Artificial gravity 2.0

I asked this already, i just don't know how to move topics. Anyway, on "misapplied phlebotnium" page, it is mentioned if you can control gravity you can create you can create shields, inertial dampeners, tractor beams, and engines. What are ALL of the applications of artificial gravity? And how would they be achieved?

That's a rather broad question, and one that's ultimately unanswerable because we don't have a tangible scientific description of "artificial gravity". We have hypotheses, speculation, and a whole lot of science fiction to fill in the gaps with good old fashioned creativity. I'm merely a dabbler in hard physics, so take what I'm saying as the writings of an educated layman, not a professional scientist.

First, let's get a few things clear about our definitions. We already know how to produce artificial gravity in one sense: spin something and stand on the inside — aka, Centrifugal Gravity. Easy, cheap, and seen in amusement parks around the world. Of course, this is just using inertia to create an acceleration force that makes us feel like we're experiencing gravity; it's not curvature of the fabric of spacetime.

We also already know how to create "real" gravity — what you need is mass or its energy equivalent. Any amount of mass-energy, even a single photon, creates spacetime curvature. However, it takes an enormous amount of mass-energy to produce appreciable gravity. To get 1 g (what we're used to on Earth), you need a rocky ball with a mass of 5.972 × 10^24 kg and you need to stand 6,378 km from its center. You could also concentrate a powerful set of laser beams at a central point and pump in 5.37 × 10^41 J of energy, and you'd have the equivalent spacetime curvature... for a few thousandths of a second, until the laser light went on its merry way into space. Aliens observing the event from a few hundred light years away would wonder how our sun went supernova. (For bonus points, if you focused the lasers into a spherical radius of less than 9 mm, you'd create a black hole).

In another thread, I did some estimates on what you'd need to generate a field of 1 g at a radius of 10 m. The answer comes to about 1.5 x 10^13 kg of mass equivalence, which if contained in a 10 m radius sphere would be about as dense as a white dwarf star.

Clearly the mass-energy curvature method is out as a means of generating casual artificial gravity. So what we're left with is some sort of sci-fi mechanism for manipulating gravity itself. Some have suggested that this could come about through manipulating the Higgs field, which gives particles (some of their) mass. Others propose that it could be a result of the discovery of the Theory of Everything — an equation that unifies quantum mechanics and general relativity and solves the mystery of how gravity operates at the quantum level.

The Holy Grail, if you will, is the ability to create gravitational fields — spacetime curvature — without the concentration of mass-energy that they usually require. If we can do this, then the sky is the limit. Or not even the sky: the universe. All kinds of fantastic rule-breaking becomes possible, since you'll have broken quite a few physical laws that we thought were absolute, such as conservation of momentum and symmetry.

Fine, what you want is applications, not an armchair physicist babbling about theories. Let's talk...

• Shields, sure. If you can create gravity fields you can bend incoming projectiles, even light, away from an object.
• Artificial gravity. Well, duh, but if you want to be able to walk around normally on the side of a building, or a 100 m long spaceship, you're good.
• Inertial dampers: Obviously. You could negate the inertial effects of acceleration on objects, or just create a gravity field to accelerate them. (FYI, it's "damper", not "dampener", unless you're suggesting inertia can be made wet.)
• Fantastic weapons. You could compress spacetime around any object, irresistibly squashing it down until it's a soup of subatomic particles. Call it the "spaghettification gun".
• Unlimited power via artificially created black holes, from which you'd harvest Hawking radiation.
• Nucleosynthesis — creating heavier elements from lighter ones — via controlled fusion reactions. Want gold? Americium? It's just a matter of the right gravitational pressure and temperature.
• Starships capable of traveling near the speed of light due to gravitationally-assisted acceleration, or if you aren't that exotic, antimatter drives. Yes, artificial event horizons are a great way to harvest antimatter.
• If you can figure out how to create negative gravitational energy, you've got an Alcubierre warp drive — i.e., FTL. Here's hoping Unruh radiation doesn't fry you.
• Geo-engineering of unprecedented scale. Want to turn the Earth into a donut shape for kicks? You got it.
• Solar engineering: sculpt stars to your specifications. Turn stars on and off.
• Rearrange the orbits of planets. You could pop over to the Alpha Centauri system in a year or so (subjective transit time) and spell out dirty words with its planets.

Interstellar shows a few of the applications of artificial gravity, but also throws in a few purely fantastical bits that don't make sense even with command of that force. For example, once you're inside the event horizon of a black hole, that's it. You aren't coming out again even with space magic. You can mess with where the event horizon is, however.

edited 20th Apr '18 6:28:35 AM by Fighteer

Holy shit.

So basically, if we in the real world, ever discover how to creat artificial gravity, basically our entire way of life changes literally over night.

It'd be The Singularity, both literally and metaphorically.

Hence why my Artificial gravity is severely limited in scope or stuck to interiors in a vacuum environment.

Or requiring of mass power and barely understood for my Mecha novel.

In the first verse you could probably use artificial gravity for power generation.

Oh yeah certain conditions are easily used to make a proper containment unit for Fusion power.

That's what happens in the Mecha novel as well, with what the Earth Forces understand about the artificial gravity units and their own attempts, they manage to make working fusion reactors for space ships.

The thing about "true" artificial gravity in the sense we're describing is that you're inherently violating conservation of energy by getting more work out than you're putting in. The only way this could happen in reality is if you're tapping into some additional energy source that we can't normally access.

This is why I've thought about the ideas of string theory, including extra "compactified" dimensions, and whether they could be the source of this energy. We don't know that they can't, which is good enough for science fiction. (Vacuum energy won't do because it's at a constant density throughout the universe and work requires an energy gradient.)

Imagine that there's a hidden, low-entropy state hanging out in some extra dimension. It's metastable, meaning that it is kept from dropping into a lower energy state by some barrier. Breach that barrier (via some kind of phlebotinum), and its potential energy would flood out into other fields, giving you "free" energy. Controlling it would be tricky, but hey, that's what you do in fiction.

edited 19th Apr '18 5:31:33 AM by Fighteer

How are you violating conservation?

You are creating a force equal and opposite to the gravitational attraction of a certain mass. Where is that energy coming from? A mere nuclear reactor isnt even going to come close.

You mean you're creating mass out of nothing?

In a closed system, there exists gravitons. As long as the number of gravitons remain the same you can use those gravitons to increase mass.

Other applications of artificial gravity.

Warp drive Synthetic gravity Inertial dampeners Kinetic shields Tractor beams Propulsion Telekinesis Time manipulation Particle beam weapons Coilguns and Railguns Fusion reactor

Gravitons are a theoretical particle that we have yet to detect experimentally. Our models suggest that they must be incredibly small, but until we get that Grand Unified Theory that I mentioned previously, we won't have any exact predictions. We also don't know that we can generate or control them. By way of demonstration, we have detected the Higgs boson (the force carrier of the Higgs field), but we can't use it to give things mass (or take it away) because it doesn't actually govern the interactions with the field. It just shows up when the electromagnetic and weak nuclear forces merge at super high energy levels.

The reason that sci-fi artificial gravity violates conservation of energy is that it seems to put in less energy than it extracts in terms of work.

As I calculated above, to get gravitational curvature equivalent to 1 g at a radius of 10 m, you need about 1.3 x 10^30 J, or 310 trillion megatons of TNT worth of energy. So sci-fi ships that are doing that must be cheating somehow.

edited 15th May '18 7:41:58 AM by Fighteer

Maybe there are easier ways to warp spacetime than to just dump a bunch of energy/mass into a big pile?

Or maybe they aren't actually generating real gravity wells at all, and just simulate/resist gravity through some other method? I can do a pretty good job resisting and temporarily overcoming the gravitational pull of a decently sized planet just using my legs, just saying.

Well, sure. Doing that in space requires that you spin something fast enough for centrifugal forces to apply or continually accelerate at 9.8 m/s^2. That's what I said in my original reply: we know perfectly well how to simulate gravity using good old Newtonian physics. After all, what we think of as "gravity" in our daily lives is actually the electromagnetic force resisting physical compression.

What we don't know is how to make everyone stand normally on the decks of a spaceship that isn't accelerating or rotating, or that's accelerating at something like 100 g. If you want that, you need something more exotic.

Caveat: You can also use magnetic boots to make people's feet "stick" to a floor, but you don't get the physical experience of gravity in that scenario.

Edited to add:

That's exactly what we're talking about. We don't know of any ways to make that happen, and figuring it out would be The Singularity as far as our understanding of the universe is concerned.

edited 15th May '18 8:56:53 AM by Fighteer

There's no way to produce gravity without mass or acceleration. As far as controlling gravity goes There's dark matter And dark energy

Correction: There's no way to produce gravity without mass-energy or acceleration that we know of. Science fiction is about proposing exotic ideas and exploring the ramifications. It's completely fine if you want to have "artificial gravity" in your story, as long as you're aware of the ramifications and decide whether to exploit or Hand Wave them.

Dark matter has gravity, but it's not something we could use to create artificial gravity. It doesn't interact electromagnetically, so you can't hold it, pull it, contain it, or do anything else that might concentrate it enough to be noticeable to us. There's dark matter in and around us right now, but it has no tangible effect on anything other than through its general gravitational pull, which is effectively nil on the scale of our solar system.

Even if you could manipulate dark matter, you'd need the same mass of it as you'd need of normal matter in order to produce any given amount of gravitational curvature, so you don't really gain any benefit.

Dark energy is uniform throughout spacetime, so it has no gradient that could be used to generate or apply a force. It has gravity, but due to having uniform density, it's exactly equal in all directions everywhere, cancelling itself out, except for its relativistic effects which cause universal expansion (anti-gravity). Our most likely current hypothesis is that it's a fundamental property of the quantum vacuum itself. As far as we know, there's no way to manipulate or exploit it for anything.

edited 18th May '18 9:59:59 AM by Fighteer

It still blows my mind that in 2018 when asked what we know about gravity most physicists just be like

¯\_(ツ)_/¯

We know how gravity works with very high precision. What we lack is a formulation of gravity as a quantum field, to go along with the rest of QFT. In other words, we haven't figured out the fundamental mechanism that gives rise to gravity as a force.

Frankly, if you ask scientists how much they know about the universe out of everything that is possible to know about it, they'll give you a very small number. The more we learn, the more we realize we have yet to discover.

edited 18th May '18 9:57:28 AM by Fighteer

Aren't the physicists worried because the Higgs Boson fits into the Standard Model too well? I'd heard that somewhere but couldn't verify it.

I don't know that "worried" is the right term. Scientists (at least, good ones) like being wrong because it means there's something new to discover. They get suspicious when their theories work out too well, because they know from long experience how hard it is to do that. Not a single theory in science so far has survived completely intact — there's always a deeper truth or more detailed glimpse of reality underneath.

I just watched a video from PBS Space Time discussing how a law we thought was fundamental, conservation of energy, was found to be a special case of a more general law. Here. (Warning: that channel is pretty heavy stuff. I don't recommend opening with a video on Noether's Theorem.)

edited 18th May '18 12:21:28 PM by Fighteer

pretty sure Einstein’s theories have been prettt much been unfalsifiable

Huh? No, Einstein's work has been expanded and elaborated on continuously. I knew someone would make the mistake of thinking that, because a theory is superseded by a deeper theory, it was incorrect. That's not always (or even often) the case.

Take Newton's laws of motion, for example. They work fine (and continue to work fine) in ordinary situations, such as you and I encounter on a daily basis. They even work reasonably well inside our solar system. Later, the ideas behind quantum mechanics were first formulated as part of an attempt to make more efficient light bulbs, and relativity got started while James Maxwell was trying to figure out electromagnetic radiation.

Einstein figured out a deeper principle of the universe in his theories of relativity, building on all of that previous work, and of which Newtonian mechanics are a special case that work at low relative velocities. In the meantime, he was very skeptical of some of the ideas of quantum mechanics, which coevolved with relativity. In particular, he refused for a long time to acknowledge that the universe could be non-deterministic. (The famous "God does not play dice" statement.) He famously made a bet with Neils Bohr about the outcome of the "delayed choice" quantum entanglement experiment, and lost.

Einstein also had his limits and made some lucky guesses. When trying to calculate the geometric flatness of spacetime, he ran into a problem that he solved by adding a constant (the "cosmological constant") to bring the equation into balance. He didn't know what it was and thought it was likely to be eliminated by further research. When dark energy was discovered, it fit right into that slot. Einstein predicted it almost by accident.

People have tried for years to disprove the ideas behind general and special relativity, but they always end up being correct. "Unfalsifiable" would imply that they are built in such a way that you can't disprove them experimentally. That is most definitely not true.

edited 18th May '18 8:09:56 PM by Fighteer

Wrong. There are theoretical ways to control gravity. One is with a protational field. Another is with negative mass. And a 3rd way is with dark energy. https://arxiv.org/abs/0712.1649