# Thread: Would A True Reactionless Drive Make G Force No Longer A Problem?

1. As everyone who has ever researched it knows, G force prevents humans from traveling as fast as they could go in space. Travel 3 G's or more and it will do damage to the body after prolonged periods of time.

Simply because our bodies are made to withstand 1 G (Earth gravity force), and not higher levels.

So I was thinking, a true reactionless drive would not have a reaction force (it's not throwing anything out the back to accelerate), which should mean that crewmembers won't experience ANY G force even at high accelerations.

So by that theory, you wouldn't even need inertial dampeners like they use on star trek, since the reactionary force simply isn't there.

Am I right or wrong?

And while I know it's impossible, this is science fiction, so I am free to indulge the impossible here.

2.

3. Well, if it's an unknown science that is making the acceleration unfelt to the ship, then sure.

By the way, humans can travel as fast as they want in space. The G's come from acceleration, not speed.

4. Originally Posted by lorbo
So I was thinking, a true reactionless drive would not have a reaction force (it's not throwing anything out the back to accelerate), which should mean that crewmembers won't experience ANY G force even at high accelerations.
G force comes from acceleration, not from the rocket. (Note that you can feel it in an elevator, even though there's no rocket or reaction drive.) You'd still feel the G's as you accelerated.

5. Originally Posted by pyoko
Well, if it's an unknown science that is making the acceleration unfelt to the ship, then sure.

By the way, humans can travel as fast as they want in space. The G's come from acceleration, not speed.
So Star Trek goofed when they put in the inertial dampeners, just like I thought! LOL.

When you try to mix current physics understanding with the impossible, inconsistencies become inevitiable I suppose.

A lot of Trek ships appear to use reactionless drives, yet they use outdated fustion reactors to power them.

For science fiction, you may as well go ALL out.

Science Fantasy so be it. Just not the Star Wars route where you start making up stuff like the force.

But now I love reactionless drives, as they are an ALL IN ONE type of technology. They have so many applications and make space travel a real breeze.

6. Well actually, we already have one.

The Alcubierre drive is essentially a reactionless one, since it bend contracts space time and expands it out the back.

No G force effects happen whatsoever.

You can use it sublight speeds just like you can at FTL speeds, so there is no reason for an Impulse drive. The warp drive can do it all.

7. [QUOTE=lorbo;515224]
Originally Posted by pyoko
So Star Trek goofed when they put in the inertial dampeners, just like I thought!.
Given that they use something called "impulse engines" (a reference to a reaction engine) - sounds appropriate.

8. Actually, scientists have figured out that if even if they made a functioning Alcubierre drive, it couldn't fly at light speed, let alone FTL.

Doing that creates hawking radiation at the center of the ship, hot and deadly stuff which kills.

Going at sublight speeds creates no such problem.

Which means it's still better than using rockets.

So for a science fiction angle:

Use Alcubierre drive for sublight travel and hyperspace tunnels for FTL. Hyperspace tunnles are great since they avoid a lot of the issues with space and relativity.

9. "Outdated" fusion reactors? You realise fusion is still basically a thing of the future, right? We are still stuck with fission. And they also have a "warp core" that has unknown physics behind it.

10. Originally Posted by pyoko
"Outdated" fusion reactors? You realise fusion is still basically a thing of the future, right? We are still stuck with fission. And they also have a "warp core" that has unknown physics behind it.
Reactionless drives, which is how Star Trek ships fly despite their claim to use reaction thrust (which would be quite noticeable if properly depicted), I would argue require something much more powerful than fusion.

And thus the warp drive was born. Perfect for sub-light travel. FTL? Forget it. That's what hyperspace tunnels are for.

11. But we do not know whether "more power" is what is needed to go FTL. It may as well be not more power but simply physics that we do not know yet. "More power" seems like a very primitive way to try and force this idea. For all we know a 9V battery might be able to power such a device.

12. Originally Posted by billvon
G force comes from acceleration, not from the rocket. (Note that you can feel it in an elevator, even though there's no rocket or reaction drive.) You'd still feel the G's as you accelerated.
Let's keep that elevator in mind for this sci-fi speculation. What's the problem with G force really? Say you're in free fall, accelerating due to gravity. Is it the fall that hurts you, or the sudden stop at the bottom? Try dropping your elevator into Jupiter. Even greater acceleration, yet it feels no different than orbit. Just how much acceleration due to gravity can a human withstand? No limit.

The sci-fi drive should generate gravity, or a practical facsimile of it, through the entire spacecraft including its contents.

13. Originally Posted by Pong
What's the problem with G force really?
Well, lots of it will kill you, a little less will cripple you, a little less will cause you pain and injury. Main problems.

Say you're in free fall, accelerating due to gravity. Is it the fall that hurts you, or the sudden stop at the bottom?
The acceleration hurts you. (Seeing a 100G acceleration due to impact is no different, physiologically, than seeing a 100G acceleration due to a rocket under the elevator.)

Try dropping your elevator into Jupiter. Even greater acceleration, yet it feels no different than orbit. Just how much acceleration due to gravity can a human withstand? No limit.
"Acceleration." You keep using that word. I do not think it means what you think it means.

The sci-fi drive should generate gravity, or a practical facsimile of it, through the entire spacecraft including its contents.
If you can do that and counteract the acceleration caused by the rocket, that would work. However in general it's not necessary at least for interplanetary travel - if you can accelerate at ~1G (quite comfortable) you can get places very quickly:

4 hours to the moon
2 days to Mars
9 days to Saturn
16 days to Pluto

14. Originally Posted by billvon
"Acceleration." You keep using that word. I do not think it means what you think it means.
I think you mean the difference between the craft and the human occupant. For example the "G force" of a seat thrusting against your back.

I'm using it in the sense of acceleration due to gravity. For example the acceleration of a spacecraft slingshot around a planet. In this case the occupants don't feel any forces relative to their craft... they may float a pencil in the air and it won't move much though the entire exercise... though it's being greatly accelerated.

If your sci-fi drive can create gravity, you can comfortably accelerate at any rate.

15. Originally Posted by Pong
I'm using it in the sense of acceleration due to gravity. For example the acceleration of a spacecraft slingshot around a planet. In this case the occupants don't feel any forces relative to their craft... they may float a pencil in the air and it won't move much though the entire exercise... though it's being greatly accelerated.

If your sci-fi drive can create gravity, you can comfortably accelerate at any rate.
I'd never thought of that before. Clever.

Originally Posted by pyoko
For all we know a 9V battery might be able to power such a device.
Every time you lick a 9V battery to test its charge, relativity dies a little inside.

16. Originally Posted by Pong
Originally Posted by billvon
"Acceleration." You keep using that word. I do not think it means what you think it means.
I think you mean the difference between the craft and the human occupant. For example the "G force" of a seat thrusting against your back.

I'm using it in the sense of acceleration due to gravity. For example the acceleration of a spacecraft slingshot around a planet. In this case the occupants don't feel any forces relative to their craft... they may float a pencil in the air and it won't move much though the entire exercise... though it's being greatly accelerated.

If your sci-fi drive can create gravity, you can comfortably accelerate at any rate.

So gravity drives are the only thing you need for a science fiction FTL drive.

You don't want or need rockets. Just gravity drives.

Which brings us to the question, how do they react to planets?

Say you wanna launch one off a planet? Will that cause any adverse effects?

Every action has a reaction, and I suppose that if the gravity drive is shooting out repulsive gravity like a rocket, it might move a planet off course, which would be catastrophic.

So gravity drives would be treated like Nuclear reactors, and ordinary people would not own any, due to the danger. A gravity drive could also explode and very likely bust a planet.

These powers are ridiculous, but it's good to keep in mind that the power needed for science fiction seems to, by all accounts, require much more than we are used to.

Which means mankind would finally be superior to nature, at least in the sense in that his tech would be more durable than planets, assuming they had good enough deflector shields.

Otherwise you have a MAD scenario, where the science fiction has zero flashy battles because it's suicide.

17. Originally Posted by Pong
I think you mean the difference between the craft and the human occupant. For example the "G force" of a seat thrusting against your back.
Acceleration acts the same on a craft as on a person. Enough acceleration will kill a person or crush a craft.

I'm using it in the sense of acceleration due to gravity. For example the acceleration of a spacecraft slingshot around a planet. In this case the occupants don't feel any forces relative to their craft.
Nor does the craft. Neither the craft nor the occupant accelerate; they are in freefall, moving along a geodesic in the curved spacetime near a planet. From their perspective, they are moving in a straight line, neither accelerating nor decelerating.

If your sci-fi drive can create gravity, you can comfortably accelerate at any rate.
Agreed there. Since gravity and acceleration are indistinguishable, you could use a 9G artificial gravity source to make a 10G acceleration feel like a 1G acceleration.

18. For examples of how a gravity drive might work, see any hypothesis for "push gravity". A gravity drive needn't employ real gravity, just a practical facsimile of gravity... which is just what all those push gravity schemes explore.

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