Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: syhprum on 02/12/2012 18:09:17
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I think they should start teaching special relativity in Kindergarten and general relativity in junior school as they seem to be the two subjects that cause the most confusion if this forum is anything to go by.
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If they can teach people that "if it looks too good to be true, then it's probably not true" it would make the world a better place too.
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Human life has time to complicate relativity. Time of human life is not sufficient to simplify relativity.
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It is an interesting postulate, Syphrum. I guess the fundamental concepts could be taught but it would be difficult to do properly without significant maths. I can't help but think it might all come out like a BBC Horizon program which, in my view, only "preaches to the converted" and conveys very little with its rambling, misleading artistic impressions and useless graphics. Maybe few people understand Relativity, and fewer still QM, because they are very hard and need a huge hinterland of knowledge (and probably a large degree of aptitude) to really get a grip on the subjects.
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I think they should start teaching special relativity in Kindergarten and general relativity in junior school as they seem to be the two subjects that cause the most confusion if this forum is anything to go by.
syhprum, would you like to see a cinematic only demonstration of the existence of an absolute speed, that is a speed which is invariant with the frame of reference? It's not difficult, it just need a bit of time to study it.
The demonstration requires the principle of relativity only (first postulate of SR) and is the following (please, forgive me for my bad translation into english):
We have two inertial frames of reference, K and K* (for example K could be a railway station and K* a train) in relative motion at velocity v > 0 along the positive x.
The coordinate transformation (x , t) -> (x*, t*) (t is time) have to be linear, since a uniform, rectilinear motion in K, is such in K* too.
The most general linear transformation is:
x* = A x + B t ( 1 )
t* = C x + D t ( 2 )
where A, B, C, D don’t depend on the coordinates but, at maximum, on v only.
According to ( 1 ) and ( 2 ) a signal (or an object) velocity in K* is:
u* = dx* / dt* = ( A u + B ) / ( C u + D ) ( 3 )
where u = dx / dt is the signal velocity in K.
Clearly,
u* = 0
u = 0
implies, respectively:
u = v since a stationary body in K* moves, in K, at v
u * = - v since a stationary body in K moves, in K*, at -v
so, for (3), B = - Av; B = - Dv, and so:
D = A
B = -Av
From which:
u* = ( u - v ) / [ 1 + ( C u / A ) ] ( 4 )
which can be wrote as :
u* = ( u - v ) / [ 1 - ( u v / F2 ) ] ( 5 )
where: F2 = - A v / C ( 6 ).
First case: F2 = infinite.
We get the galileian transformation law of velocities: u* = u – v.
Second case: F2 < 0.
We have to exclude it because, if it were true, a signal which has in K negative velocity u (that is from the head to the tailor’s train) and such that u < F2 / v, would have in K* positive velocity u* (that is from the tailor to the head’s train) and this is absurd since the impact of signal with the train’s head is an objective fact on which K and K* must agree (if the signal destroyes the train’s head, K and K* must agree on this destruction).
We are left with F2 > 0.
Since F has the dimensions of a velocity, we can imagine a signal which has velocity u = F in K. According to (5) the velocity of the same signal in K* is u* = F, that is is the same value F.
So, according to the couple K-K*, there is an absolute velocity F.
Conclusion: the existence of (at least one) an absolute velocity (finite or infinite, this can only be determined by experiment) that is, the fact light speed doesn’t depend on the source’s velocity, comes from pure cynematics, without using the second postulate of SR.
In the text: W. Rindler, Relativity (special, general and cosmological) 1977 edition, there is the proof that the absolute velocity F doesn’t depend on v.
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I often wonder that too, for a couple of reasons.
1) I think certain ways of thinking about the nature of reality became so ingrained in my mind (like feeling that time should be constant) that no matter what read now, I would never be able to break those conceptual habits, and I'm not sure even a better understanding of math would help. What would happen if you taught something like relativity or quantum mechanics to someone who didnt have years and years of "common sense" beliefs or Newtonian physics in their head?
2) In school I was taught science bottom up. Meaning first you learn the basic principles, memorize certain handy facts. I also memorized a lot of things, like, say, the steps of the Krebs cycle, that arguably didnt need to be stored in long term memory, because you "can look it up," if you need it, but being forced to do that did give me a lasting sense of "how things work." Anyway, learning science bottom up gives you a more solid foundation, but it takes so God awful long before you see the big picture and it starts to get interesting. I think a lot of kids get tired and bored before they ever reach that point. It's like you have to eat a lot of vegetables before you ever get dessert. I do sometimes wonder what would happen if science was taught top down, starting with interesting phenomena and working backwards to explain why it happens, but that might result in a lot of gaps and holes in knowledge or a more superficial understanding. But it does seem like science teachers, especially in physics, save all the "cool stuff" until the very end.
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When I took first year college Physics...
Hmmm...
They combined the lab activities for the Physics with Calculus and the Physics without Calculus courses.
Some of the COLLEGE students had a lot of troubles with the basic concepts of Newtonian physics...
If the average college student has troubles understanding Newtonian Physics... how can you imagine that a kindergarten student could understand concepts of light, waves, and relativity?
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When I took first year college Physics...
Hmmm...
They combined the lab activities for the Physics with Calculus and the Physics without Calculus courses.
Some of the COLLEGE students had a lot of troubles with the basic concepts of Newtonian physics...
If the average college student has troubles understanding Newtonian Physics... how can you imagine that a kindergarten student could understand concepts of light, waves, and relativity?
I once dated a high school teacher who asked me for help passing her math test for teacher certification. She didn't understand that you can subtract a larger number from a smaller number. Despite, refusing to accept my correction, she got her certification.
If we can't get people with basic first-grade math skills to teach high school, where do you expect to find kindergarten teachers with a basic understanding of SR?
Anyway, there's no point teaching SR until the students have enough math skill to solve the SR formulas. If you get a Doogie Howser brain home schooled by parents who happen to be physics professors, maybe they could prepare the kid to learn SR by the time he's 8 years old.
The best you an hope for in a public elementary school is for teachers not poison children's minds with garbage like, "You can't subtract a big number from a little one," and "Time is absolute."
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You'd need to be careful not to poison their minds with assertions that time is not absolute too.
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This was of course a rather tongue in cheek suggestion as the forum seems to weighed down with rather esoteric questions about relativity QM and other rather unanswerable question being a humble technician I like questions that have answers that I can address with my rather limited maths that don't need tensors and what not.