Not me!😂

I was thinking about this, and was wondering if gravitational wave detectors count as the biggest lasers we have ever built.

@@CupCakeArmy1 RE: "I was thinking about this, and was wondering if gravitational wave detectors count as the biggest lasers we have ever built." The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool. Two large observatories were built in the United States with the aim of detecting gravitational waves by laser interferometry. These can detect a change in the 4 km mirror spacing of less than a ten-thousandth the charge diameter of a proton. These lasers were built for sensitivity not power. The most powerful laser beam ever created has been recently fired at Osaka University in Japan, where the Laser for Fast Ignition Experiments (LFEX) has been boosted to produce a beam with a peak power of 2,000 trillion watts - two petawatts - for an incredibly short duration, approximately a trillionth of a second or one picosecond. References: en.wikipedia.org/wiki/LIGO www.ligo.caltech.edu/page/what-is-ligo theconversation.com/worlds-most-powerful-laser-is-2-000-trillion-watts-but-whats-it-for-45891#:~:text=The%20most%20powerful%20laser%20beam,trillionth%20of%20a%20second%20or www.sciencemag.org/news/2018/01/physicists-are-planning-build-lasers-so-powerful-they-could-rip-apart-empty-space

Material for the lanyard /elevator cable needs resistance to burning up in the atmosphere for every minute, second, days and years.

Satellite laser tracking engineers are living the dream

Earth's way of saying goodbye 👋

"unlimited power" in evil voice

That's not a problem, it's a solution! Use that current to power the climber!

Best

well for a space elevator, you need a station at 35.786 km height. So you would need to travel 35.700 km. to put that in relation, the ISS is only 400-440km high. That's a pretty long elevator.

The use of decimals threw me off for a moment.

Use a truss 50 feet wide or so.

well if we did manage to build a cable made of steel (obviously not)...aliens would have no problem locating our position and coming over to say hi. Alien: "Oh we just saw this huge arrow pointing to earth".

Clang says otherwise

“I’m not a space engineer, but I’ve played one in a game”

“I’m not a space engineer, but I’ve played one in a game”

He didn't breakdown the math lol. Vector calculus is not fun

what about starving to death?

just carry the food for a 1 year climb, what's the big deal?

@ Carrying the 35 tonnes worth of calorie dense food on your back for your life long journey.

@AlexNOSAM thicc ladder

@@OhSeeBarber you are THICC

Hey, yeah! We should just build a set of spiraling stairs up to the Clarke belt! Just make sure everyone holds onto the handrails and wears a spacesuit... :)

How does this seems so stupid but extremely smart at the same time

Don't skip leg day

@@maxbuskirk5302 Just don't look down. Imagine if you trip and you just keep falling through the staircase all the way down, hitting all thousands of stairs.

@@edin101 True, I thought this comment was idiotic but also sounds smart at the same time.

Meaning: when you get 1,000 miles away from the station it'll surrender.

Now it has been 6 years ... did you finally do something?

@@AkaRyrye83 my ex girlfriend lol and I got promoted

+jamdram ;)

+jamdram How... Uncivilized

+Practical Engineering Thought you were a mechanical engineer looking at your other videos!

Mechanical is where it's at. We'll let him indulge in his delusions though ;)

Road networks, powerplants and sewage systems are nothing to laugh at. You owe most of your modern comforts to civil engineers.

Excellent plan, but you'd probably want either a nuclear reactor or hydrogen batteries up there as well. So your elevator doesn't stop/fall out of the sky at night.

I sort of like this idea, but the Solar implementation at the top looses me, as well as the break point for the laser. Starting with the laser break point(meaning the point where the elevator switches from Earth to the "space laser"). That specific point, would have to be almost outside the atmosphere to be really just economic enough to implement. Reason being, we would want the "space laser" to(as you also say) avoid distortion to get us up there the rest of the way, but also the break(or switch over) point would mean that there would have to be some power compensation(because of the "Earth laser's" distortion) before we reached the breaking point. That would also mean added weight to the lift, because(with current technology) circuitry involved to make a regulator which could handle the power load for that lift, would only add more weight causing yet again a power vs weight challenge. The idea of putting a solar array at the top, again involves the idea of both electrical power vs weight. A decent enough solar array capable of producing that kind of power to push a laser that pushes a cart up a cable, in addition to the to the distortion of the "space laser"(yes it still has some distortion in space, just not nearly as much as it would going through the atmosphere), would mean that you would need a LOT of panels to create that decent load. A lot of solar panels means a lot of flat usable space, which can be very hard to achieve especially when the counterweight needs to be certain mass which might not mean enough space for panels, in a realistic format.

And who says that it can only be one energy source. Why not eletrcal power from a wire to start and then a boost from a reusable rocket finished off with the Lazer from the top powered by a solar array. Then on the return Lazer to gravity.

In addition to the other answers, I would like to point out the havoc such a laser would cause on earth, were it to ever miss the panel (and part of the beam WILL miss, laser beams are not perfecty homogeneous tubes of light even in vacuum)

The problem is that you don't need power at the top: you get free acceleration from centripetal force.

Better not mention that a similar calculation done by someone (not me) who is familiar with the mechanics of elevators puts the diameter at the top as something like 2Km for a steel cable. That's the thing with physics - no matter how much you know or how good you are at the math its still horribly easy to get something wrong. The tiniest misstep like forgetting to factor in reducing gravity with height tends to make all the difference. The gravity at the orbital geo-lock point is of course zero by definition.. :)

I'd love to see him respond to this.

"lightfortnight" #respect

@@Lucien86 Bzzzzt!!! Nope, it's just balanced by centrifugal force.

My previous post says the top of the cable, its widest point is not there but somewhere at a midpoint. The reason that a steel cable ends up at anything like 2 Km wide in the middle is that 50,000 Km is very very very long for a steel cable.

Above the atmosphere is fine with me.

Are you advocating for a thing dragging a cable through all the circumference of Earth, at surface level with all its irregularities, mountains and seas, natural reserves, cities and what-not (yes, there are several cities located right at the Equator too). I think the UN Security Council would not approve...

My story about the Space Elevator was published under my previous married name in 2005. I was thrilled. Arthur C. Clarke and Ray Bradbury were sponsors and the main impetus behind the contest was Bradley Edwards. I lost my only copy of "Running the Line: Stories of the Space Elevator." (Divorce and ex sold my books 😭 as he is a very mean thing). I caught him, but only got a little of my books. Anyway, I was inspired by the idea of a Space Elevator.

Except you died before you could get to breathable atmosphere.

Megan Pham I appreciate this video too-you can tell he knows what he’s talking about because he doesn’t hide behind a lot of technical jargon. Also: he uses the terms “centripetal” & “centrifugal” correctly and explains the consequences of those forces correctly, which is a level of detail I don’t often see in videos about space elevators

+Luka P Thanks, this is really kind. I am doing my best to strike a balance between good technical content and general tedium. My goal for the channel is to increase exposure to the field of engineering and make it more approachable, so that comes with some simplification of the content. Hopefully not too much though!

it may even be like a thermo couple with diff chartges tempatatures build up voltages along the line.

Thanks Keith! That's always nice to hear!

+Amar Gandhi If anything, a german accent would go better with a video like this. Maybe he can fake one next video!

CheeseWithMold No...a good Russian accent...."we build for mother Russia commrade".

yeah ;) way to put yourself down...from one pale whiteboi to another

Let's get realistic - a Chinese accent would, at least, be believable.

They can be built tomorrow, but channels like these don't like practical solution for futurism problems. For something more down-to-earth, go to Isaac Arthur's channel and watch the videos about spaced towers and power satellites. (And yes, I do realize most of his video are about interplanetary and space stuff, when I said he's down to earth. Bad pun intended.)

Or Catapult?

@@Broockle massive cannon is not actually the worst idea

@@NathanK97 It is the moment you experience neckbreaking G forces when the canon fires due to acceleration

TO: Alvaro S. There's also Arthur C. Clarke's novel 3001: The Final Odyssey, which goes into great detail about a space elevator. He describes an Earth which has four space elevators that connect to an inhabited ring around the planet. The towers containing the cables are inhabited as well.

@@spaceman081447 I have that novel, too. You can call me a fan of Clarke's 🙂

I think the problem is the loss of energy because of the lenght of the cable, the material's resistance i think it is

carbon nanotube is basically a superconductor. we could use the tethers travel through the atmosphere (friction) to generate electrical current. the climber could theoretically just draw power straight from the cable as it climbs, provided the structure used to grip the tether is conductive as well.

What are the carbon nanotube properties, couln't we build all from nanotubes ? I speculate it will be the most expensive material.

In order to have an electric circuit, you need two conductors, and thus two cables. And since they'd be whipping around in the atmosphere, they'd short out whenever they touched each other.

Hungry Guy not entirely true. you have one circuit, negative/ground at the base, positive end at the orbiting mass. the cable itself just allows flow, then the climber as two sets of grippers, negative and positive, basically just making a mobile flow gate with attached motor/control center.

this entire video is nothing but a theory lol

Ironically on "practical engineering" smh

Whatever they do, "practical engineering" would do his most theoretical work, and Isaac Arthur would do his most practical. :P

Pretty sure that is what he is referring to when he talks about extension cords (ie well due to resistance and such you wont have enough power left long before you reach even a quarter of the way)

@@GummieI Why not have a generator on the elevator? Not sure how feasible that is with how much fuel you would need but that is what immediately came to my mind

@Robert Ibey I am by no means an expert on this topic but generators are HEAVY, VERY HEAVY, I don't think most generators output enough power to lift themselves in the first place. Beside that generators still do need some kind of fuel to generate power in the first place, so what would said generator use as fuel? Wind? Well there are no wind when the elevator is in the space part of it, or maybe its just a day without any wind. Solar panels, what about on the earth part of the elevator journey and a cloudy day?

Gummiel u right

@@GummieI We can build fuel-based generators that can lift themselves off the ground WITHOUT needing a cable to climb, so this should definitely be doable.

That's what I was thinking, imagine fusion ;) probably do the trick

Because if shit does hit the fan you will send the radioactive cloud around the entire planet with the help of high altitude winds. Subs have the added bonus of being surrounded by water, a very effective radiation shield

+Bonta kun hmmmm fair point, obvs not with fusion but that's a long shot anyway isn't it ;) I still think it would be an option, it would be the best looked after reactor on the planet and short of the whole thing falling down I can't see why shit would hit the fan especially with the modern quality of reactors

+Bonta kun and maybe the craft could have a very lightweight payload? One that could be easily ejected if a problem occured? I mean although a lot of energy would be needed it wouldn't need to be like a full city reactor would it? I don't know how much the thing would weight

By the time we have effective fusion we would probably have found methods to mass produce Graphene and make cables out this ultra strong superconducting material, then the power source can be on the ground since power reactors usually are not built to be lightweight

Too long for regular wiring. It's the same reason power plants are spread out instead of all being in one place, cause you lose energy over longer distances. You could assume that room-temperature superconductors have been figured out as well as nanotubes, but even in that case, if each metre was only 10 grams, that's still thousands of tons, and then that old taper gets you again.

Is that true in a vacuum though? I thought the reason you lost power over distance was the wind stealing ions?

@@kahlzun It's resistance.

It needs to be a super conductor to not lose a lot of power from resistance. Or a lot of small energy sources along the cable, which would increase the weight.

Or a Nuclear Reactor ...

How about we attach a rocket to a flying machine that will get into orbi-... wait a minute...

Kinda defeats the purpose my guy

Yeah but you lose the risk of dying if your rockets fail

What's the point then using the elevator when all are you using is rockets

That's still gonna be one tall as fucking power grid. Also you still need God beam for enough laser to pass through all that atmosphere high up.

We need Tony starks arc reactor tbh

+Berrymouse only one way to find out!

Fight?

Depends on where it snaps.

Watch Gundam 00.

that was my first thought as well.

I thought you meant between the earth and the moon😂😂

Exactly, its "easy" to get in orbit from the Moon's surface. The problem is here on Earth.

what practical purpose could a lunar moon elevator serve? The experience of building it would hardly justify the absurd expense, especially considering it would do little to simplify the construction of one on earth since the fundamental material demands would be so different. All the equipment and materials would first have to be flown to the moon, an enomous and unprecedented endeavor of itself

+charlesissleepy It would make sustaining a lunar base way cheaper over the long run, especially if you consider wanting to bring lunar material back to Earth in mass. I think you also underestimate how beneficial having a stepping stone to an Earth space elevator would be. Even if none of the developed technology crossed over (which is a bit of a ludicrous proposition), just from a fiscal standpoint of fundraising (particularly in the current socioeconomic climate), it is a far more likely path to actually get off the drawing boards than building an Earth space elevator first. Building a lunar space elevator offers far less risk, while still offering substantial reward if successful. And it is far more likely that whatever technologies, processes, and manufacturing techniques that were developed for a lunar space elevator, would almost certainly directly lead into what would be used for an Earth space elevator.

A lunar space elevator presents a very distinct set of engineering challenges.The moon has inadequate rotation to permit the construction of a space elevator of the same working principle as an earthling one and would have to use lagrange points instead. This means the tether would have to be considerably longer than on earth, 56,000 km on the earthfacing side. The lower mass and lack of atmosphere permit the use of a uniform diameter tether made of existing engineering materials, which clearly already sets it apart from on earth based design (and no research into CNT in massive scale). The tether itself would be massive (using the length and proposed cross section area of the ribbon i figure around 66 metric tons, very likely i bungled the math though) and very expensive both to produce and to convey into lunar orbit. All without much economic motivation, save perhaps He-3. Long-short I don't see it preceding an earth-based project, since any practical use it might have almost presupposes one on earth.

Since the Moon is tidally locked with one face permanently facing Earth, the only place where one would work would be on the far side of the Moon where any kind of centrifugal force would be found. Taking that into account, it wouldn't make much sense taking material to the Moon, landing it from orbit and then lifting the same material out of the Moon's gravity well up to a point where we could reach by simply extending the lunar orbital eccentricity to the point of meeting the same point in space where the counterweight would be. If you are looking for an economical, efficent and faster means of getting to any of the Lagrange points, it would make more sense to use the Moon for a slight slingshot boost to get you there. Now if you are looking for a means to move stuff to the lunar surface, then you may have a point. But for the counterweight to overcome the gravitational pull on it and the mass of the tether, the counterweight would have to be much much closer to Earth for Earth's gravitational force to pull on it with sufficient force to overcome all that lunar weight. I'm not sure what the math would work out to for all of this, but I could see it being done. One of the advantages of having the Earth's space lift's counterweight being beyond the Clarke Belt is that spacecraft launched from the counterweight would be able to put all that centrifugal force to use by merely undocking and being slung into space! It would be interesting to see if and how all that would work, essentially using minimal energy to move materials to the Lunar surface by this means.

Since the Moon is tidally locked with one face permanently facing Earth, the only place where one would work would be on the far side of the Moon where any kind of centrifugal force would be found. Taking that into account, it wouldn't make much sense taking material to the Moon, landing it from orbit and then lifting the same material out of the Moon's gravity well up to a point where we could reach by simply extending the lunar orbital eccentricity to the point of meeting the same point in space where the counterweight would be. If you are looking for an economical, efficent and faster means of getting to any of the Lagrange points, it would make more sense to use the Moon for a slight slingshot boost to get you there. Now if you are looking for a means to move stuff to the lunar surface, then you may have a point. But for the counterweight to overcome the gravitational pull on it and the mass of the tether, the counterweight would have to be much much closer to Earth for Earth's gravitational force to pull on it with sufficient force to overcome all that lunar weight. I'm not sure what the math would work out to for all of this, but I could see it being done. One of the advantages of having the Earth's space lift's counterweight being beyond the Clarke Belt is that spacecraft launched from the counterweight would be able to put all that centrifugal force to use by merely undocking and being slung into space! It would be interesting to see if and how all that would work, essentially using minimal energy to move materials to the Lunar surface by this means.

quick research, Martian Clark belt is at 17,000 km, so much closer. Olympus Monds would not help with the gravity as it's influence would be minuscule, but it would help with the laser powering as it's peak is above martian atmosphere. And the pull on the tether from the mars would be significantly lower as the gravity is only 1/3. I can not calculate the tension stress chart that you drew .. would kevlar be strong enough?

The only problem with that idea is that I can't see how building one there would help get material off of earth!

It would not help, but Mars could become a space hub of a solar system. One can use space elevator to catapult space ships into space for free (literally like a sling shot). So it is not about earth, it is about humanity as a space ferrying species.

I'd say that it'd cater to the Martian segment of the market, how many people live in Mars? Oh, wait, you mean that place that is like Antarctica and the Sahara combined plus no air and lots of radiation. You'd get more customers for Rolls Royces in Haiti's shanty towns, really.

+Albion Laster That's the attitude!

+Albion Laster lol

+Practical Engineering Hey, just a nitpick, but at 2:18 you say "force of gravity", but show the equation for acceleration due to gravity, the term gotten when canceling out the little m's. Not a big mistake, just wanted to make sure you knew it was there!

+Matteo Mcdonnell Yeah I played a bit loose with terminology since the mass term cancels out in both equations. I take a bit of liberty with the rigor because I know no one's relying on me as a primary source for engineering education.

Of course! I really value what you are doing, man. I love every bit of your videos.

Resistance grows with distance. So no.

@@3gunslingers Sure, but there could be small stations on the tether to help pass the electricity along.

@@Hallowed_Ground How does that work? And why not put a small nuclear power station directly on the cabin? arxiv.org/ftp/arxiv/papers/1802/1802.07443.pdf

@@3gunslingers this. i scrolled so long to see someone suggest nuclear cabin. we have it in US Subs already. A micro reactor would provide all the power needed.

The problem with that would be that the electricity would just flow PAST the climber, as the tether needs to go past it uninterrupted. Also with a single cable you wouldn't have a closed loop for the current. So you'd need to use two cables that need to be insulated from each other. Either you'd get power from current that you let pass from one cable to the other, or one of the cables is a guiding cable and the other one is a pulling cable that you just reel in from the top. Which would mean that you'd need to accelerate 1000 cubic meters of carbon nanofibers per square centimeter of cable cross section at the climber. Or you could just send the current past the climber and transfer power by induction. You'd still need two cables in close proximity to in order to shield any stray fields , because else you'd have the biggest wireless power transmission antenna ever conceived. @Keyboard runner Having a nuclear reactor next to a structure that could wipe out a whole county if it would break due to ratiation damage does not sound smart. But a space elevator is such a crazy concept that that might actually be the smartest solution... After all, you only need radiation shielding on the side with the cable and passengers.

XD

*Throws projecc in the trash*

the best balloons only get to about 37km and space is said to start at 100km and with any worthwhile payload you wont get nearly to 37km due to weight and any lower and you get a lot of atmospheric drag which will make any vehicle meant to grab the payload a lot more expensive fuel wise. Anything worth taking up would at least be taken up to more then 300km like the ISS, not to mention satellites orbit at like 35,000km, so boasting a payload to such heights would require a lot of fuel too. If they could design a space craft that could gain more fuel then it loses by refueling in such a way then their may still be hope for such an idea but it would take a lot of engineering to design such a craft that could overcome such obstacles.

The real problem is that even lifting up to the limits of the atmosphere doesn't actually help you that much - you then need to accelerate sideways by somewhere between 7 and 11 km/sec (can't remember the numbers offhand) to get into orbit. That satellite swooping down would hit the payload like a head-on collision between two of our fastest hypersonic planes at full speed, even if you could adjust its orbit like that.

8 km/s according to 'What If?' by Randall Munroe. In it he says that using a rocket to go lift a payload 100 km vertically is the easy part. it's getting to 8km/s horizontally in order to orbit that takes most of the the fuel.

+Brad Evans .. that is the hard part.

The ballon part is unlikely, because drag. The grab part is theoretically possible and is actually a partial space elevator. Look up "Skyhook ". Mind you, the momentum still has to come from somewhere.

Whats the point then? You need to power the elevator not the counterweight

industrial?!

No, everyone knows that EE's work with magic and that we just have to take your word for it. Trust me, we're on to you guys.

define ''best''

Whoops!

+Practical Engineering but your good at math so that's good :) Awesome video's and yes Civil engineering = awesome!

Mechanical engineering > Civil engineering

Then you need two tethers for the circuit?

Well, first solve the problem of the cable and then think about the energy issue, which seems complicated enough but maybe less absolutely impossible.

?

?

Oddly enough that would be useful for observation purposes or it may make a gravitational slingshot a lot more controllable by making the distance from the planet rather precise so you might be able to calculate the exact power of the maneuver

+KerbalEssences I agree

Do we assume that the space elevator has to touch the ground? If we have a massive object orbiting at a distince comparable to the ISS lowered a cable into the upper atmosphere, you would not need carbon nanotubes for it to hold itself up. Suspend a platform from there and create your elevator. Then you can use conventional airplanes to take passengers up to the platform. BOOM - 2 stange space elevator! Though it probably would need to be a bit higher than the ISS, so it does not burn up with air friction at that speed, but it would certainly not need to be 22,000 miles away. I am pretty sure that there is a distance that would work with conventional materials.

+tomthy Crystal _"If we have a massive object orbiting at a [distance] comparable to the ISS lowered a cable into the upper atmosphere"_ The reason to build a space elevator is to make getting into space easier. And the hardest part of getting into space is the first 100 km, mostly because of the atmosphere. The Saturn V rocket that sent people to the moon and back used 96% of the total mission fuel to get the capsule and lander into low earth orbit; going to the moon and back. In terms of delta-V; going from the surface to the ISS is about equally difficult as going from the ISS to the moon and back.

This is all true but you're exaggerating a little. 96% of the fuel used to get in low earth orbit sounds a lot, but that's because it's carrying all the fuel that will be used to get to the moon form there and back. Yes you need a lot of energy and the amount of energy needed to get to the moon and back isn't that much but but if you just want to arrive at low earth orbit the amount of energy needed still goes down exponentially.

_"96% of the fuel used to get in low earth orbit sounds a lot, but that's because it's carrying all the fuel that will be used to get to the moon form there and back."_ You're right, but I think you're missing my point. If you want to go from Earth to the Moon by rocket you need to take all of that fuel. A space elevator would save the fuel required to take the spaceship from surface to space AND the fuel needed to bring the fuel for the trip to the moon. Taking the Apollo mission as an example that's 96% of the total fuel cost of the mission. But even in absolute delta V; surface to LEO is about 9.5 km/s, vs about 8 km/s to get from LEO to landing on the moon and back. In other words, the first 250 km requires more energy than the last 770,000 km.

Carbon nanotubes have been produced, just not in bulk. They aren't room temperature superconductors.

*_what about when they are cold_*

sure not room temperature. but what about space temperature

They would be very hot heated by the sun.

@@IamGrimalkin Who needs room temperature superconductors? They just need to beat 36,000km of inevitably imperfectly focused laser. @Muh Face The temperature would vary depending on whether they're in the shadow of the Earth or directly exposed to sunlight, and even then not necessarily very hot depending on the specific properties that nanotubes in macroscopic structures wind up having (e.g. if able to be constructed with highly reflective surfaces they could stay cool even in direct sunlight).