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Benny
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Re: various physics questions  
« Reply #50 on: Jul 12th, 2008, 3:11pm »
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I see your point. Thank you for taking the time and trouble to read the beginning of this nonsense.
 
It's funny that physics attracts more wannabes, crackpots than mathematics.
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Re: various physics questions  
« Reply #51 on: Jul 13th, 2008, 6:56am »
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on Jul 12th, 2008, 3:11pm, BenVitale wrote:
It's funny that physics attracts more wannabes, crackpots than mathematics.
I'm not sure whether that's true in numbers relative to the number of physicists and mathematicians.
For example, I recall there was someone a few years back that claimed to prove the cardinality of the sets of rationals and real numbers are the same. That's pretty fundamental crackpottery right there.
Of course, maths does have the advantages that you're not limited by reality (of course, one might argue theoretical physicists sometimes cross that line, like in string theory.)
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Re: various physics questions  
« Reply #52 on: Jul 13th, 2008, 7:42am »
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on Jul 12th, 2008, 3:11pm, BenVitale wrote:
It's funny that physics attracts more wannabes, crackpots than mathematics.

Anyone else remember James S. Harris?  Oh, and he has a blog too.
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Re: various physics questions  
« Reply #53 on: Jul 13th, 2008, 8:18am »
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on Jul 13th, 2008, 7:42am, Eigenray wrote:

Anyone else remember James S. Harris?  Oh, and he has a blog too.

Yeah, I've slagged him off a few times. LOL
 
Here is a list (not my own) of top cranks (mostly on sci.math), with reasons:  
 
1. Ben Jebara (ajebara) for linking the negation of the axiom of choice to infinite integer solutions of FLT using a Fraenkel-Mostowski model in which x.x.x.... exists for odd x but not for even x and in particular his observation that something that exists cannot be equal to something that doesn't.
 
2. Edgar E Escultura for discovering that only terminating decimals can be added and multiplied and that non-terminating decimals, including all the irrationals are ill-defined.
 
3. James Wanless for finding out that Goldbach's conjecture is false even though his counterexample was "rather large", for solving the twin prime conjecture and indeed the 2n prime conjecture (differing by 2n rather than 2) , solving FLT, an extraordinary proof of Pythagoras' theorem, proving no odd perfect numbers exist, solving Catalan's conjecture, solving Carmichael's conjecture, an amazing proof that between n and 2n there is always a prime, a hypershort proof of Dirichlet's theorem and a fantastic proof of the Collatz conjecture.
 
4. James S Harris for proving FLT about 2000 times in 3 years using only very elementary methods.
 
5. Tleko for discovering that f(z)=z is not analytic.
 
6. Sollog for discovering that the primes are not randomly distributed but actually fall into 8 of 30 columns and any number which doesn't can be absolutely excluded from being a prime and JP (who is probably the same guy) for advertising this and for proving his point by using capital letters.
 
7. Zhang Hong for solving the continuum hypothesis in a smart way.
 
8. Mike Deeth (probably) for pretending to be 11, to be called Nathan and for discovering that certain things simultaneously exist and do not exist and for introducing the revolutionary technique of making childish ancient jokes with the word Cantorian substituted somewhere to prove his points.
 
9. Archimedes Plutonium: his achievements are too many to even think about listing - with 25349 messages he had contributed to all sorts of stuff, not just mathematics. A true renaissance guy. The fact that he solved chess is amazing enough as it is.  
 
10. Alexander Abian for discovering that we must blow up the moon as it a source of all kinds of problems and evil.
 
11. Will Hunting for solving a homework exercise that was supposed to involve advanced Fourier analyis and take all semester but which, as far as I could see (and I only saw it once, so my memory might be failing me) seemed to involve transition matrices, perhaps graphs and the oh-so-difficult cubing of a 4x4 (or maybe a little larger) matrix (related to the transition matrix) and having accomplished cubing a matrix he was then able to solve at first sight a problem that was supposed to have taken a Fields Medallist, specializing in the area, years.
 
« Last Edit: Jul 13th, 2008, 2:49pm by ThudnBlunder » IP Logged

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Re: various physics questions  
« Reply #54 on: Jul 18th, 2008, 9:35am »
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I've been talking to a physics major student about the collapse of the wave function. I told him that the collapse of the wave function is very mysterious to me. He smiled and said that it is mysterious to him too. And, The wave function of any particle...a photon being the easiest to discuss....can occupy a large portion of space. It is only with the collapse of the wave function that the particle is observed at a single point.  We don't really understand quantum mechanics. Neither does anyone else...we just have varying levels of mastery on how to manipulate the equations.
 
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Re: various physics questions  
« Reply #55 on: Jul 22nd, 2008, 8:01pm »
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Here's an old and fun puzzle in physics:
 
An average-size adult has in the neighborhood of 2,000 square inches of skin. Multiplythis by the atmospheric pressure of 14.7 pounds per square inch, giving 30,000 pounds. That's 15 tons!
 
Why don't we feel this enormous pressure?
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Re: various physics questions  
« Reply #56 on: Jul 23rd, 2008, 1:02am »
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on Jul 22nd, 2008, 8:01pm, BenVitale wrote:
Here's an old and fun puzzle in physics:
 
An average-size adult has in the neighborhood of 2,000 square inches of skin. Multiplythis by the atmospheric pressure of 14.7 pounds per square inch, giving 30,000 pounds. That's 15 tons!
 
Why don't we feel this enormous pressure?
Some things you don't notice till they're gone.
We'd hardly notice ten times that, but you'll feel it if there's only a tenth.
 
Besides, we also don't notice this enormous heat; the temperature on earth is about 100 times the average in space. But you can get used to anything, especially if you have 4 billion years of evolutionary history adapting you to the conditions. Not really a question of physics at all.
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Re: various physics questions  
« Reply #57 on: Jul 30th, 2008, 9:01am »
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I recently had a discussion with a physics major student about String Theory, and this is what I gathered:
 
String theory is a theory. Like all theories, it is a model, backed up by mathematics, that attempts to explain some aspect of the universe. String theory is predicated first on the world having a property called supersymmetry. Supersymmetry has never been observed,.
 
if supersymmetry exists, string theory may still be wrong. But if supersymmetry does not exist, string theory is dead.  
 
string theories postulates that particles as we think of them can be replaced with tiny vibrating nodes in spacetime.
 
There are many papers postulating various aspects of the strings if they exist. These papers do not make testable predictions nor is it likely that there will be a testable prediction from these papers in the forseeable future. This failure does not mean string theory is incorrect, but rather that there is no real reason to believe it at this time.  
 
String theory is completely consistent with existing data. Of course, that's by construction. Any theory that says that photons can decay into photons must be false and, of course, string theory makes no such claims.  
 
The one real success of string theory is that it provides a way to envision that all of the forces (gravity, electromagnetism, weak and strong) are all explained by a single mechanism.  It also unifies the quantum world and gravity.
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Re: various physics questions  
« Reply #58 on: Jul 31st, 2008, 11:22am »
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Here are  fun riddles from the Martin Gardner puzzles in the Scientific American Magazine.
 
(1)
Suppose the Earth was in fact a perfect sphere. A steel strip is fitted around the equator, forming a tight band. That band is then cut at one point, and extra foot [30cm] of strip is welded in to the band, and with a deft flick of the band, it briefly is found in the positon where the gap between the band and the Earth is exactly the same sized all the way round the equator. The size of the gap will allow:
 
A. A laser to be shone through the gap and thus demonstrate a spectacular diffraction pattern.
B. A cigarette paper to be slipped snugly through the gap.
C. A mouse to crawl through the gap.
D. A cat to rush through the gap chasing such a mouse.
 
Which answer do you think is most likely representative of the situation.
 
(2)
A group of explorers start at a point P and travel in a perfectly straight line (LEAVING A VISIBLE RED TRAIL) north until they arrive back at P. Then again leaving from P, they travel west in a perfectly straight line (leaving a visible GREEN trail this time) until they arrive back at P. BUT they notice that on the 2nd trip, the green trail does not intersect/meet the red trail. If they were living on a sphere, then the green and red trails should intersect at right angles.
  
Question: Can these explorers be living on the surface of a sphere? If not, what could they be living on?
« Last Edit: Jul 31st, 2008, 11:33am by Benny » IP Logged

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Re: various physics questions  
« Reply #59 on: Jul 31st, 2008, 11:36am »
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I haven't known too many cats which will fit through a 2" gap. Wink
 
For myself, I like this version better, as the answer is even more surprising.
 
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Re: various physics questions  
« Reply #60 on: Jul 31st, 2008, 11:55am »
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Quote:
For myself, I like this version better, as the answer is even more surprising.
 
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Your link doesn't work. I got the message:
 
This topic doesn't exist on this board. 105272235 : 1397.
 
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Re: various physics questions  
« Reply #61 on: Jul 31st, 2008, 12:19pm »
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on Jul 31st, 2008, 11:55am, BenVitale wrote:
Your link doesn't work. I got the message:
 
This topic doesn't exist on this board. 105272235 : 1397.
try here
(he cut off a 9 at the end)
 
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Re: various physics questions  
« Reply #62 on: Aug 1st, 2008, 9:33am »
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on Jul 31st, 2008, 11:22am, BenVitale wrote:
(2)
A group of explorers start at a point P and travel in a perfectly straight line (LEAVING A VISIBLE RED TRAIL) north until they arrive back at P. Then again leaving from P, they travel west in a perfectly straight line (leaving a visible GREEN trail this time) until they arrive back at P. BUT they notice that on the 2nd trip, the green trail does not intersect/meet the red trail. If they were living on a sphere, then the green and red trails should intersect at right angles.
  
Question: Can these explorers be living on the surface of a sphere? If not, what could they be living on?

Assuming no trickery, then they're not on a sphere.
 
The obvious example of a surface they could be on is a torus - there are many other possibilities.
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Re: various physics questions  
« Reply #63 on: Aug 1st, 2008, 10:30am »
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Sure they could be living on a Torus or donut-shaped object.
 
it sounds simple - except for getting a standard North South magnetic field to be set up around the donut.
 
OR
 
They could either be living on a sphere. On a sphere, they will have to have gone South to get back to their starting point [P] - like North along the Greenwich meridian to the North Pole, South along the international date line to the South Pole, then North again back to P.
 
 
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Re: various physics questions  
« Reply #64 on: Aug 1st, 2008, 6:58pm »
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on Aug 1st, 2008, 10:30am, BenVitale wrote:
it sounds simple - except for getting a standard North South magnetic field to be set up around the donut.

It is actually simpler on a torus than on a sphere.  If we think of the torus as the square [0,1] x [0,1] in the plane with opposite edges identified, then we can just take north and west to be the directions of increasing y and decreasing x.  In other words, the torus is parallelizable (the sphere doesn't even have one non-vanishing vector field, let alone a frame).
 
Maybe this wouldn't be a "standard" magnetic field, but then this isn't a standard Earth either.
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Re: various physics questions  
« Reply #65 on: Aug 2nd, 2008, 3:36am »
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Sending an electric current around a loop of wire will give you a suitable magnetic field...
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Re: various physics questions  
« Reply #66 on: Aug 2nd, 2008, 12:58pm »
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Quote:

(1)  
Suppose the Earth was in fact a perfect sphere. A steel strip is fitted around the equator, forming a tight band. That band is then cut at one point, and extra foot [30cm] of strip is welded in to the band, and with a deft flick of the band, it briefly is found in the positon where the gap between the band and the Earth is exactly the same sized all the way round the equator. The size of the gap will allow:  
 
A. A laser to be shone through the gap and thus demonstrate a spectacular diffraction pattern.  
B. A cigarette paper to be slipped snugly through the gap.  
C. A mouse to crawl through the gap.  
D. A cat to rush through the gap chasing such a mouse.  
 
Which answer do you think is most likely representative of the situation.  

 
The gap is 2 inches.
 
If we assume radius r = 4000 miles.  
 
Then C = 2Pi*r and new C2 = 2Pi*r + 1/5280,
 
then new r2 = C2/2Pi = (2Pi*r + 1)/2(Pi) = r + 1/5280/(2Pi),  
 
then the gap is r2 - r = 1/5280/2/Pi miles. or 1/2/Pi feet or 12*2/Pi inches = 6/Pi inches = 1.90985.. inches.  
 
This gap will not allow the cat to rush in or will not be a snug fit to a cigarette paper.
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Re: various physics questions  
« Reply #67 on: Aug 3rd, 2008, 11:17pm »
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Quote:

A group of explorers start at a point P and travel in a perfectly straight line [leaving a visible trail] north until they arrive back at P. Then again leaving from P, they travel west in a perfectly straight line (leaving a visible green trail this time) until they arrive back at P. But they notice that on the 2nd trip, the green trail does not intersect/meet the red trail. If they were living on a sphere, then the green and red trails should intersect at right angles.  
 
Question: Can these explorers be living on the surface of a sphere?  

 
 
The green trail (that starts westwards) must not intersect the red trail (the one that starts northwards) until, of course, both return to the starting point.  
 
On a sphere the two trails WILL intersect before returning to start. therefore I think the explorers cannot be on a sphere. Am I missing something?  
 
 
BTW when you say a perfectly straight line that makes me think that it must be a geodesic-----on the sphere it would be two great circles which depart from the initial point at right angles. So they would meet also at right angles, at the antipodal point.
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Re: various physics questions  
« Reply #68 on: Aug 4th, 2008, 7:53am »
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I see 2 problems:
1. If they go north all the time, they will reach the north pole and stop there.  They will never reach P again.
2. By definition both lines meet at P, so the condition that they don't meet can not be satisfied, whether on a sphere or elsewhere.
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Re: various physics questions  
« Reply #69 on: Aug 4th, 2008, 5:21pm »
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on Aug 4th, 2008, 7:53am, Grimbal wrote:
I see 2 problems:
1. If they go north all the time, they will reach the north pole and stop there.  They will never reach P again.

 
Sorry. I don't get it.
 
Quote:

2. By definition both lines meet at P, so the condition that they don't meet can not be satisfied, whether on a sphere or elsewhere.

 
This is not clear to me.
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Re: various physics questions  
« Reply #70 on: Aug 5th, 2008, 12:42am »
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on Aug 4th, 2008, 5:21pm, BenVitale wrote:
Sorry. I don't get it.
What is north of the north pole?
How can you continue in the northwards direction once you've traveled from P to the north pole? You can't, you're stuck.
 
Quote:
This is not clear to me.
P lies on both lines; so the two lines must meet there, in contradiction of the claim they never meet.
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Re: various physics questions  
« Reply #71 on: Oct 14th, 2008, 3:53pm »
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Would the following qualify as a cranck:
 
http://www.upsite.co.il/uploaded/files/251_0f2d8e2b34a229f1d05ab31eb070b e32.pdf
 
 
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Re: various physics questions  
« Reply #72 on: Oct 15th, 2008, 1:51am »
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on Oct 14th, 2008, 3:53pm, BenVitale wrote:
Would the following qualify as a cranck:
 
http://www.upsite.co.il/uploaded/files/251_0f2d8e2b34a229f1d05ab31eb070b e32.pdf
Well, I see no reason to call him a crank. But I don't find it very remarkable that he discovered a difference between {1,2,3}, {{1,2},3} and {{{1},2},3}. It's hardly a new mathematics.
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Re: various physics questions  
« Reply #73 on: Oct 15th, 2008, 6:35am »
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I also found it telling that after "discovering" that children approach the world in an organic and informal way, the first thing he tries to do is rigidify and formalize his discovery...
 
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Re: various physics questions  
« Reply #74 on: Oct 15th, 2008, 11:13am »
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I thank you for answering to my post.
 
What did you think of his representation of the Unity problem, and the non-locality in nature?
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