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CL8
2004-Mar-28, 06:40 AM
Can we create Artifial Gravity ? no not yet anyway

We got Cent pedy force yeah but thats bulky we need to think of a way attact mass in floor panneling

I going to go absurd for a sec cause I can
What if a metal like lead was circulated threw a polarized semi permuable membrane that would remove the elctrons on a down pass form the metal creating a instablity in the gravity well of the universe creating a pull the elctrons a recombined on the up pass the elctrons recombine with the metal restabilising the metal

whta you think peeps

Phobos
2004-Mar-28, 10:50 AM
Yes very easily - But at a price.

The problem is we need continuous thrust to provide accelaration at 1G, and that requires a lot of energy. If we were able to provide the accelaration for half of a space journey in a spacecraft, then turn it through 180 degrees, then our engines would produce decellaration at !G too.

The net result is that our spacecraft would have a force of gravity inside that would be indestinguishable from gravity on Earth.

Unlike spinning spacestations etc the gravity would be "Normal", you could look out of a window and not get dizzy seeing the stars spinniing, and the effect would be totally convincing.

Whilst it would require a large amount of energy, you would also benifit from reducing your journey time. Should you be able to sustain this accelaration for a year you would also find yourself aproaching light speed.

countrywideoptionone
2004-Mar-30, 06:48 PM
Yes..Should you be able to sustain this accelaration for a year you would also find yourself aproaching light speed.
Nice answer. What happens during the second year, as you get closer and closer to light speed?

CL8
2004-Mar-30, 08:35 PM
I considered the thrust issue but
I want the gravity to be usable at a stand or still too

mike alexander
2004-Mar-31, 12:32 AM
What happens during the second year, as you get closer and closer to light speed?

You get closer and closer to light speed.

countrywideoptionone
2004-Mar-31, 09:45 PM
What happens during the second year, as you get closer and closer to light speed?

You get closer and closer to light speed.

Okay, I'll be a little more specific. If your initial rate of acceleration is say 9.8 m/s/s, what happens to the rate as you approach c? I'm assuming you don't just stop accelerating when your speed equals c - (some very small number>0)

informant
2004-Apr-01, 12:22 PM
If your initial rate of acceleration is say 9.8 m/s/s, what happens to the rate as you approach c? I'm assuming you don't just stop accelerating when your speed equals c - (some very small number>0)
"Very clever, young man, but it's turtles all the way down." :D
[now seriously]Your speed never does equal c.[/now seriously]

Tirdun
2004-Apr-01, 03:36 PM
The amount of energy required to continue the acceleration approaches infinity. The question becomes academic once you can no longer produce enough force to push yourself forward faster.

The trick might be to reverse the position of the living area and then decelerate at 9.8m/s/s ;)

tofu
2004-Apr-01, 04:12 PM
What if a metal like lead was circulated threw a polarized semi permuable (snip)
huh?



If your initial rate of acceleration is say 9.8 m/s/s, what happens to the rate as you approach c? I'm assuming you don't just stop accelerating when your speed equals c - (some very small number>0)
Here's my understanding of it: If you are inside the spaceship measuring the acceleration with an accelerometer, you would see 9.8 m/s/s forever. At least as long as the fuel holds out. If the engines can run for a year or a decade or a century, you would observe 9.8 m/s/s the whole time.

If you are outside the spaceship and somehow accurately measuring its acceleration, you would see the acceleration decreasing. It would appear lower than 9.8 and would approach, but never reach, zero.

The difference is time. On the spaceship time would slow down. If you had a live video feed to the spaceship, you might tell them that it looks like they aren't accelerating at 1G. When they respond, they will tell you that they feel 1G (thank you very much) but from your point of view, they would be speaking more and more slowly. Also, if you looked at the spaceship through a telescope it would appear curiously shorter.

I think what you were really asking was, what actually keeps a spaceship from going faster than c. I think you were asking who enforces the universal speed limit. The answer is time dialation.

countrywideoptionone
2004-Apr-01, 04:45 PM
...The answer is time dialation.

Thanks! Nice answer. One more question. When you say, "outside the spaceship and somehow accurately measuring its acceleration," do you mean the observer is or is not accelerating is a similar manner as the spaceship (ex. one of the crew member puts on a space suit and goes outside the ship for whatever reason, then returns inside vs. someone on Earth watching with an extraordinarily powerful telescope)?

Okay, one more question again. The observer from Earth sees the ship as curiously shorter, what happens if the ship remains on its course, but turns slowly to the right 90 degrees, letís say over the course of 24 hours (approximately). As the ship approached the 90 degree mark, wouldn't its length return to normal and its width "get skinny?" Also, wouldn't the crew experience this same shortening/returning to normal, as they turned? Or is this effect only noticeable from a difference reference frame, like Earth's?

Okay, you got me, one more question. In the live video feed it appears they are moving/speaking more slowly than we are (on Earth). From their point of view, wouldn't we appear to be moving/speaking more quickly? And if two crew member video conference each other from two different place on the ship, wouldn't they appear normal to each other?

tofu
2004-Apr-01, 05:19 PM
When you say, "outside the spaceship
Normally, the question is stated as "a spaceship leaves Earth" etc. So that's what I was assuming, an observer on Earth looking at a ship traveling away from Earth. I have to be careful because this website is crawling with people who understand this a lot better than me and I've probably already said something incorrect.


As the ship approached the 90 degree mark, wouldn't its length return to normal and its width "get skinny?"
Yes. That's the way I understand it.


Also, wouldn't the crew experience this same shortening/returning to normal, as they turned?
No. The point of relativity is that you don't feel any of the effects. You observe an effect as happening to someone else, but if you interview them, they will say that they don't feel it. That's why people say "it's all relative." I look at you and see a change. But you look at yourself and don't see that change. On the contrary, you look at me and claim that I'm undergoing the change.

That's why the people on the spaceship will feel 9.8 m/s/s forever and ever. In their frame of reference, the engines are working just fine and they are happily accelerating. But someone outside their frame of reference observes something totally different. They see the rate of acceleration as slowing.

And both observers are absolutely correct. It's all relative.


From their point of view, wouldn't we appear to be moving/speaking more quickly?
Uh oh. I don't know the answer to this one. Intuitively, I think that both parties will see the other as slowing down. Imagine the radio wave that's carrying the television signal. Imagine the little ones and zeros zipping by the antenna on your spaceship. You are nearly outrunning the signal, so the ones and zeros are passing by more slowly.

And here's why I have to admit that I don't know the answer and hope someone else can correct me. You will always measure the speed of light as c. Even if you are heading away from the source at close to c, and even if the source is heading away from you at close to c. What happens is that the light, instead of appearing to slow down, appears to get longer in wavelength. So the radio wave is still zipping by your antenna at c, but the wavelength is longer so it takes more time for each 1 or 0 to go by.

Whoa, I'd better stop now, I'm out of my league!