If Gravity Could Be Temporarily Cancelled How Much Cheaper Would Space Travel Be?

[Spacescifi]

Scifi scenario: We have a natural unobtanium ore that when magnetized for a period of time will charge up a gravity cancellation field. Which can be discharged over a period of time.

Unobtanium: About as rare as uranium and just as expensive.

Stats: The more mass of unobtanium you have the larger the gravity cancellation field you can create. For example, a ton of it would allow you to cancel gravity in a kilometer wide sphere of influence.

Refined unobtanium is expensive as weapons grade uranium and also allows for longer charging of gravity cancellation fields. You need a planet with gravity to charge it first, far away from one it would not work.

Discharging: Generates the gravity cancellation field until it runs out of charge. How long? Refined unobtanium can get you an hour at max, unrefined will only get you six minutes before you need to charge again.

Charging and discharging takes equal amounts of time and is done automatically. Meaning after charging you will automatically begin discharging the gravity cancellation field, since it can only be stored while charging.

Since this is so, rockets only charge for how much time they need to reach orbit and no more.

Utility: Launch/landing is cheaper but by how much is what I want to know? SSTOs become popular... do we even use TSTO anymore? Cool thing is you can land/launch on several terrestrial planets easily now.

Also spin launch from Earth is suddenly more effective, as a way to save propellant for launch/landing.

Space Market: Space resources are still expensive but now that they can be brought back to earth more effectively reaping profit off rare earth metals is easier. Stuff like platinum etc.

Edited April 22, 2023 by Spacescifi

[magnemoe]

You would save the gravitation losses of getting into orbit. However orbit is fast not high so this will be much less useful than you imagine.

 

[Spacescifi]

1 hour ago, magnemoe said:

You would save the gravitation losses of getting into orbit. However orbit is fast not high so this will be much less useful than you imagine.

 

 

I see.... so without a pulsed fusion detonation rocket or project orion, two staging is still in use. You need either scifi or future theoretical rocketry involving fusion to get SSTOs of any high mass.

[StrandedonEarth]

What's needed is a Kzinti-style gravity planer/antigravity. 

[kerbiloid]

Zero cost.

The air gets away in minutes, so you are in space right where you are standing.

[Superfluous J]

Cost to orbit would not be all that great, but if you could turn it off and on at will cost to the Moon could be lowered greatly.

Turn it on, 0 gravity. Aim for the Moon (or thereabouts, orbital mechanics and whatnot) and fire.

Once near the Moon, turn it back on to start getting pulled in/around. At Pe (if possible) turn gravity UP and you can get into orbit.

And why limit yourself to 0 gravity? You invented this stuff, why not let gravity go negative? Then your ship would just start falling away from the surface of the planet.

[kerbiloid]

https://en.wikipedia.org/wiki/The_First_Men_in_the_Moon

[Spacescifi]

39 minutes ago, Superfluous J said:

Cost to orbit would not be all that great, but if you could turn it off and on at will cost to the Moon could be lowered greatly.

Turn it on, 0 gravity. Aim for the Moon (or thereabouts, orbital mechanics and whatnot) and fire.

Once near the Moon, turn it back on to start getting pulled in/around. At Pe (if possible) turn gravity UP and you can get into orbit.

And why limit yourself to 0 gravity? You invented this stuff, why not let gravity go negative? Then your ship would just start falling away from the surface of the planet.

 

With timing of the charge/discharge you can.

Negative gravity is kind of overpowered. Especially with no limtations. If you just 1g fall away from earth you get up to ridiculous speeds in space since it takes a great distance before Earth's gravity is much weaker than 1g. Even at LEO distnce 1g gravity strength is about 98%.

Edited April 22, 2023 by Spacescifi

[NFUN]

Much much cheaper. As people have noticed, this doesn't help you orbit which is the hard part, but it does let you completely ignore most of the hard parts about rocketry. You don't need to worry about high thrust or aerodynamics, so you can let a big steel sphere of fuel with a base attached float to space and slowly achieve orbital velocities with some dinky little thruster and be fine

[RCgothic]

The DV needed to establish orbit would drop from about 9.3km/s including of gravity and aero losses of ascent to the pure 7.8km/s required to maintain orbit. So in DV terms it's not much.

However, as others have stated you could get away with much smaller engines. Taken to extremes, you barely need any thrust. Stick the highest ISP/low thrust ion thruster you can find on your ship and you'll get to orbital velocity eventually. Structural margins and dry mass would be enormously reduced. The rocket would be a lot smaller.

[razark]

If you want SSTOs in your story, just write them in without coming up with magic solutions.

[Spacescifi]

1 hour ago, RCgothic said:

The DV needed to establish orbit would drop from about 9.3km/s including of gravity and aero losses of ascent to the pure 7.8km/s required to maintain orbit. So in DV terms it's not much.

However, as others have stated you could get away with much smaller engines. Taken to extremes, you barely need any thrust. Stick the highest ISP/low thrust ion thruster you can find on your ship and you'll get to orbital velocity eventually. Structural margins and dry mass would be enormously reduced. The rocket would be a lot smaller.

 

Per the OP won't be super cheap. Since you need a literal ton of unobtanium as a expensive as refined uranium, which will give an hour at max to reach space to do an orbital burn before you run out of gravity cancellation field and have to charge it for an hour or less if you need it again for however long.

[lajoswinkler]

Turn it off (for the ship; the rest of us need gravity for air pressure LOL), you get very high with ease. If you want to turn it off and stay there, you have to accelerate to first cosmic speed. So, turn off, get up there, accelerate, turn back on.

However, what does it mean "to turn it off"?Turn it off for the ship in relation to Earth? What about the Sun? I assume you don't want Earth to escape beneath you.

This is more complicated than it seems.

[Spacescifi]

43 minutes ago, lajoswinkler said:

Turn it off (for the ship; the rest of us need gravity for air pressure LOL), you get very high with ease. If you want to turn it off and stay there, you have to accelerate to first cosmic speed. So, turn off, get up there, accelerate, turn back on.

However, what does it mean "to turn it off"?Turn it off for the ship in relation to Earth? What about the Sun? I assume you don't want Earth to escape beneath you.

This is more complicated than it seems.

 

Not really complex because inertia is still present. As long as an object is in the atmosphere it's speed I don't think will change quickly.

[Nuke]

depends on how fast you want to go. things are still far enough apart where direct point to point flat trajectories will still take an eternity without an expensive engine. of course if you get to the point where you can do fast point to point trajectories, gravity will be nothing more than a mild inconvenience. 

[Shpaget]

This would finally be viable.

Which should tell you everything you need to know about "legality" of your idea.

[Hannu2]

On 4/22/2023 at 11:36 PM, Shpaget said:

This would finally be viable.

Which should tell you everything you need to know about "legality" of your idea.

That kind of phenomena is conflicting with conservation of energy. Perpetual motion power generation would be much more profitable application.

It may be little bit tricky to find such material but there is no other reasoning for conservation laws (or symmetries behind them) than observations. At Universe level conservation of energy does not necessarily hold. Expanding Universe gets energy for nothing and share of "dark energy" is increasing. We do not know what is behind that but what we have observed is not compatible with conservation of energy in observable Universe. 

[Dunas Only Moon]

Ok, gravity is what holds things together, without it, we would die.

End of thread

[NFUN]

14 minutes ago, Dunas Only Moon said:

Ok, gravity is what holds things together, without it, we would die.

End of thread

you should read the OP and a science textbook before trying a post like this

[Dunas Only Moon]

On 5/3/2023 at 10:32 AM, NFUN said:

you should read the OP and a science textbook before trying a post like this

oh, my mistake, i misread the post, apparently, it would fling anything in the field into deep deep space, as gravity is what holds things down, and because the earth, the sun, and the milky way are all moving, you would be flung into the unknown. so unless you find the perfect amount of this unobtainium to fling you perfectly into space (maybe a microgram [or is that too much ]) to get you low enough to be in earths gravity well, and high enough to get yourself out of the atmosphere, so it might cost just as much as being teleported high up without any speed.

Edit: every atom would vaporize and also be teleported far out

Edited May 8, 2023 by Dunas Only Moon

[sevenperforce]

On 4/22/2023 at 1:42 PM, razark said:

If you want SSTOs in your story, just write them in without coming up with magic solutions.

Well, begrudgingly to @Spacescifi's credit, this is one of the only workable magic solutions he's come up with so far.

And it matches most of the depictions of levitation and spaceflight in science fiction.

[razark]

8 minutes ago, sevenperforce said:

And it matches most of the depictions of levitation and spaceflight in science fiction.

 

Quote

 

Werner Heisenberg's "uncertainty principle" suggested that on a subatomic level, it is possible to know the motion or the position of a particle, but not both. Some believe this fundamental characteristic of matter would make it impossible for a transporter to work as shown on Star Trek. The Heisenberg compensator was invented to circumvent this principle and to explain how the transporter can work. (Star Trek Encyclopedia (4th ed., vol. 1, p. 333))

When asked by Time magazine in 1994, "How do the Heisenberg compensators work?" Michael Okuda replied, "They work just fine, thank you."

 

 

[kerbiloid]

2 hours ago, razark said:

Werner Heisenberg's "uncertainty principle" suggested that on a subatomic level, it is possible to know the motion or the position of a particle, but not both. Some believe this fundamental characteristic of matter would make it impossible for a transporter to work as shown on Star Trek. The Heisenberg compensator was invented to circumvent this principle and to explain how the transporter can work. (Star Trek Encyclopedia

A Heisenberg  Apathy lemma: "Both motion and position may stay unknown at once, if the Observer doesn't give a ... care."

***

2 hours ago, sevenperforce said:

begrudgingly

My inner lingwist will never be the same after knowing this word...

Edited May 5, 2023 by kerbiloid

[Arugela]

Wouldn't you just have to jump and have something to stop you. At least once the oxygen is out of the way. Probably keep jumping in one place repeatedly until you make it. Without suffocating that is.

It would technically be free. But you would have to expend time to get it to where you wanted based on the force you can exhert on it. So, it would just be a matter of time. 8)

Unless the ground stopped being a good jumping point. Then you might need to get down to bedrock or something sufficient that is more solid than you I'm guessing.

Or as the earth might still be moving, A matter of being ejected naturally as everything leaves based on the force being exherted by the planets as gravity stops working and we all fly off in different direction. So, again, a matter of time. And somewhat direction.

And there would be no more orbit. Orbit is the result of gravity(presumabely). It would be a matter of being ejected into space based on the previous values. Space travel would cease to be an option. It would become the norm... Or am I missing something?

And if ground and air mixed around it might shred you to pieces and continue on. But it would end in the same thing I would think.

The real question is how to keep the change in your pockets. And whether or not the appendix vermicularis stretcher still works. (Cause you might need it for a little thrust management.)

On 5/3/2023 at 10:32 AM, NFUN said:

you should read the OP and a science textbook before trying a post like this

If we don't know what causes gravity we don't know the answer to that. If the forces related to holding atoms together is also related to gravity it could happen. As is we don't know anything works. It's just all theory. Keep an open mind.

Edited May 28, 2023 by Arugela

[KSK]

8 hours ago, Arugela said:

If we don't know what causes gravity we don't know the answer to that. If the forces related to holding atoms together is also related to gravity it could happen. As is we don't know anything works. It's just all theory. Keep an open mind.

"But not so open that your brains fall out."  Popularly attributed to Carl Sagan.

Properly speaking,  a theory is a hypothesis backed up by empirical, falsifiable, evidence.  Saying that something is 'just theory' is not at all the same thing as saying that we don't know anything about it.

Thought experiments are a valid way of thinking. In other words, even if we don't know what causes gravity (which is a whole other debate), we have observed what gravity causes and can infer what would happen if gravity wasn't there.

In this particular case, we have observational evidence for various kinds of matter in the interstellar medium - i.e.  in as close to a genuine zero gravity environment (as opposed to freefall) as it's possible to get.  If the forces holding atoms together were related to gravity, or if a lack of gravity means that  'every atom would vaporize', then we would not expect to find an interstellar medium.

We may not know precisely how gravity works but we have a very good theory for it (general relativity) and, more importantly, we know the limitations of that theory because of its inconsistency with a second theory (quantum theory, which I'm using here as a general term for a lot of related concepts and mathematical frameworks). Both theories are backed by solid bodies of experimental evidence. Quantum electrodynamics for example, which deals with the interactions between light and matter, gives results which agree with the most accurate experimental measurements we can make.

Any new theory which purports to better explains how gravity work would need to a) be consistent with the experimental evidence in support of both general relativity and quantum theory, b) reconcile the differences between the two, and c) be backed up by experimental evidence of its own. That's a high bar to clear.

Handwaving those requirements away with an airy implication that 'we don't know how anything works, therefore anything is possible' is, at best, screamingly unscientific and in my experience, either a sign of internet crackpottery, or a sign that a vested interest is spreading FUD in defiance of all evidence to the contrary. 

 

 

Edited May 28, 2023 by KSK