Perpetual motion = endless energy?

Now, obviously biology is so far out of my comfort zone that I don’t even know I’m actually talking about sciencephysical rotatorical implied... uh... maths. Or something.

So, anyways, I was talking to a friend (some student of the laws of lightcones or something... buggered if I know what ice cream has to do with anything, though) and I had a brilliant idea.

So, it’s basically: “If we had perpetual motion, surely we’d have perpetual energy.”

“Oh yes,” replied my ice cream gravitational student, “But perpetual motion doesn’t exist.”

And so, my idea, like many of my dreams (like building a death star and stealing Jupiter) was dashed.

But. Suddenly... roughly 10’minutes ago... I had a brainwave...
Isn’t the Earth constantly turning?
If so, couldn’t we harvest that energy?
And with magnets, induction or something, power TV’s or something.

Yeah, I know, I’ll pick up my Nobel prize on the way out.

@shavixmir said
Now, obviously biology is so far out of my comfort zone that I don’t even know I’m actually talking about sciencephysical rotatorical implied... uh... maths. Or something.

So, anyways, I was talking to a friend (some student of the laws of lightcones or something... buggered if I know what ice cream has to do with anything, though) and I had a brilliant idea.

So, it’s ...[text shortened]... or something, power TV’s or something.

Yeah, I know, I’ll pick up my Nobel prize on the way out.

As I was reading this, just before I got to you mentioning our planet, something along your idea struck me too. But where does it take us? 🤔

@shavixmir said
Now, obviously biology is so far out of my comfort zone that I don’t even know I’m actually talking about sciencephysical rotatorical implied... uh... maths. Or something.

So, anyways, I was talking to a friend (some student of the laws of lightcones or something... buggered if I know what ice cream has to do with anything, though) and I had a brilliant idea.

So, it’s ...[text shortened]... or something, power TV’s or something.

Yeah, I know, I’ll pick up my Nobel prize on the way out.

I got some bad news for you shav… Unfortunately your leftist ideals of "you can get something for nothing, and everything is free if it makes you feel good" work just about as well in the universe as they do in in politics...

Yeah, if we were dumb enough we could get energy from the earths rotation right up until the point where we effectively scorched the unlucky half stuck facing the sun while simultaneously freezing the other unlucky half. Got any other brain busters?

@joe-shmo said
I got some bad news for you shav… Unfortunately your leftist ideals of "you can get something for nothing, and everything is free if it makes you feel good" work just about as well in the universe as they do in in politics...

Yeah, if we were dumb enough we could get energy from the earths rotation right up until the point where we effectively scorched the unlucky half st ...[text shortened]... k facing the sun while simultaneously freezing the other unlucky half. Got any other brain busters?

You’re suggesting that harvesting the planet’s rotstional will stop the Earth spinning? Even by induuction?

@shavixmir

The short answer is yes. If we were able to harvest the rotational energy of the earth by "any means conceivable" we would be slowing its rotation down. Its a consequence of conservation of energy ( The First Law of Thermodynamics ). It basically states that if a certain quantity of energy is shared, the sum of all the shared proportions is equal to the original quantity. You cant bake a pie, give me a piece and still (yourself) have the same amount of pie. Actually, its even worse than that as a consequence of The Second Law of Thermodynamics. You can't bake a pie, give me a piece, find out I'm a gun toting right-winger, and decide to get it all back. In the transaction of the sharing (in both directions) some of the pie is always lost to waste. ( crumbs from the cut, stuck to the knife, falling on the floor etc... ). The first law isn't violated, the sum of all the pieces add to the whole but the second law says you will always generate waste pie that is unrecoverable.
In your rotating earth example, if you captured some of the energy from earth rotation, realized it was slowing the earth down and we were all going to die, you will be unable to simply reverse the process and give it right back. Some of the energy will be lost as heat in the transaction.

Secondly, the earth is not in a state of perpetual motion. It is already measurably slowing down.

https://www.wired.com/2009/06/rotational-energy-of-the-earth-as-an-energy-source/

@shavixmir said
Now, obviously biology is so far out of my comfort zone that I don’t even know I’m actually talking about sciencephysical rotatorical implied... uh... maths. Or something.

So, anyways, I was talking to a friend (some student of the laws of lightcones or something... buggered if I know what ice cream has to do with anything, though) and I had a brilliant idea.

So, it’s ...[text shortened]... or something, power TV’s or something.

Yeah, I know, I’ll pick up my Nobel prize on the way out.

There is a possibility of real perpetual motion, or perpetual energy supply, extreme but theoretically possible.

We know the universe is expanding.

Based on that, you make a rope millions of light years long.

I know, it's absurd but for the sake of argument:

You have millions of light years of rope and more millions rolled up and each end on a drum. The universe expands so the two end drums will stretch the rope.

So you harness that energy by having a generator on the drum axis shaft and presto, instant forever energy, at least till the rope finishes unwinding.

That would actually work IF you could first of all GET stuff millions of light years apart AND make a rope say twice as long as the distance between them.

So you can see, suppose the drum is rotating 1 RPM and is the size of a planet and suppose the outer layer of rope is going out at a great velocity.

Lots of energy going on there for sure. So suppose the rope was 1 cm in diameter and there was a million rows and in that drum is therefore a million cm wide and say 10,000,000 meters in diameter. So the number of layers would add up to about one billion. So it's unrolling at 100 million cm per second and you have a million rope wide roll so it takes about 30 million cm per rev and you get one million revs so that is 500,000 cm per second and it took 1 million revs to empty the top layer, 1 million minutes, which is about 16,000 hours or about 2 years per layer and you have 5 million meters times 100 or 500 million times that 2 years or 1 billion years of energy for free, maybe only half considering the inner layers contain less rope than the outer layers so call it 500 million years of energy for free......

I think that rope is extending about 500 km per second or so.

I have been told that the laws of thermodynamics are not real laws at all...

@shavixmir said
I have been told that the laws of thermodynamics are not real laws at all...

I don't know what you mean by that.

To be fair and honest with you, there is an absolutely massive amount of rotational kinetic energy stored in the spinning earth. Lets say we could create a device that captures it at our current rate of energy consumption ( 6x10^20 Joules per year). It would take between 10^8 and 10^9 years before it was all converted to heat and the earth stopped spinning. So it is a massive untapped energy potential, but designing some massive electric motor stator out in space that uses the earth as the rotor is sci fi 3000 unrealistic. Not to mention, whose energy is it?

@shavixmir said
I have been told that the laws of thermodynamics are not real laws at all...

I don't know who told you that, but the laws of Thermodynamics ( specifically the First Law ) may be the most fundamental law of physics that exists and ever will exist.

The law is so fundamental that it doesn't forbid the whole of the universe springing into existence from absolute nothing. In the beginning the void split

0 = -1 + 1

and the universe suddenly exists. All everything is doing is just an arbitrary shuffling of positives and negatives on the right hand side of the equation above to maintain its nothingness, i.e. the Universe believed to be something, in total is ultimately nothing.

Oh well, I guess I’ll have to wait for my next brainwave before I get my Nobel prize.

The rotating Earth isn't a 'perpetual motion machine' and nothing is because there is no such thing.
Nevertheless, since the tides are one of the consequences of the rotation of the Earth relative to the Moon, we can obtain energy from the rotation of the Earth relative to the Moon by exploiting tidal power.
Unlike with the hypothetical perpetual motion machine, none of the laws of thermodynamics aren't violated with that because the Earth's rotation is being (extremely slowly) slowed down as rotational energy is converted to the kinetic energy of the tides. Of course, the Earth's rotation will keep slowing down whether we exploit tidal power or not, so we might as well exploit tidal power as a (MUCH) cleaner alternative to fossil fuel power.
So, you see, extraction useful energy from the rotation of the Earth isn't such a silly crazy idea after all -Its already been done in some small parts of the world and is perfectly practical.

My missedit:

"...none of the laws of thermodynamics aren't violated ..."

should be;

"...none of the laws of thermodynamics are violated ..."

-a double negative makes a positive.

@joe-shmo said
I got some bad news for you shav… Unfortunately your leftist ideals of "you can get something for nothing, and everything is free if it makes you feel good" work just about as well in the universe as they do in in politics...

Yeah, if we were dumb enough we could get energy from the earths rotation right up until the point where we effectively scorched the unlucky half st ...[text shortened]... k facing the sun while simultaneously freezing the other unlucky half. Got any other brain busters?

I did a back of an envelope calculation using some figures from Wikipedia, the Earth's rotational energy is of the order of 9.6E37 Joules. In 2016 world wide power production was 2311 gigawatts. So at that rate of consumption the Earth's rotational energy would run out in about 3 trillion years. There would be no observable effects over mere geological timescales. Sadly I doubt there's a way of doing it.

@DeepThought

I did a calculation after I made the remark as well ( however, I got the units mixed up a bit - it still came out to be absurdly large enough to have no noticeable effect over eons ). And I did "come clean" with the implications a few posts down.

Incidentally, ( I don't know how back of the envelope your calcs were) I think you may have mixed some units up as well.

9.6e37 J/(2.311e12 J/s*3600 s/hr*24 hr/day*365 day/yr) = 1.3e18 yr

Anyhow...
In my opinon, an exercise in CoE, was a more valuable lesson to learn.