Science a GoGo's Home Page Forums General Discussion General Science Discussion Forum Speed of light travel

Taking into account the effects of G-Force on the human body. And assuming that light speed travel could be attained.

What is the shortest total distance that a Human could accelerate to the speed of light, then decelerate back to a standstlill and be expected to survive the trip?

Greatings Y

You need to update your knowledge base. Check these urls:

http://math.ucr.edu/home/baez/physics/Relativity/SR/rocket.html

http://en.wikipedia.org/wiki/Relativistic_rocket

http://www.rzg.mpg.de/~bds/space/rocket.html

More specific to your question - have a look at the applet on this site:

http://ucsu.colorado.edu/~obrian/applets/Rocket/Voyage.html

Hope that helps,

Dr. R.

Accelerating to within an arbitary epsilon of lightspeed is trivially accomplished - fall directly into a large radius black hole event horizon. Small radii give personal quadrupole tidal disruption problems re the Roche limit. Compensate your trajectory for Lense-Thirring frame dragging (Kerr-Newman black holes). Putting on the brakes is left as an exercise for the alert reader.

NASA centrifuge studies demonstrated that even 2 gees sustained chews up humans. Remember to wear your athletic supporter.

In the future humans will be able to travel at lightspeed. Within a few hundred years humans will have replaced their biological bodies with machines. Their brains will be digital.

Digital people can upload their brains from one machine to another via radio and can thus effectively travel at lightspeed.

In the future humans will be stuck on this planet wallowing in their stupidity while their machines explore the galaxy.

Today we can't even do what we did in the 1970s: Put a man on the moon.

The idea that "Today we can't even do what we did in the 1970s: Put a man on the moon." expresses an unrealistic concept of exploration and our technological capabilities.

Think about the European exploration of North America for a moment. (Forget Pacific intercostal migrations.) The Vikings set sail for new places (colonization/trade/conquest?) about 1000 AD. As we all know Columbus sailed the ocean blue in 1492. In 1524, or so, Verrazzano explored the North American coast from Florida to Newfoundland. This was followed by slow but steady colonization by the Spanish, English, etc. This did not have much effect on the European population until the 17th century when whole towns would find themselves without people. The history is very complicated and I am not a historian. However, it is clear that the exploration and exploitation of new areas procedes in time frames measured in decades and centuries. There is no orderly program - there is no one at the head of the parade with a baton. There is, in fact, a complex web of human passions and motivations. It moves by fits and starts at first and then, when the time is right it gushes like a fire hose.

It seems to me that the exploration of space is progressing about as fast as any other exploration.

As for the ability to go to the moon - we actually do have the capability, it is just not being used right now. I would argue that we are currently more capable of lunar excursions as there has been decades of technological development since the last moon landings.

Why would any European leave their home for the New World. Except for a few it would not be for any grand adventure or noble desire to explore. The tax man and the bishop are what motivates. What would motivate the modern individual to leave the planet? Religous oppression, crowding, diseases, the price of gas - who knows.

In the mean time spitting sour grapes because expectations generated by 1960s NASA media hyperbole didn't work out is futile.

A brilliant Nazi and a bunch of gung-ho engineers with slipsticks - working from scratch - vastly outperformed the resultant multi-$billion bureaucracy wielding the largest most sophisticated computers on the planet - and that already knew a working answer.

Stupid without a computer is still stupid with a computer. There is no triumph of mind or labor that cannot be destroyed by professional management.

Special Relativity (SR) is a self-consistent geometry. It cannot be fooled, cheated, embezzled, excommunicated, politically redirected, or otherwise avoided. No human-scale mass can be given a relativistic velocity, by the book.

One then needs better, more inclusive physics in which SR is a restricted subset subject to disjoint finesse. The only predictive and testable physical theories that tolerate such are Cartan's teleparallel spacetime, Weitzenb?ck's affine spacetime, and string theory's heterotic component.

Somebody should look. All three predict that local left and right hands do not vacuum freefall identically (parity summetry breaking of the Equivalence Principle). Uncoupling inertial and gravitational mass can finess SR because it operates outside one of SR's founding postulates. Then, zoom zoom.

the technology to build a Saturn type rocket still exist, as does the ability to use it. the question is why use it. there are better ways of doing it.

it would have been possible, though unlikely for european to use a canoe type boat to reach the new world. how many ppl do you think would have reached it. the early sail boats would not have survived the Atlantic, while later sail boats could circle the world.

in case you are not aware, Columbus was not the first person to cross the Atlantic. the vikings did that long before he did. there is even evidence, though not much or even fully accepted, that others reach the shores before them, usually, according to storied, blown there by storms. did these result in colonization? no. why? because the ships used were not capable of crossing the Atlantic with any degree of safety (meaning lots of loss of life, who would risk that), or cross more than a few times (ships were expensive, why would ship owners risk them). By the time of Columbus, ships had improved to the point that the safety was vastly increased, and the ability to return often enough to be worth the cost was increased.

Saturn v was like the early ships, capable of getting there if they were done just right, but not duplicated able, and way to expensive, and dangerous, to allow colonizing. technology is advancing enough and fast enough, that we might soon be able to colonizing the moon, space, and mars. perhaps soon our children will even be able to reach the stars

Unfortunately the dirty little secret is that
if you put a man into space for any length of
time, he's unlikely to be able to breed true.

So much for colonization until we can boost
the heavy shielding required.

Pragmatist

actually no. we dont need to boost it. theres plenty there, if we learn to use it. they have found that the lunar soil is a great shield. im afraid i forgot how many feet it would take, but boosting it from the moon would be so easy compaired to boosting it from the earth. when we can learn to capture asteroids, it will be even easier.

dehammer,
You forget its still got to be 'boosted` onto
the orbit for the trip.
Actually, you could use water, (also usefull
as reaction mass for decelleration with some
drive systems, or drinking, or needed when you
finally arrive), but you've still got to push a heluva lot more mass on a manned trip and that either costs energy or slows you down a lot.
We're probably stuck with robot probes for the
near term.

Pragmatist

why do you have to boost an object into space that is already there.

nasa has plans they hope to realise, that involve using an electomagnetic rail on the moon to "boost" a rail cart carrying a payload to a specific speed, then release it. the cart would then decelerate along the same rail, while the payload would continue to move along the same trajectory. once it was high enough it could use several methods to alter its course (including solar sails) to take it to the desired destinations.

the same sails could be used to alter the course of near earth objects, enabling them to become captured by the earth's gravite with no or little risk of hitting the earth. with gravity in the micro range, most of these would enable ppl to mined them, meaning little or no matterial would have to be boosted from the earth. only the energy to change orbits would be required. some of that could come from the asteroid or the sun.

once the ship was ready to go, it would be possible to alter its course with solar energy.

i forget where i saw it, but there was one suggestion that it we should not actually build a star ship before we launch it. the reason, if we use solar sails or something like it, plus gravity slings (simular to the way the saturn probe that recently arrived there was sent) it would take close to a decade to get the ship fast enough to leave the solar system. during this time, it would pass near the earth several times.

this proposal involved sending a small probe to a moderate size near earth asteroid, with a solar sail. a ship would be built near the earth at the same time, a bit larger than a 747 with a solar sail propulsion system. when the object was closeing on the earth, the shuttle would begin making several trips between the earth and moon, using their gravity to boost the speed up to where the shuttle could catch the asteroid. once they had caught it, they would stablize it into a spin, then they would begin to mine a living area. once it was capable of surviveing on its own, they would send the much lighter ship back to the earth. this would continue for sometime as they made the ship more liveable. just before it became fast enough to leave the system, the shuttles would make a last trip with the last of the ship crew.

ive not been able to find this on the net, and even then questioned his math, but according to this theory, it would be possible to send a ship to another star that would reach about half light speed this way. he also claimed that in 1970's dollars it would be cheaper to build and send this ship than the space program cost to send a man to the moon.

unfortuantely, your right about the near term.