How long could a human stand 3X gravity

[Gibsons]

Originally posted by: Nathelion
Not all parts of the human body are platic; compare it to software and hardware. If we regard muscles as "software", they could undoubtedly grow stronger and adapt (although there would be a limit to this as well). The basic structure of certain internal organs, such as the aforementioned kidney and liver, and the brain, is not subject to change due to environmental influences, however. Such "hardware" may not be able to withstand the higher gees.

The liver is very plastic. Brain and kidney not so much, but...

In most cases, hypergravity increases collagen synthesis. Text

Mice can survive 3G for 3 weeks, granted they're probably more suited for it than humans
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Here's a 30 minute exposure to 3Gs in humans, no ill effects mentioned in the abstract
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[TitanDiddly]

Originally posted by: Astrallite
You can't maintain continuous acceleration without a crazy (undiscovered) fuel source. You can certainly maintain a lot of speed in space with ease.

On earth, that is very true. However, as long as you apply a constant force in a singular direction, you will constantly accelerate. On earth that doesn't work because air resistance gives every object a terminal velocity. In space, with no matter in your way and the only forces are gravity from the sun, nearby objects, solar wind and other small forces, it is feasable to come very close to constant acceleration. One misgiving that a lot of people make is that constant acceleration = extreme velocity. For the same reason you mentioned, that is very far off. However, with prototype ion propulsion systems, you can achieve an almost constant acceleration, but it's a very, very long wait to get anywhere. Which is fine for a lot of researchers, because as long as their probe is out there, they have a much better chance to get funding.

 

[Gibsons]

Originally posted by: TitanDiddly

Originally posted by: Astrallite
You can't maintain continuous acceleration without a crazy (undiscovered) fuel source. You can certainly maintain a lot of speed in space with ease.

On earth, that is very true. However, as long as you apply a constant force in a singular direction, you will constantly accelerate. On earth that doesn't work because air resistance gives every object a terminal velocity. In space, with no matter in your way and the only forces are gravity from the sun, nearby objects, solar wind and other small forces, it is feasable to come very close to constant acceleration. One misgiving that a lot of people make is that constant acceleration = extreme velocity. For the same reason you mentioned, that is very far off. However, with prototype ion propulsion systems, you can achieve an almost constant acceleration, but it's a very, very long wait to get anywhere. Which is fine for a lot of researchers, because as long as their probe is out there, they have a much better chance to get funding.

I'm pretty sure Astralite was referring in particular to the idea of accelerating a manned spacecraft at significant G for long (years) periods of time. To accelerate at 3G for more than a year would indeed require some crazy fuel source. Ion propulsion is neat, but currently it's not going to get anywhere near 1G. Especially if we assume a massive spacecraft with a few humans and all the equipment, water and food needed to keep them alive for a year or more.

 

[Smilin]

mmm, I guess I'm one of those constant acceleration=extreme velocity guys you mentioned.

An ion drive might be putting out only about as much force as a falling piece of paper but by the time you reach the edge of the solar system you're cruising!


If we want to reach objects outside our solar system in the lifetime of our passengers we're going to need multiple Gs of acceleration to the halfway point the the same deceleration the rest of the way. Developing such an engine and fuel source is going to be one challenge. Having someone live through such acceleration for an extended period is another.

 

[Swedish Avenger]

I haven't read the whole thread, but one valid point is that underwear would have to be alot more supportive 😛

Read 'The Forever War', tons of stuff about G during acceleration over long periods of time (and top five sci fi ever probably).

 

[Matchstckgmr]

Lets say if somebody made a machine that could crate gravity in in one room at any level from 1 to 100 times earth gravity. Could if somebody trained in there for long periods of time and what I mean by training is do there normal routine but in higher levels of gravity even work out. could they get used to higher levels of gravity over time and possibly even move in there freely as they do in the normal gravity of earth?

 

[RU482]

haven't read any of the posts....saw the headline and thought "how long can people that weigh 3x what I weigh stand"?

probably not long

 

[CLite]

I'm figuring that if a craft left Earth orbit with an acceleration of three times that of gravity so that the craft's occupants would be crashed then how fast would they get at the mid-point of any journey in order to do a 180º ship-flip to slow down at the same rate. Let's assume the destination is local, like Pluto and we are just traversing the approximate planet-Sun radius (3.6 Billion for Pluto and 0.093 Billion for Earth).

This ouwl mean an radially-outward travel is roughly 3.5 Billion miles. Simple math, but the time is still long vs. the gravity getting unbearable for long-term exposure.

That is not close to necessary. If you could maintain 1.5g you would get to Pluto in 7 days, reaching a maximum velocity of 4,535,467 m/s at the midpoint on day 3.5 which is lubriciously fast (1.5% the speed of light and an order of magnitude faster than Voyager).

time = (D/a)^0.5 = (5.7*10^11 / g)^0.5 seconds

You can play with different g-levels, even an acceleration of 1g will get you there in 8.73 days.

 

[wuliheron]

Its not just the added weight, but what parts of the body can take the extra stress. We've evolved to deal with weight increases, but not increases in gravitational forces that can affect everything from your retinas to the individual cell walls. Even the Air Force doesn't have long term studies of increased gravitational/acceleration forces applied nonstop for months on end. About all anybody can say is it will have side effects including quite likely some serious health hazards.

At relativistic speeds the vacuum of space can be like hitting a radioactive brick wall with the force of an atomic bomb. Charles Sheffield, physicist and science fiction author, proposed using a large disk of condensed matter in front of a spaceship to counter the worst of the effects of high acceleration and use as an ablative shield. As you accelerate you move your life capsule closer to the disk and its gravitational pull counters the acceleration. There are still strong tidal effects, but the worst problems are eliminated. As for fuel, such a craft could be powered by a solar satellite that remains stationary around the sun or even a series of them at increasing distances from the sun that relay power to the ship.

 

[MrTeal]

That is not close to necessary. If you could maintain 1.5g you would get to Pluto in 7 days, reaching a maximum velocity of 4,535,467 m/s at the midpoint on day 3.5 which is lubriciously fast (1.5% the speed of light and an order of magnitude faster than Voyager).

time = (D/a)^0.5 = (5.7*10^11 / g)^0.5 seconds

You can play with different g-levels, even an acceleration of 1g will get you there in 8.73 days.

This.

Also, constant acceleration requires exponentially increasing power. Under 3g of acceleration, a 1000kg spacecraft that goes from 100m/s to 130m/s requires ~3.5MJ of energy and an average of ~3.5MW of power (just imparted into kinetic energy). After an hour when you're traveling ~35km/s, going from 35,316m/s to 35,346m/s requires ~1GJ of energy. After a day when you're at ~850km/s (more than the escape velocity of the galaxy) you're now needing to impart 25.4GW of kinetic power to maintain 3G acceleration.
This obviously ignores relativistic effects which are still fairly small at the speeds I mentioned, and the effect of climbing out of a gravity well, but even this simple example shows how maintaining 3Gs for even a day would really be impossible with even currently conceivable power sources.

Edit: Exponentially increasing power WRT velocity. Power would increase linearly WRT time. Also, didn't notice the original thread was from 2006. Oops.

 

[SpatiallyAware]

Could a gyroscope be setup to spin in such a way as to offset the downward effects of the 3g?

 

[kevinsbane]

Could a gyroscope be setup to spin in such a way as to offset the downward effects of the 3g?

No, as any kind of centripetal acceleration (a la centrifuge induced constant acceleration) has a constantly shifting vector, and thus would be useless as far as reducing apparent weight.

If you could somehow manufacture a hyperdense material which would induce a 4G acceleration using gravity, and then move this object ahead of you at a 3G acceleration, you could achieve a net 1G apparent weight. That, of course, ignores tidal forces, which would likely be extreme if the mass is relatively small (ie, less than that of a small asteroid). Some sci fi story made use of this technique... I forgot which one.

 

[SpatiallyAware]

No, as any kind of centripetal acceleration (a la centrifuge induced constant acceleration) has a constantly shifting vector, and thus would be useless as far as reducing apparent weight.

If you could somehow manufacture a hyperdense material which would induce a 4G acceleration using gravity, and then move this object ahead of you at a 3G acceleration, you could achieve a net 1G apparent weight. That, of course, ignores tidal forces, which would likely be extreme if the mass is relatively small (ie, less than that of a small asteroid). Some sci fi story made use of this technique... I forgot which one.

Ah good point.. dunno what I was thinking, really.

 

[GWestphal]

Well based on my research of subjects Goku and Vegeta, your hair would turn blonde and spiky and your eyes would turn turquoise. You might begin to emit lightning as well. Additionally, your power level would be far over 9000.

Lets say if somebody made a machine that could crate gravity in in one room at any level from 1 to 100 times earth gravity. Could if somebody trained in there for long periods of time and what I mean by training is do there normal routine but in higher levels of gravity even work out. could they get used to higher levels of gravity over time and possibly even move in there freely as they do in the normal gravity of earth?

 

[piasabird]

There is a difference between 3 times the gravity and 3 times the atmosphere. External pressure on the body at 3 atmospheres could be withstood with a form fitting suit like a divers suit. However, gravity would put a lot more stress on your muscles and your skeletal structure. Bone density can withstand just so much punishing. It might be possible to compensate quite a bit if it was a gradual change. Try picking something up 3 times the weight and walking around with it. It would be like weighing 450 lbs.

You might study boyles laws of atmospheres. 3X gravity would depress the atmosphere Making the atmosphere have less volume.

 

[PsiStar]

Maybe more fundamental is the rate of change? Can the human body adapt to 3X gravity over a period of time? Could a dog? Could a cat? Could green eggs & ham? Sorry, something weird inside me made ask that last one.

I think with time that most life on earth, the life as we know it, could adapt to 3X gravity. For animal life this would result in denser bones, stronger hearts, & stronger muscles in general. I jump to this rationalization because of the opposite effect of extended life in space for astro/cosmo -nauts.

Then, maybe, the even grander question, at what gravity level could life as we know it, not be able to adapt regardless of the rate of change?

 

[pw38]

Maybe more fundamental is the rate of change? Can the human body adapt to 3X gravity over a period of time? Could a dog? Could a cat? Could green eggs & ham? Sorry, something weird inside me made ask that last one.

I think with time that most life on earth, the life as we know it, could adapt to 3X gravity. For animal life this would result in denser bones, stronger hearts, & stronger muscles in general. I jump to this rationalization because of the opposite effect of extended life in space for astro/cosmo -nauts.

Then, maybe, the even grander question, at what gravity level could life as we know it, not be able to adapt regardless of the rate of change?

Sure animals could adapt. They either do or they die. There's really no other way. Larry Niven had a good example of this with his Known Space Universe. The humans of 'Jinx' adapted to the oblate nature of their moon by essentially becoming dwarves. It's a pretty interesting thought experiment although I doubt they'd adapt as quickly as the books seem to suggest. Who knows though when presented with extreme circumstances maybe life adapts in extreme ways. We see it here on Earth so who's to say?

As far as what gravity life wouldn't be able to adapt well that's a good question. Obviously a neutron star level of gravity would be a bad place to start but who knows, what type of life are we talking about? I'm thinking it would be much easier for microorganisms to survive in such harsh conditions versus complex multi-cellular life.

 

[Matchstckgmr]

Thats funny "Well based on my research of subjects Goku and Vegeta, your hair would turn blonde and spiky and your eyes would turn turquoise. You might begin to emit lightning as well. Additionally, your power level would be far over 9000." Yes I got the idea from dragon ball z but it was a serious question none the less I wanted to know if a person could get stronger, survive, and adapt to higher levels of gravity. Granted I know anime is a cartoon and as such like most cartoons regardless of what country they come from you can't always do what you see in one but it got me thinking on if a person did make a room that could make fake gravity and turn it up to higher levels could a person really get used to it and get strong and walk around in higher levels of gravity much like one would in normal gravity.

 

[CycloWizard]

The amount of wild speculation and misinformation in this necro-thread is really disturbing. Perhaps in a highly technical forum, people should state when they are speculating rather stating the ridiculous as facts. Some work has been done on bone adaptation and remodeling in response to cyclic strains, though this work is limited in scope. Some of the findings have even been applied to space travel. Coincidentally, I'm giving a lecture on the topic today, but for those of you not in Texas, I'll simply point you directly to the work of Carter and Beaupre.

 

[JTsyo]

That is not close to necessary. If you could maintain 1.5g you would get to Pluto in 7 days, reaching a maximum velocity of 4,535,467 m/s at the midpoint on day 3.5 which is lubriciously fast (1.5% the speed of light and an order of magnitude faster than Voyager).

time = (D/a)^0.5 = (5.7*10^11 / g)^0.5 seconds

You can play with different g-levels, even an acceleration of 1g will get you there in 8.73 days.

this constant acceleration really adds up fast. That's while things like solar sails makes sense for long trips. Though they only work in one direction.

 

[donghui90]

goku

 

[CLite]

this constant acceleration really adds up fast. That's while things like solar sails makes sense for long trips. Though they only work in one direction.

Like the sailing orientation of "running before the wind", you are limited by the speed of the tailwind. A solar sail would have an acceleration curve that approaches zero as the speed of the craft increases. Also what allows a sailboat to go directions other than away from wind is the rudder and resistance from the water. I can't really conceive how a solar sail craft would navigate the relatively complex flight paths within the solar system without having a lot of help from conventional rockets.

 

[Pinecone-sw]

BTW modern fighter aircraft can generate 9G.

A lot has to do with the direction of the G force. If you are lying down, it is easy. Standing up, not so easy. That is why the seat in the F-16 is tilted back 30 degrees.

Also, a pressure of 3 atmospheres is nothing. Like diving to 66 feet. No form fitting suit needed. Saturation divers live for weeks at very high pressures. The record is 534 m = 54 atmospheres of pressure. The body takes pressure well.

On science fiction writer had people doing this type of constant acceleration flights. He had the people laying on couches, with support, and occasionaly periods of low G to attend to bodily functions.

Standing up at 3G is like squat pressing twice your body wieght. How many people can do that?

 

[Howard]

Standing up at 3G is like squat pressing twice your body wieght. How many people can do that?

"Squat pressing" isn't standing.

 

[Matthiasa]

Maybe more like a leg press in terms of what the legs would feel in which case nearly anyone can, for short periods.