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 May 18th, 2018, 05:50 AM #1 Member   Joined: Oct 2017 From: Japan Posts: 48 Thanks: 2 Physics Myth or Reality? Hi everyone, if you would like to take a look here is my take of a still unsettled Physics question, has anyone successfully performed the experiment?
 May 18th, 2018, 06:37 AM #2 Math Team   Joined: Dec 2013 From: Colombia Posts: 7,313 Thanks: 2447 Math Focus: Mainly analysis and algebra Is this what you mean? Thanks from rudimt
 May 18th, 2018, 02:16 PM #3 Senior Member   Joined: Oct 2009 Posts: 406 Thanks: 140 Seriously, drop the letters appearing one by one. It is extremely annoying.
May 18th, 2018, 02:59 PM   #4
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Quote:
 Originally Posted by rudimt Hi everyone, if you would like to take a look here is my take of a still unsettled Physics question ...
Didn't look at your vid and I'm about to go off topic ... but the title Physics, Myth or Reality is a wonderful question of philsophy.

We casually called the laws of physics "The laws of the universe." But that actually can't be true, since the laws of physics are historically contingent. Aristotle, Newton, and Einstein all had theories of gravity. The former two are already falsified, and there's no reason to believe relativity is the last word on the subject; especially since we still don't know, after a century of trying, how to reconcile gravity with electromagnetism and quantum theory.

As Newton famously said, "I frame no hypthotheses." That quote (which I won't discuss in detail today) is Newton's admission that he does not know what gravity is; only how it behaves. Newton understand that science is descriptive and not explanatory. Too many contemporary thinkers fail to appreciate this point.

Quote:
 Originally Posted by Newton I have not as yet been able to discover the reason for these properties of gravity from phenomena, and I do not feign hypotheses. For whatever is not deduced from the phenomena must be called a hypothesis; and hypotheses, whether metaphysical or physical, or based on occult qualities, or mechanical, have no place in experimental philosophy. In this philosophy particular propositions are inferred from the phenomena, and afterwards rendered general by induction.
https://en.wikipedia.org/wiki/Hypotheses_non_fingo

And here's Feynman, right from the first volume of his famous Lectures on Physics.

Quote:
 Originally Posted by Feynman Each piece, or part, of the whole of nature is always merely an approximation to the complete truth, or the complete truth so far as we know it. In fact, everything we know is only some kind of approximation, because we know that we do not know all the laws as yet. Therefore, things must be learned only to be unlearned again or, more likely, to be corrected.
[Italics as in the original]

The Feynman Lectures on Physics Vol. I Ch. 1: Atoms in Motion

So when I see the phrase, "Physics, Myth or Reality," this is what pops into my head. And every time I hear some really smart and trendy scientist saying, the world IS a computer, or the world IS quantum, or the world IS any way at all; I know they are not doing science, but rather metaphysics. And credulous reporters tell a credulous public that scientists say the world IS this or IS that; when in fact science by definition is incapable of making such a statement. No wonder there's a postmodern reaction against rationality. The scientists have oversold their case and written checks they can't cash.

Let's get back to the genius and wisdom and deep understanding of the limitations of science as understood by minds like Newton and Feynman.

Well thanks for reading. It was either this or trying to explain quotients to Zylo, so I went with a little philosophy today instead.

Last edited by Maschke; May 18th, 2018 at 03:09 PM.

 May 18th, 2018, 11:18 PM #5 Member   Joined: Oct 2017 From: Japan Posts: 48 Thanks: 2 That's the effect indeed.
 May 21st, 2018, 05:44 AM #6 Senior Member   Joined: Apr 2014 From: Glasgow Posts: 2,111 Thanks: 706 Math Focus: Physics, mathematical modelling, numerical and computational solutions The Coriolis effect is much, much too weak to affect things like vortices of water in a sink compared to, say the local hydrodynamics. It's a well known con at the equator to get people to bet that the direction of the swirling water will change by stepping past the equator.
 May 23rd, 2018, 05:37 AM #7 Member   Joined: Oct 2017 From: Japan Posts: 48 Thanks: 2 There are different opinions on this topic, the main problem is that the size of the effect is extremely small, yet, if you do a properly design experiment you could detect it in a properly chosen sink. The video shows you how small the effect really is, a tiny fraction of g. Any small perturbation to the system would easily mask the effect.
May 24th, 2018, 01:23 AM   #8
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Quote:
 Originally Posted by rudimt There are different opinions on this topic,
There are always different opinions on a topic. However, if you look at the opinions that matter, (i.e. the literature), the Coriolis effect is well understood and is not an open problem.

Quote:
 the main problem is that the size of the effect is extremely small, yet, if you do a properly design experiment you could detect it in a properly chosen sink. The video shows you how small the effect really is, a tiny fraction of g. Any small perturbation to the system would easily mask the effect.
I'm sure that a sensitive enough experiment could detect it at those scales, but that's besides the point. The Rossby numbers are very large at those scales and therefore a Coriolis correction term is unimportant. Wikipedia gives a good explanation and two good examples:

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Length scales and the Rossby number
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The time, space and velocity scales are important in determining the importance of the Coriolis force. Whether rotation is important in a system can be determined by its Rossby number, which is the ratio of the velocity, U, of a system to the product of the Coriolis parameter, $\displaystyle f=2\omega \sin \varphi$ and the length scale, L, of the motion:

$\displaystyle Ro=\frac{U}{fL}$
The Rossby number is the ratio of inertial to Coriolis forces. A small Rossby number indicates a system is strongly affected by Coriolis forces, and a large Rossby number indicates a system in which inertial forces dominate. For example, in tornadoes, the Rossby number is large, in low-pressure systems it is low, and in oceanic systems it is around 1. As a result, in tornadoes the Coriolis force is negligible, and balance is between pressure and centrifugal forces. In low-pressure systems, centrifugal force is negligible and balance is between Coriolis and pressure forces. In the oceans all three forces are comparable.[26]

An atmospheric system moving at U = 10 m/s (22 mph) occupying a spatial distance of L = 1,000 km (621 mi), has a Rossby number of approximately 0.1.

A baseball pitcher may throw the ball at U = 45 m/s (100 mph) for a distance of L = 18.3 m (60 ft). The Rossby number in this case would be 32,000.

Baseball players don't care about which hemisphere they're playing in. However, an unguided missile obeys exactly the same physics as a baseball, but can travel far enough and be in the air long enough to experience the effect of Coriolis force. Long-range shells in the Northern Hemisphere landed close to, but to the right of, where they were aimed until this was noted. (Those fired in the Southern Hemisphere landed to the left.) In fact, it was this effect that first got the attention of Coriolis himself.

Last edited by Benit13; May 24th, 2018 at 01:31 AM. Reason: errors XD

 May 26th, 2018, 09:28 PM #9 Member   Joined: Oct 2017 From: Japan Posts: 48 Thanks: 2 The effect is well established as far as the equations but is still often misinterpreted. There are still Physics textbooks with a completely misleading explanation, the effect has also been wrongly featured in several tv shows. You are raising interesting points, I will link an article later on.
May 29th, 2018, 01:18 AM   #10
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Quote:
 Originally Posted by rudimt The effect is well established as far as the equations but is still often misinterpreted. There are still Physics textbooks with a completely misleading explanation, the effect has also been wrongly featured in several tv shows.
Unfortunately, this is all too common, not just with physics but with a lot of subjects. I wonder how much stuff on TV is actually true these days.

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