Can We Create Artificial Gravity?

One of our biggest problems we face when travelling
in space, is the atrophy our bodies endure while in microgravity. The astronauts on the
international space station have to exercise several times a day to maintain their bone
and muscle strength. But is there an alternative? Can we create Artificial Gravity?
I’m sure you have seen the idea before in movies like 2001: A Space Odyssey where the
entire space station spins to create an artificial gravity. The people inside can now walk comfortably
just like just on earth. It does this by exploiting centrifugal force.
Now it seems that whenever someone mentions centrifugal force, angry mobs will show up
in the comment section. Declaring it isn’t real. Which just isn’t the case. Let’s
see why NASA developed this huge centrifuge to test
the possibility of simulated gravity back in the 1960s. Here we are looking from inertial
frame of reference, that just means we are looking from outside perspective and we can
clearly see that there is no force pulling this guy outwards. It is just his inertia
carrying him forward, and the floor he is walking on provides the centripetal force
to prevent him from flying off. But what happens if our reference frame moves
with the astronaut. This is called a rotating reference frame, or a non-inertial reference
frame. To him, the rest of the world is moving, and he is standing stationary. In this reference
frame centrifugal force is absolutely a real and measurable force, pushing him downwards
just like gravity. The only thing that is fictitious is his perception of what is causing
it. This occurs because in physics and engineering,
we must balance forces. The system has to be in equilibrium. Newton’s third law states
for every action there is an equal and opposite reaction.
So if centripetal force exists in this reference frame there has to be a force pushing him
outwards. That is centrifugal force. And the moment the rotation stops it vanishes again.
So if this works so well, why haven’t we seen a spinning space station yet? Well one
problem is size. To make this practical we need a massive ship, which would be incredibly
expensive to get into orbit. The acceleration your body will experience
is directly proportional to speed and radius of the space station. We can calculate the
gravity Space Station V from 2001: A Space Odyssey would generate with some pretty simple
math. The space station V had a diameter of 300 meters and spun on it’s axis once every
60 seconds. That would put its gravity at about the same
as the moons. For it to have a gravity similar to earths it would need to spin once every
24 seconds. If were to make this a realistic size, let’s
say the same size as the international space station. It would need to spin once every
10 seconds. This would probably be pretty disorientating, just ask Sandra bullock.
Another problem we face on smaller stations like this, is the gradient in acceleration
you would experience. Because the acceleration is directly proportional to the distance to
the rotational center, your head will experience less artificial gravity than your feet. This
would force the blood to your feet, just like when you spin a bucket of water around. This
effect will diminish with a larger stations. So to make a practical space station with
artificial gravity the station would have to be huge, which is simply too expensive.
Besides, the ISS is most valuable to us as a laboratory to test the effects of microgravity.
But what if money was not an issue. What would it take to get a space ship like Elysium,
built for the mega rich as an escape from turmoil on earth, into orbit?
Elysium dwarves Space Station V measuring in at 60 kilometers wide and it is estimated
to weigh about a million metric tons. Space x can currently launch a kilogram into space
for about 2720 dollars, with their falcon 9 rocket. This will be reduced to about 1650
dollars per kilo when they launch their falcon heavy variant at the end of the year. But
it would take over 18 thousand launches to bring the one million metric tonnes to low
earth orbit, that’s 1.65 trillion dollars to just get the materials of Elysium into
space with current technologies. Then we have to worry about the costs of materials and
engineering that would go into building something of this magnitude.
That is far more difficult to calculate, but we can take some clues from the ISS. It is
estimated to have cost about 150 billion in total. It took 36 shuttle flights at a cost
of 1.4 billion each to bring the materials to space. That’s a total of 50.4 billion
dollars. So the launch costs were just 33% of the total cost. A conservative estimate
for the costs of Elysium could be put at 5 trillion dollars. That’s 62.3 Bill Gates,
but there are half a million people on board Elysium, so if the cost was split between
everyone that would be about 10 million each. That isn’t so far-fetched and the price
of space travel is destined to reduce in the future.
We do have materials strong enough to build a structure like this. The forces on Elysium
would be similar to the ISS, other than the additional stress created by centripetal and
centrifugal force. It’s interesting to note that the designers of Elysium took note of
this. The stress in a spinning structure like this would decrease as you move away from
the rotational center. This means it would need a stronger structure the closer you get
to the center. This clearly influenced their design with these tapering spokes. But we
run into some problems when we realize there isn’t enough aluminum in the world to build
this thing. It would take at least 10 years’ worth of the world’s total aluminum production
just to build the structure. This would cause a huge surge in the cost of the material.
An alternative method could be sourcing the materials from space. This could reduce the
launch costs and there is plenty of metallic material available on the moon and on near
earth asteroids. So this technology is definitely possible,
our only barriers are launch costs and material availability. Something on the scale of Space
Station V would be easily achievable, who knows maybe we’ll be travelling to space
as tourists in the near future. Once again thanks for watching, I have a little
bonus for you at the end of this outro, you can skip ahead or wait to watch it. I’d
like to thank my Patreon supporters Bastien, Nick and FG for helping me revise this video.
Your support is really appreciated. Thank you. If you would like to see more content
or support Real Engineering. The links for my Patreon, Instagram, Facebook and Twitter
accounts are below. So I promised to include this in my last video,
but I couldn’t figure out how to include it in this video in a seamless way. The centrifugal
governor was used in the industrial revolution to control the amount of steam entering the
steam piston. Which was essential as the supply and demand can vary with fuel and load.
For example if the engineer puts more coal into the boiler, the pressure will rise and
these masses spin faster, which increases the centrifugal force and pushes them outwards.
This raises this sleeve up which in turn closes the valve to reduce the amount of steam entering
the engine. So the centrifugal governor acts as a sensor to provide direct mechanical feedback
to control the speed of the engine. It is one of my favorite inventions of the industrial
revolution. Thanks for watching till the end everyone. Hope you liked the video and feel
free to ask me any questions on twitter.

100 thoughts on “Can We Create Artificial Gravity?

  • This was fascinating… at risk of repeating a question from way down below, if ring is not Elysium sized but 2001: ASO station sized, or perhaps a wee bit smaller, the issue with blood rushing to feet sounds like a major problem. This would, I imagine, have a lot of health risks?

  • Over the life of the F-35 fighter jet it will cost tax payers over a trillion dollers so we can afford it apparently

  • But gravity doesn't exist!
    – Just ask any Trump supporter.
    Oh, and the Earth is flat.
    And the coal industry is coming back.
    And the US economy s doing great.

  • Economics 101. RESOURCES are limited. The cost of space travel is constant because the amount of energy it takes to get that limited resource to LEO.
    Given that the shuttle never made it out of prototype, we don't have a commercial estimate, that is until SpaceX.
    Either way, man semi/permanently in space is still a work of fiction.

  • *Simply too expensive*. the the US, EU, Australia and Canada spend over a trillion a year on defence. I’m sure we could afford to build this.

  • … centrifugal force isn't a force. CENTRIPICAL force is a force it's just the actual name of the force you're thinking of

  • If you make the circle have pods on each sides with a completely flat floor you get rid of most of your problems.

  • 1:18 "In this reference frame centrifugal force is absolutly a real and measurable force" : so a supposed physical force that is unreal in one reference frame, may becomes physically real when you change the reference frame. Interresting.

  • 1:38 "If centripetal force exist in this reference frame, there has to be a force pushing him outwards, that is centrifugal force". No.
    But where is the centripetal force ?
    First of all:
    If we imagine the situation in space and without rotation, there will be no centripetal force that will push man towards the centre. Some may think of the soil reaction… but so it will mean that the soil reacts to the weight of the man… while we are in weightlessness. The man will not press on the soil. And if he tries to do so with his muscles, the soil will react in any direction depending of the direction of the pressure, not in a specific centripetal direction. So there's no specific centripetal force in this situation.
    Then :
    If we rotate the thing, there is still no centripetal force, why would it suddenly appear ? But the soil will pushe the man tangentially to the circle, and this at every moment. On the other hand, by inertia, his body should go straight into space, like the stone of a slingshot, but the ground prevents him from doing so, and then he can then believe he is undergoing a force of gravity or a centrifugal force, but he is not.
    His sensation is not subjected to a force whose direction would be centrifugal, but to a frictional (and tangential) force due to the motion of the ground.
    And in fact, the man will be able to do many experiments to discover he is in a rotating system, if he drops his pen he will see that it doesn't fall back at his feet, etc.
    What's really unfortunate is that you're talking about "angry mobs" who say centrifugal force doesn't exist. It's about science and arguments, there's no reason to be "angry".
    We have all learned in school that centrifugal force, or that hot air is lighter than cold air. And then, listening to a particular scientist or reading a particular popularization article, we realize that these were simplifications of language, which do not correspond to reality. However, these simplifications only make things more complicated, because they introduce misconceptions that sometimes do more harm than good. It is not "angry" to give a more real vision of things, if it is done with politeness and arguments, perhaps sometimes clumsy, I do not claim to be a scientist.

  • Thank you.  I've always wondered why a rotational Station hasn't been done.. yet.    Of coarse, in space, the 'Spokes' could be 100th the size.. etc.   Anyway, by the time we brought it up there, the Ball Reactor in Nevada, you know, the one that 'repels' human touch.. it might be revealed by then and then people would say.. FU**, why didn't you show us THIS back in 2012?

  • Centrifugal is not a real force but a psudoforce. They say its not real but they mean its not real gravity, not that it wont work. You have over 2 million views on this vid? Thats beyond my comprehention.

  • it's a far cry from regular gravity. release a pebble mid-air in such a spinner and the pebble stays in that position, not falling.
    cant we make micro black holes yet?

  • Thanks for the interesting video. What about the counter-rotation problem? The same facing helicopters, as the total rotational momentum should be zero in an isolated system. Maybe in odessy 2001 they had to show 2 parts rotating oppositely. Huum, I have to rewatch the movie 😉

  • I have calculated the size once and to have difference: 0,1 m2/s of "gravitational" acceleration between legs and head of a virtual 2m (6,5ft) high person, we would have to have station with 200m (656ft) radius.

  • did one of the 2.3 million viewers consider that centrifugal force cannot exist outside of a gravity field…..?

  • Sure , lets turn this planet into a polluted bankrupt ball of poison so that we can put some condos in space.

  • Too bad there isn't already a large ball of rock rotating in an orbit around earth- we could build on THAT.

  • Why do we always have to assume that making a large diameter rotating enclosure be of continuous mass? Why can't we simply position two equivalent masses connected by a long cable (or hollow tube in which one can traverse between them) and then set them in rotational motion? The distance between them can therefore be as long as you want with minimal expense.

  • I like to imagine we figure out how to generate strong sustained propulsion over long distances such that, once in space, a ship will be in constant acceleration of 9.8 m/s. When the ship is just over halfway to its destination, the ship will swivel and now decelerate at 9.8 m/s. On long haul flights to other planets or interstellar travel, you could theoretically be on earth-like gravity for most of the journey and hit very high speeds by midflight. The science behind the sustained fuel supply would be rather impractical though…

  • I really like the video and I’m convinced that (the lack of) a viable artificial gravity solution is the primary obstacle preventing humanity from becoming a space-fairing civilization. Without gravity, even the finest ship is inherently hostile to life In all other areas we are making rapid progress. However there are many obstacles with the centrifugal option not highlighted here. For example the need for symmetry (ballast) at all times, especially if the ship is moving toward a destination, to prevent wobble. Is it possible to create a spinning ‘hammer’ (ship on one end, ballast on the other?). How does this affect navigation? Likewise, what options exist beyond these daunting mechanical solutions? Is there any known technology for creating true artificial gravity aside from this mechanical approach(gravity boots, magnetism, etc)? This challenge is the true reason we don’t have bases on other planets and won’t in the foreseeable future.

  • Stop spraying the earth’s atmosphere with aluminum, barium and strontium and you will have more than enough aluminum to use in space projects — “Waist not, Want not,” commanded Jesus.

  • So would 300 meter in diameter be enough to hold the blood circulation normal would much of the blood still go to your legs?

  • Only problem to harvest aluminum on moon as you say , is we can not get there . We have not been there and will probably never get there either.

  • Man.. we need to all get together build a mining and launch base on the moon. Hit mars on our way out the solar system.

  • Just fill it up with air, everything heavier will fall everything lighter than air will float. Gravity is irrelevant/non-existent. Look at the periodic table. Almost everything is heavier that the molecules that make up air.

  • I wonder if the earth stops spinning (without considering Sun's any gravitational effect), would the gravity be more effective on us

  • 360° Artificial Rotational Wheel may more efficient than traditional wheel, Long live mother land…! 🇮🇳

  • As the mass of human body in space is close to none and the gravity of any ship will be close to none then it's not possible to create the centrifugal force based artificial gravity. The body will float no matter how fast the structure will spin.

  • As an A level student many years ago, I remember the physics teacher saying ‘there is no such thing as centrifugal force, it is actually centripetal force’.

  • We could put a test station with artificilal into space very cheaply. Just use a long tether with a counterweight. It would be a great test bed to see the effect on humans.

  • I really don't understand the argument that the space station must be huge. A smaller spinning space station would not have as good a fake gravity as a a huge one, but it would still be a whole lot better than zero G.
    And the space station need not be a spinning disk. Two separate masses connected by a truss or cable spinning would work just fine.

  • They could use balloons like they already do. Not to mention anti-gravity ships like the tr3b and the Aurora type of ships. I forget what the giant Boomerang shaped ones are called right now. They already have them up there anyway. Do a little research jerk. LOL.

  • Hey thanks so much for making this video. It really inspired me and helped me come up with my concept for artificial gravity for the SpaceX Starship. Let me know what you think:

  • Prices can be controlled, just don't pay rather make it a obligation to agencies to accomplish it. Or make it though crowdfunding..just offer the fund fillers some amount of time in ratio of their donation to this project monetarily or volunterly

  • If you had water in a hamster wheel made of wood planks, the water would not follow around the wheel dude. It would float off that wood. No matter which way or how fast its going. If gravity were involved it would just sit and splash around towards the botom of the wheel, it wouldnt go up and around

  • Considering that the U.S. is 22 trillion in debt, seems like a worthwhile project. At least there would be something to show for all that money.

  • For someone called Real engineering… at least do your math right would be an start… for second .. you lost countless variables in your estimate as well… so even if the math was right.. for part you thought of , would still be miles and miles off as missing variables not in counted for ….

    Just sad… 2mil subs,, and cant do math on channel that generally is about math and its applications in real world.. the state of U.S schooling system… and hardly anyone even noticed your mistakes… even more sad..

  • Uh but, in space this doesn't work if you jump you'll fly to the other side of the wheel. Water doesn't fall and float . An air hockey table floor that suck will have the idea of gravity

  • If we could discover a new stable isotope or element that could create artificial gravity we could possibly create another sort of aircraft that uses gravity to push itself through a space ex. water, air or the space outside of earth's atmosphere, it could then achieve high velocity and we could go to mars in a matter of minutes maybe seconds! So fascinating this kind of stuff!

  • Assuming there's enough material in space to build that ship all we need to do is transport the ship building machinery to the moon (or another planet). We get free material, no risk of material price inflating due to demand, lower gravity as compared to earth so lower launch cost.

  • How about we dont launch the space craft, we build it in space, then put air in it with plants. Then you can easily make air-jets for the outside. which will slowly bring it up to rotational speed. Build the base ring and then expand and hopefully we will have a Halo, because thats what the game Halo is partly based on. Planet sized rings with their own atmosphere

  • We’re living on a space ship. Why are we looking towards space when all the answers are beneath our feet. Answer: Because the truth is hidden. Can’t wait for the younger generation to take over.

  • The cheapest solution would be to produce and launch elysium 3D printed and assembled from a factory based on Moon.

  • See an amazeing video of a spaceship concept with this type of artificial gravity:

  • Yeah great Idea rob earth of material which = mass, which gives us a specific Gravity, which keeps us a specific distance from the sun. Yeah and NASA is smarter then me, ha ha

  • This will happen once we colonize the moon and have infrastructure there to produce metals. Then the launch cost go way down.

  • Acceleration isn't directly proportional to the distance from the centre of rotation, rather it is inversely proportional – where an increase in distance will invertedly reduce acceleration. The formula; mv^2/r is here for reference.

  • Okay. Says centrifugal force is real, but only if we lie to ourselves and use funny reference frames. Seems real to me. Lmao.

  • Well now you need to fix your computation cuz elon musk is just created a reusable spacecraft which will greatly reduce cost.

  • Where’s the evidence of the ISS being assembled in space? Records of the 36 launches? Not on the FAI website, I can tell you that!

  • The other large problem, not mentioned in the video, is that you need a fixed point, a source of leverage, around which to create that centrifugal spin. All of the spinning objects shown in the video are attached to something at the middle, allowing the outer structure to spin. In space, there would be no point of leverage around which to spin. Even if you put 1000 rockets around the perimeter, all facing and firing in the same direction, you wouldn't be able to control the oscillation in a single plane, which would be needed to keep it stable, and the structure would likely rip itself apart from the massive torsion created by the uncontrolled oscillation.

    If you could somehow overcome all of these issues, then centrifugal force could absolutely create the kind of artificial gravity in space that was proposed in the video. Unfortunately, I have yet to see or hear a good solution for the aformentioned problems, so it remains a largely moot point.

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