Tiny, Floating Dumbbell Rotates 60 Billion Times Per Minute

[Skywizard]

What in the Whirl?

Scientists crafted tiny silica "dumbbells" that are too small to be seen with the naked eye,
spinning them faster than any other human-made object on Earth.

Spinning objects are hypnotic and fascinating, as last year's fidget-spinner craze overwhelmingly demonstrated. But even the fastest fidget spinner trails the new reigning champion of fast-whirling objects: a tiny dumbbell that can rotate 60 billion times per minute.

It's enough to make your head spin.

Spin doctors — er, researchers — recently created the nanoscale rotor and levitated it in a vacuum, blasting it with lasers to set it spinning. Their research, described in a new study, could help reveal how different substances respond under extreme conditions and how friction behaves in a vacuum, Tongcang Li, an assistant professor of physics and astronomy, as well as electrical and computer engineering, at Purdue University.

Over the past decade, researchers have tested the limits — and broken records — for how fast human-made things can spin. In 2008, a motor the size of a matchbook clocked 1 million rotations per minute, Live Science previously reported. Then, in 2010, scientists set a new rotation record when they spun a slice of graphene at a dizzying 60 million spins per minute, Popular Science reported that year.

Three years later, that record was shattered by a microscopic sphere measuring just 4 micrometers — one-tenth the width of a human hair — capable of completing 600 million spins per minute, or about 500,000 times faster than the spin cycle in a washing machine.

For the new study, the scientists tested so-called nanodumbbells made from two joined silica spheres; each dumbbell measured about 0.000012 inches (320 nanometers) long and approximately 0.000007 inches wide (170 nm).

Tightly focused laser light can manipulate tiny objects, and the researchers tested their dumbbells by bombarding them with circularly polarized light, which happens when the electric field produced by the light has a constant magnitude but its direction rotates over time. That polarized laser light forced the nanoscale rotors to spin. In the absence of stray air molecules to slow it down — the test was carried out in a vacuum — the tiny spinner was able to achieve rotation speeds of 60 billion rotations per minute, which vastly exceeds what was previously possible, the scientists reported.

The researchers were also able to vibrate the nanodumbbell in place by blasting it with a laser that was linearly polarized, with its light confined to a single plane, they wrote in the study.

Observations of the objects' rotation and vibration shed light on how vacuums work, the scientists explained. People generally think of vacuums as empty, but physicists see a vacuum as occupied by lively virtual particles, Li said in the statement, and this research with levitating, spinning nanodumbbells brings researchers one step closer to figuring out "what's really going on there" on a quantum level, Li said.


Original article on Live Science





Source: https://www.livescience.com/63139-fa...odumbbell.html



skywizard...

[Did You See Them]

This explains a nagging idea I've had all my life - I'll come back to this sometime.
Thanks

I think spin works out at 576000 mph - anyone want to check

[DeDukshyn]

Posted by Did You See Them (here)
This explains a nagging idea I've had all my life - I'll come back to this sometime.
Thanks

I think spin works out at 576000 mph - anyone want to check

Nope --- it's waaaay higher than that. You have to measure the speed at "X" distance from rotational axis to calculate speed, in this case the total diameter of the "dumbell" is (as indicated above) 170nm - half of that is 85nm for radius, calculate out circumference; I get 534nm around the dumbbell on its rotational axis.

So each rotation on its circumference travels 534nm. At 6000000000 rotations for minute, multiply by 60 for "per hour", to get 360000000000 rotations per hour, multiply that by the 534nm, then take that total and use the google "nm to miles converter" (yup it has one!) and you get 8,052,970,651,395.84960 miles per hour. That's over 8 trillion mp/h!

That's what I got anyway, I think it's right.

EDIT:
... Nope I hugely messed up something somewhere ... or google lied to me, a recalc gets me just shy of 120mph. LOL! So either 8 trillion or 120 or 576,000 ... take your pick

Went over math again ... I think it's ~120mph at it's circumference ... which I guess makes sense considering the distances we are talking here are infinitesimal ...

[Bill Ryan]

Posted by DeDukshyn (here)

Posted by Did You See Them (here)
This explains a nagging idea I've had all my life - I'll come back to this sometime.
Thanks

I think spin works out at 576000 mph - anyone want to check

Nope --- it's waaaay higher than that. You have to measure the speed at "X" distance from rotational axis to calculate speed, in this case the total diameter of the "dumbell" is (as indicated above) 170nm - half of that is 85nm for radius, calculate out circumference; I get 534nm around the dumbbell on its rotational axis.

So each rotation on its circumference travels 534nm. At 6000000000 rotations for minute, multiply by 60 for "per hour", to get 360000000000 rotations per hour, multiply that by the 534nm, then take that total and use the google "nm to miles converter" (yup it has one!) and you get 8,052,970,651,395.84960 miles per hour. That's over 8 trillion mp/h!

That's what I got anyway, I think it's right.

EDIT:
... Nope I hugely messed up something somewhere ... or google lied to me, a recalc gets me just shy of 120mph. LOL! So either 8 trillion or 120 or 576,000 ... take your pick

You multiplied rather than divided.

The dumbbells are 320 nm long, so their radius is 160 nm. The circumference (distance traveled per revolution) is 1005 nm. It does 60 billion of those per minute.

In an hour, the circular distance traveled will be 1005 x 60 billion x 60 = 3,618,000,000,000,000 nm.

That's 2248 miles (per hour).

[DeDukshyn]

Posted by Bill Ryan (here)

Posted by DeDukshyn (here)

Posted by Did You See Them (here)
This explains a nagging idea I've had all my life - I'll come back to this sometime.
Thanks

I think spin works out at 576000 mph - anyone want to check

Nope --- it's waaaay higher than that. You have to measure the speed at "X" distance from rotational axis to calculate speed, in this case the total diameter of the "dumbell" is (as indicated above) 170nm - half of that is 85nm for radius, calculate out circumference; I get 534nm around the dumbbell on its rotational axis.

So each rotation on its circumference travels 534nm. At 6000000000 rotations for minute, multiply by 60 for "per hour", to get 360000000000 rotations per hour, multiply that by the 534nm, then take that total and use the google "nm to miles converter" (yup it has one!) and you get 8,052,970,651,395.84960 miles per hour. That's over 8 trillion mp/h!

That's what I got anyway, I think it's right.

EDIT:
... Nope I hugely messed up something somewhere ... or google lied to me, a recalc gets me just shy of 120mph. LOL! So either 8 trillion or 120 or 576,000 ... take your pick

You multiplied rather than divided.

The dumbbells are 320 nm long, so their radius is 160 nm. The circumference (distance traveled per revolution) is 1005 nm. It does 60 billion of those per minute.

In an hour, the circular distance traveled will be 1005 x 60 billion x 60 = 3,618,000,000,000,000 nm.

That's 2248 miles (per hour).

Look at the diagram, the direction of spin is around the width, not length ... radius is 85nm.

I'll let you calculate that out again, because I obviously failed miserably at that part! lol!

[scanner]

Pretty slow, when you compare it to E=mc2 670,616,629 mph speed of light

[Did You See Them]

Posted by scanner (here)
Pretty slow, when you compare it to E=mc2 670,616,629 mph speed of light

That's what I want to work out ! - what the radius would need to be if it were rotating at 1 billion times a second, to exceed the speed of light.

[Bill Ryan]

Posted by Did You See Them (here)

Posted by scanner (here)
Pretty slow, when you compare it to E=mc2 670,616,629 mph speed of light

That's what I want to work out ! - what the radius would need to be if it were rotating at 1 billion times a second, to exceed the speed of light.

It's a fun question. As best I know, according to Special Relativity, that could never happen in practice because the mass of the END of the rotating dumbbell (or the end of anything that was rotating) would increase towards infinity — in theory — as the speed of light was approached. *

But yes, the speed it goes is 'pretty slow'... only because it's so tiny. The distance traveled at the circumference is proportional to the square of the radius, so one can estimate what the radius would need to be to get to near light speed.

If, for example, it was going at (say) 2,248 mph as it may be right now, to reach 670,616,629 mph (the speed of light), that's a multiple of 298,317. The square root of that is 546.

So to reach relativistic speeds, the radius would have to be 546 times as big... which (if the existing radius was 160 nm, and maybe I misunderstood that) is still pretty small, at about 0.09 millimeters: in other words, maybe something like the size of the period at the end of this sentence. And of course, that's if it was still spinning (or trying to!) at 60 billion rotations per minute.

~~~

* A footnote on the mass increase thing (for anyone who cares!). This is interesting, because the tangential velocity of any point on a rotating arm increases differentially towards the end of the arm, where it's moving at its fastest through space. But in a rapidly rotating object, other points are moving pretty fast, as well, if not quite so fast as the very end point.

By Special Relativity, as it rotates faster and faster, as best I understand this means that the mass of the arm would increase differentially, as well. In other words, the mass of all the points on the arm would increase steadily according to the square of their distance from the pivot point.

So it'd be a much more complex calculation (calculus would be needed) to figure out the increasing moment of inertia of the entire spinning object as the speed of light was approached at the end of the rotating arm. No way am I even going to try to do that here.

Other input from physicists and mathematicians on the forum is most welcome. (And we do have some!)

[Did You See Them]

As a child of about 5 or 6 ( and don't ask how this idea came to me at that age ! ) I used to imagine what would happen if in space you sat on top of a stationary record player and extended out a straw and then kept attaching more straws - getting longer and longer etc !

At 33 rmp ( the speed of old records ) the straw would have to be thousands upon thousands of miles long, but without gravity to weigh it down or to exert force as it swung I wondered if it could achieve and then surpass the sped of light ?

Years later when seeing Nasa's "Teather" experiments I wondered if this was something that they might actually try to attempt.

[Alanantic]

I got a feeling everything in this reality has limits. I think it's the Plank constants of space/time, the universe's 'resolution'.

[Agape]

Advance quantum entanglement option between the two bells rotating in vacuum and you may be close to designing your own ‘perpetum mobile’ or even free zone energy source but to agree with Bill,
nothing lasts forever in our relativistic Universe.