Majestyk

Whether it is 1g or less, it needs to be sufficient to prevent the loss of bone mass that has been experienced in extended exposure to microgravity enviroments.

Magus55

Thanks for showing, we can't have a civil conversation without someone putting in their half witted sarcasm when i was just trying to talk about something interesting.

Magus55

I meant, travel, in a space ship to say Alpha Centauri. Thanks Jesse, wasn't aware that you could travel extremely fast without a gravity problem, as long as you accelerate slow. Would it take a along time to reach those speeds though if accelerating slow enough to maintain 1 G?

I did some caculations, and found travelling at 50,000,000 miles per hour would take about 50 years to reach Alpha Centauri. I just always thought travelling at those speeds would disintegrate a ship, not even counting the kind of massive energy and engine it would take to reach those speeds.

Infidelettante

Now did you really think Magus55 that this would stay clear of religion?

Here's how to connect space travel and the Garden of Eden. Adam and Eve are symbolic of humanity. We gained the ability to choose our own path, apart from God or with him, in Eden. This made us god like in some sense. Or so says the Bible.

Recall that Adam and Eve were banished from the garden so they could not attain eternal life, not because they disobeyed God. Gods greatest fear is that humans will one day find eternal life and challenge him for control of Creation. When that day comes humanity will chart it's own path apart from God who could never hope to compete with his creations creativity and drive. We will be, after all Gods when we can live forever. Or so the Bible says.

When will humanity attain eternal life? When we leave this planet for the stars! We can not survive on one planet. The day will come when the next comet hits or when too many volcanos erupt. We must own the stars if humanity is to live forever. Then we will have no need of God for we will have gone beyond him.

It may take a very, very long time and I would love to see the look on his face when the humans take over.

JT

Asha'man

Yes, there would be a massive energy requirement to reach that speed, but once you get there, it's just coasting. Inertia would keep you going quite nicely.

Remember, space is a hard vacuum. It's empty, very empty. Unlike a car or airplane, there is no ground or air friction to deal with, so you can go really fast without much problem.

However, having said that, space is not a perfect vacuum. There is interstellar dust and gas, it’s just very thin. (Something on the order of a single atom per cubic meter.) The front of your ship would need to have some sort of shielding, to protect the occupants from the high-speed impacts with particles of interstellar matter.

Jesse

Magus55:
Thanks Jesse, wasn't aware that you could travel extremely fast without a gravity problem, as long as you accelerate slow. Would it take a along time to reach those speeds though if accelerating slow enough to maintain 1 G?

No, as I mentioned in my first post, if you accelerated at 1 G for the first half of your trip and decelerated at 1 G for the second half, you'd reach the nearest star (4.3 light years away) in 3.6 years of subjective time, and the andromeda galaxy (2 million light years away) in 29 years of subjective time. However, the time as seen from earth would be slightly larger for the nearest star, and millions of years for the Andromeda Galaxy.

Magus55:
I did some caculations, and found travelling at 50,000,000 miles per hour would take 45 years to reach Alpha Centauri.

50 million mph is 4.38 * 10^11 miles per year, and a light year is 5.86 * 10^12 miles, so I get 57.5 years for the time to go 4.3 light years, but maybe the difference is just roundoff error. This would be the time as seen from earth, but because of relativity the onboard time would be slightly smaller, although not by much--50 million mph is about 0.075 light speed, so plugging this in for (v/c) and 57.5 years for T into the relativistic time dilation formula:



gives 57.5 = T0/(0.997) --> T0 = 57.3 years of onboard time, a pretty minor difference. But if you're going a much larger fraction of light speed, the relativistic time dilation can become more significant.

Magus55:
I just always thought travelling at those speeds would disintegrate a ship

No, in both Newtonian and relativistic physics speed is all relative, there is no physical way to measure "absolute velocity." If your velocity relative to me is 50 million miles an hour, one can use a reference frame where I am at rest and you are travelling at 50 million mph, but one can equally well use a reference frame where you are at rest and I am travelling 50 million mph in the opposite direction, or a reference frame where we are both travelling 25 million mph in opposite directions. All theories of physics that are used today say that physics works the same in all "inertial reference frames", ie any reference frame that is not accelerating and experiences no G-forces. If I'm in a windowless ship travelling at a constant velocity, this means there's no known physical experiment I can do in the ship that will tell me whether I'm at rest relative to a given reference frame (say, the reference frame in which the galaxy is at rest) or whether I'm travelling at some incredible velocity relative to that frame. On the other hand, if I'm accelerating, I will be able to tell this even if I have no windows to view the outside world, because I'll feel G-forces.

Magus55:
not even counting the kind of massive energy and engine it would take to reach those speeds.

Yes, that's the real obstacle to interstellar travel, the energy you'd need to accelerate to a sizeable fraction of light speed. Also, if you carry the fuel with you (as opposed to solutions like being pushed by a laser or using a 'bussard ramscoop' to pull in interstellar hydrogen) then you have the problem that the more fuel you carry, the more massive the ship, and the more massive the ship, the more total fuel is needed to accelerate it to a certain speed. This is why rockets come in stages that are discarded as you go, and it's also why on an interstellar voyage you'd want a reaction that releases as much energy as possible for a given mass of fuel, like nuclear fusion or matter/antimatter annihilation.

Wounded King

I certainly hope we make it out of thesolar system, if we don't the only way I think things will go is downhill.

Jost to re-use my favourite hobby-horse. Exotic matter used to construct regions of negative energy, such as the field observed in the Casimir effect, always sounded good to me.

The real problem is getting people motivated, the way things are going no one is even going to get to mars until this planet is turning to shit around them, except perhaps the chinese. Why would countries want to spend money devloping space ships capable of sustaining life for 4 years, at a conservative estimate, when they could be building an even bigger bomb.

You realise what this all means of course, Bill Gates and Ronald McDonald are going to be sponsoring the colonisation of the universe, I wonder if there is another universe I could opt into.

Demigawd

I agree with Magus about this. There are some good responses to his question here. Let's not derail this discussion with snide comments. Save those for actual religious discussions.

*points to self as being guilty of that*

Arbogast

That people in the future will leave the earth (that is with the assumption, of course, that there are no local alien civilizations that will limit our interstellar migration).

It just seems a human thing to do.

It seems to me a very simple method(with slightly more advanced technology than we have), would be to store humans as embryos, leave them with computers with a huge library, and when they get near the destination, have them grown and raised by robots and computers.

At least, that seems a very economical solution.

Undercurrent

The way to ameliorate this, without resorting to using external components in your propultion system, is to make the nozzle velocity extremely high, so you get the biggest delta-v per unit fuel.

Ion rockets, which, as proposed, would use very little propellant per unit time, but eject it out the nozzle at very high speeds would be most effeicient in that regard.