.
If you're wondering whence the energy of the pulse goes as it travels down the rope.... hmmmm, I'm guessing that "real" ropes get modeled as assortments of springs and masses, so in the case of a "real" rope, the displacement of the pulse travels because the masses oscillate thanks to the multitude of mass-spring interactions. But in the case of your massless rope, the pulse is probably not going to travel down the rope, no energy will be transferred from the astronaut (you) to the rope, so you might wiggle up and down temporarily while wiggling your fist, but as soon as you stop moving your fist, you are right back where you started. I think a real rope needs mass to propagate a pulse.
Farmer Bob's chickens stopped laying eggs, and he couldn't figure out why. He tried everything. He called a vet, and the vet couldn't figure it out. He got a doctor and she just shrugged. There was a university nearby and he got everybody -- biologists, chemists, even some anthropologists to do a shamanic dance. Nothing worked. Finally, it being the field furthest from his problem, he got around to asking a physicist to look into it.
The physicist measured the farm yard and within five minutes announced that he knew the problem. Farmer Bob was astonished. "How could you? Everybody else came up blank."
"It's simple," the physicist said. "First, you assume a spherical chicken..."
I believe the disjoint here is that physics n00bs are taught that the equations of physics drive the universe, that these equations are prime movers that describe an underlying reality. But that is not the case, and in fact if you think about it much it obviously isn't the case. What equations do is describe the universe, the bulk behavior and (less accurately) the individual behavior of its swarms of particles. Because equations work so well and often I do think a lot of physicists are seduced into missing this.
For a very simple example, consider the problem of what happens when you roll dice. There is a very simple equation which describes the distribution you will get if you roll two dice and record the result over and over. You can derive that equation from the number of sides of the dice and the possible outcomes. It might be tempting to say that equation is what makes dice work.
But you can do a simulation of dice, using an entirely deterministic computer programmed with an entirely deterministic random number generator, and if you run this gross approximation that has the equation nowhere within it the results of the equation will quickly materialize. You don't even need real dice that do a full simulation of the real ones; crude fakes give the same result.
Although it's widely considered a conceit and a side show that hasn't produced any real results, the greatest mathematical advance of the 20th century was the discovery of chaos and fractal expansion in the 1980's, because this is the math that really does describe the universe. Fractals produce systems that look real in exactly the way that frictionless springs and perfect vacuums don't. The problem is that while fractals probably explain how the universe works a lot better than equations, they aren't very predictive, except in the sense that in some cases, such as the weather, they predict that there is no possibility of prediction at all. Physicists tend to regard this as an unuseful result although it really is useful if it tells you when to stop throwing money at something that can't ever work much better than it already does.
The implication of fractal math is that the universe really is something much more like a computer than a field of perfectly interacting billiard balls, and this also suggests that like a computer it might allow for exceptions and shortcuts of a sort one wouldn't expect from simple particles. It also suggests a very different interpretation of certain things physicists take for granted; the Heisenberg Uncertainty Principle is a nice fundamental thing, but it's also the kind of thing that might emerge if the universe has a discrete resolution. But it turns out that this resolution can be spent on either velocity or position, which might be an interesting clue as to how the Big Computer is programmed...
If the speed of a wave is infinite, and the length of the rope is infinite, then which infinite is "bigger"? How could we compare them, mathematically? It probably doesn't have much application (a really long piece of spider silk in space?) but it's interesting to think about...
But ok, say the rope wasn't massless and we have the following:
You are an astronaut in space, and you are holding in your hand the end of an infinitely long rope of unit mass small relative to yourself, and the rope goes off into the distance. You give the rope a single 'up-down' pulse relative to your body. What motion do you (the astronaut) go through?
(EDIT: I'm wondering if the original equation assumes that the rope is under tension. If so, then how could an infinite rope ever be under tension? It has no mass, therefore it can't be "anchored" to its own inertia. And it doesn't have an end, so it can't be tied to anything. )
In any case, if the rope does have mass, then I think it will require energy to stretch the springs (in my presumed mass-spring model), so I think you ( the astronaut) would still wiggle back and forth but not at the same amplitude as you would if you were just waving your fist up and down. I think the rope would act as an energy dump. But don't take my word for it: I obviously don't know what I'm talking about.
But what is the action? Sure, your arm goes up and down, so let's say that cancels out. But haven't you put energy into the rope for the pulse? Or would that cancel out too because everything is floating?