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Comment by _underfl0w_ | Hacker News Reader

Part of me likes to thing something crazy would happen if you turned it from the other end. Turn one gear once and the gear at the far other end turns a googol times but melts somewhere around a trillion rotations. Almost doesn't feel too outlandish given a scope that already includes "more energy than the entire known universe has" (per the article) for a measurement.

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I'd like to think there would be a way to turn it, but I'm fairly confident it isn't possible. With that much mechanical advantage, no material will stay together. I'm not sure whether the frame/axles will break first or if it would just strip the gear teeth.

In an imperfect build like this, it would simply bind with any attempt to turn it the other way.

In the hour-long video, from the start to the end, only the first seven gears move visibly, and the 8th moves maybe a pixel. You probably couldn't move anything past the 3rd or 4th gear with your hand, depending on how low-friction the bearings are, how strong you are, and how little you care about hurting your hand. You could attach a long lever to one, but that'll only get you one, maybe two gears further.

Yeah, but that's just an engineering problem.

> that's just an engineering problem

It's not - it's a physics problem - it reaches fundamental physical limits of the universe.

Okay, time for me to go sit in a dark room and think for a bit.

Like he said, an engineering problem.

Pfft, hold my beer.

Your arm is poorly engineered for this particular problem, so you are correct.

All this time we've been fussing about clean energy and perpetual motion machines when all we needed was this machine to apply essentially infinite leverage and generate a universe of energy at the flick of the wrist

Woops accidentally solved fermi's paradox and the mystery of what created the big bang, in one shot.

At first there was God. Then Adam and Eve. Then one of their descendants built this machine and prayed for god to turn the last wheel. Bang! (a big one)

Step 1 is have a universe's worth of energy in your wrist. ;)

You would need a tremendous amount of torque to move the last gear, because gears multiply the angular velocity on one side and multiply the torque on the other. If it took one newton-meter (about the weight of one apple on a lever a meter away from the gear) to move the first gear, it would take a googol newton-meters applied at the other end of the device.

> one newton-meter (about the weight of one apple on a lever a meter away

Aside, but I'm delighted to learn that one Newton is approximately one apple's worth of force. :)

Maybe if you have a very big apple. 1 nM is the force of 1 Newton (1kg on Earth) at 1 meter.

you forgot g, 1kg weighs 9.8 newtons on Earth.

Newton is 0.1 kg on Earth. (Approximately)

It’s actually much worse than that because of reflected inertia. The inertia of the first gear as seen from the last gear is proportional to the square of the gear ratio

Yes, especially if you have a physical system I am curious what happen (eg, do we shear the axel somewhere?)

With each gear reducing your force 100 times, there would be a point when moving the next gear becomes impossible without destroying the machine.

So you either spin the fast gear an impossible number of times, or spin the slow gear with impossible force.

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