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Galaxies are always Binary Systems? (Astrophysics)
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DPCrisp


In: Bedfordshire
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"Looked at even casually, one can instantly see in the resulting time-lapse image (above) that the two pinballs did NOT fly along identical parabolic arcs (as they should have); unmistakably, the steel ball that was rotating (at ~27,000 rpm) flew higher ... and fell faster ... than the companion ball that was not rotating!"...

...he says the spinning ball "flew higher" but "fell faster". In other words, behaviour totally consistent with reduced drag on the spinning ball (and, you might note, totally inconsistent with reduced weight).

Good catch.

And that chart is a pretty gross misrepresentation. To quote Is Relativity Nonsense? page 6:
These are not two plots of the positions of spinning and non-spinning balls with all else equal. You can see from the bottom left corner that the trajectories are parallel and offset: the two tracks do not originate from the same spot.

Rather than looking at it casually, I printed this out and measured the points. Re-adjusting them to start from the same place, there is still a small difference in trajectory amounting to a 3% difference in angle and either a 1% difference in launch speed or 2% difference in acceleration-due-to-gravity.

However, the curves are not quite symmetrical and the difference in shape-cum-horizontal-speed looks like the difference between air resistance and no air resistance. This is surprising since the subject is the effect on gravity and the vertical difference is less than the horizontal...

As intriguing and fertile as this whole area appears to be, the case is not advanced by wonky data.
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Komorikid


In: Gold Coast, Australia
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Dan wrote:
And that chart is a pretty gross misrepresentation. To quote Is Relativity Nonsense? page 6:


How so? The balls do not start from exactly the same position because in the experiment they are mounted adjacent to one another. Your assumption is that the first dot for each ball is the start position. This is incorrect. The start position for De Palma's experiment has both balls adjacent in the same horizontal plane at the initiation of momentum. The strobe does not capture the start position but all subsequent positions.

The trajectory clearly shows the spinning ball has a different arc.
Sufficiently different to fall outside the standard laws.

However, the curves are not quite symmetrical and the difference in shape-cum-horizontal-speed looks like the difference between air resistance and no air resistance


Both balls are travelling in the same air with the same resistance. The only way one could have no air resistance is for there to be NO AIR (a vacuum)

Both balls have exactly the same aerodynamic profile whether one is rotation or not. This is because of surface boundary lay. The molecules directly touching the surface of the balls are virtually motionless. With or without spin the aerodynamics remains exactly the same for the same shape.
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DPCrisp


In: Bedfordshire
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The start position for De Palma's experiment has both balls adjacent in the same horizontal plane at the initiation of momentum. The strobe does not capture the start position but all subsequent positions.

Sorry KomoriMate, but someone is yanking your chain.

It would have been helpful for the start positions to be aligned "into the page", so that one trace emerged from behind the other... but if you're right that they started next ("across the page") to each other, they should still be parallel, with the first few dots at the same height (and any difference between them growing more pronounced over time). They're not. These are 2 very similar curves displaced both horizontally and vertically.

As I said before, there is a small difference, but it could easily be an aerodynamic one. Parallax even?

This is because of surface boundary layer. The molecules directly touching the surface of the balls are virtually motionless. With or without spin the aerodynamics remains exactly the same for the same shape.

Tell that to the footballer taking a corner kick.
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Chad


In: Ramsbottom
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Komori wrote:
Both balls have exactly the same aerodynamic profile whether one is rotation or not. This is because of surface boundary lay. The molecules directly touching the surface of the balls are virtually motionless. With or without spin the aerodynamics remains exactly the same for the same shape.


So the linear motion, of the ball through the air, causes an interaction between the surface the ball and the surrounding air molecules, but the rotational motion, of the ball through the air, causes no such interaction?... Interesting.
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Brian Ambrose



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Sorry KomoriMate, but someone is yanking your chain


I agree, I think that whole article is a hoax. The guys who did that experiment went to quite a bit of trouble, what with spinning balls and stroboscopic photography, so we're entitled to assume they are quite bright. So it is incredible to me that they could possibly have failed to consider (or mention) an aerodynamic effect when it came to analysing the results, even if in the whole of their closseted lives they have never encountered a single ball-sport. Maybe they should get out more. Either way, I don't think Newton and Einstein are about to be overthrown by these jokers.
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Mick Harper
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In: London
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I can't follow the arguments but this doesn't at all sound like a hoax.
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Brian Ambrose



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Mick Harper wrote:
I can't follow the arguments but this doesn't at all sound like a hoax.


Surely you've seen David Beckham score a goal from a free-kick?
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Ishmael


In: Toronto
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Brian Ambrose wrote:
...so we're entitled to assume they are quite bright. So it is incredible to me that they could possibly have failed to consider (or mention) an aerodynamic effect...


I'm not so sure Brian.

Remember our long-ago, mysterious visitor who had written that book (even!) explaining gravity by suggesting the constant exponential expansion of all matter? You raised some very basic questions and he just ran away.

Is it possible he never considered those questions?

It seemed to me he had managed to avoid considering them, choosing instead to go on enjoying his idea. I guess we are all prone to do that but, typically, the theory-killing questions are little more obscure.

I was amazed that someone so very intelligent could invest so much time in a theory that simply would not work on the most essential levels. Scary really (makes me worry about myself).
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DPCrisp


In: Bedfordshire
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In electricity Ohms Law applies to the inductance of a coil. A given current through a give coil produces a given resistance in Ohms. For DC current 4 Amp at 8 Volts produces 2 Ohms.
For AC current 4 Amps gives 32 Volts which effectively equates to 8 Ohms but Ohms Law can?t have two values for the same current.

Do we therefore say that after nearly 150 years that Ohms Law is wrong?
No we acknowledge that Ohms Law applies ONLY to DC current...

My reference point is Laithwaite's Lecture on Gyroscopes... http://www.youtube.com/watch?v=A89EDdXawvM

Oh, I seeee. It was rather incautious of the Prof to put it that way, since there is always resistance, inductance and capacitance and Ohm's Law always relates to the resistance part and even the self-reactive parts have the form of Ohm's Law.

It was also a bit odd of the Prof to make a thing of M C Escher's intersecting worlds as an analogy for a coil that picks up an induced voltage in one position, but not when turned by 90 degrees. This isn't 2 worlds coexisting but never meeting; it's being parallel or perpendicular to the magnetic field. Inductance, like the gyroscope, kinda demonstrates that the 3 dimensions of space are not independent: sometimes interactions in two dimensions create effects in the third. (Rather the opposite of "dimensions" remaining separate.) Weird shit, sure, but not "mysterious".

An object has something more than a mass. It has a given mass only so long as we push it about in straight lines, weigh it, accelerate it, drop it, etc. But the moment we spin it, it has the property that correspond to the inductance of a coil.

Inductance is enhanced by arranging for the wire to pass through its own magnetic field a lot: by winding it into a coil. What happens to the current is thus dependent on what is... um... already happening to the current. Hence the frequency-dependent behaviour and using Ohm-esque generalisations of current, voltage and impedance. ("AC current" is an average: not even 'the average'.)

Weird electromagnetic behaviour... weird gyroscopic behaviour... weird orbital behaviour... all 'unexpected' behaviour, but only if the interaction of forces and existing motion is not understood. Spinning things gives them angular momentum, but there's nothing new about that; nor does coiling a wire create magnetic fields or inductance.

"At this time, Laithwaite suggested that Newton's laws of motion could not account for the behavior of gyroscopes... Laithwaite later acknowledged that gyroscopes behave fully in accord with Newtonian mechanics"

Newton's Laws applying to a mass are restricted to motion in straight lines and where there is no change in the rate of acceleration, just as there is no rate of change of current in Ohms Law.

For a professor-cum-engineer to say such a thing verged on malpractice. But I guess he took it back.

Spin creates a gyroscopic effect. This is not a new force but the lack of a force that should be there : centrifugal force.

Now I've seen the lecture, I understand this apparently outlandish claim. But all it means is that precession is a circular motion, but arising from the torque at right-angles to the angular momentum, rather than from tension in the connecting rod.
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