Something I haven't seen mentioned yet is how we, as organisms, would cope with the acceleration required for even, say, 0.5C velocities.

We would obviously want to reach the cruising velocity in a faily short space of time, but without being reduced to soup on the rear bulkhead.....

I feel this is an even more important point than the possibility of super-light speed travel, as it has immediate implications as even our current 'fireworks' put us at pretty much the limit of human endurance, G-wise.

Well, I'm pretty sure that by the time we figure out how to travel at (or faster than) the speed of light, we'll also know how to deal with intense accelerations. ;)

Although, I wouldn't mind spending one entire month accelerating to reach the speed of light. It's worth it.

/Regards.

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/Mav

We have lingered long enough on the shores of the cosmic ocean.
We are ready at last to set sail for the stars.
(Carl Sagan)

Yep, I've just done some quick and rough calculations, and it would take around 20 days to reach 0.5C at 10G acceleration, which as you said, isn't too bad.

Is that right though??
Just seems a bit too short a time to attain such a high velocity......

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Yep, I've just done some quick and rough calculations, and it would take around 20 days to reach 0.5C at 10G acceleration, which as you said, isn't too bad.

Is that right though??
Just seems a bit too short a time to attain such a high velocity......

I've done no calculations, but from what I've read, constant acceleration in a (near) frictionless environment adds up very quickly.

As just a guess, I would say your calculations are pretty close.

Although, 10g's for 20 days (edit: without some sort of inertial dampening) would probably kill a human being. What would it take at 2 g's?

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Calm Chaos Forum...Join Calm Chaos Now

100 days at 2G - it's a linear relationship.

The trouble really is that even if we could attain 0.5C at survivable accelerations, which it now seems we can in theory, it would still take over 8 years to reach the closest star system - a heck of a lot longer for most others!

I don't like to sound negative, but we have a major obstacle ahead of us if intergalactic travel is ever going to happen.

I think we are looking at velocities in excess of 1000C in order to shrink the 'local neighbourhood' down to managable size, and then acceleration issues really do raise their ugly heads.

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The relationship between acceleration and final velocity is only linear when the acceleration is measured in the same frame as the speed. However, if the issue being considered is the effect of acceleration on travellers, the relevant acceleration is that measured in a frame instantaneously comoving with the spaceship. In other words, we want the acceleration to be constant when measured by the travellers, not by observers on Earth.

In this case, the relationship between velocity, acceleration, and time is:

v = at/sqrt(1 + (at/c)^2)

instead of v = at.

If you check, you'll find that the upper formula has a speed limit of c, while the lower does not (at least not explicitly).

The distance travelled in a given time will be:

x = (c^2/a)(sqrt(1 + (at/c)^2) - 1)

The other important piece of information needed is the amount of time experienced by the travellers which will not be the same as the time that passes on Earth while the ship is in transit. This time is given by:

T = (c/a) sinh^(-1) (at/c)

Just for fun, you might want to check how far you could get in a given time with a 1g acceleration and see how long the time experienced by the travellers is.

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Solomon, you are obviously far more familiar with these formulae than I am, plus I'm a bit tired tonight!!
(Plus I'm a bit thick)

Could you do us the honours, just for a bit of fun? Or anyone else who fancies a go.

Scenario:
Let's say our travellers set off from Earth accelerating at a constant 1G - the caraft's maximum and only acceleration.
As measured on board ship, they travelled for 200 days accelerating constantly, then started to accelerate back towards Earth - a total of 400 days (presumably) before they actually change direction.

Allowing for the time needed to finally decelerate in order for a safe landing on Earth to be accomplished, I'm assuming a total of 800 days would have elapsed as measured by their onboard clock, (assuming hypothetically that the Earth hadn't changed position) but how much time would have elapsed on earth as measured by earthbound observers?

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Well, you've described a sort of trip with four legs; but, we can figure out the answer by using only one of the four. The reason we can do this is that the relationship between T and t is unchanged if I replace a by -a. So, let's look only at the first leg, with acceleration 1g.

We can invert the formula I gave for T to get t, the time that passes on Earth.

t = (c/a) sinh(aT/c)

c = 2.998*10^8 m/s
a = 9.8 m/s^2
T = 200 days = 1.728*10^7 s

So, the elapsed time on Earth during the first leg of the trip will be 1.82*10^7 s, or about 211 days. Multiplying by 4 gives a round trip time of 843 days that pass on earth.

We can find the ship's top speed and distance travelled by using the other formulas I cited, now that we know t.

The ship will be moving fastest just before it switches its acceleration on day 200 (or 210 as seen on Earth). So, its top speed will be:

v = 1.53*10^8 m/s

The ship will reach 51.1% of the speed of light.

At the point when the ship has reached this velocity, it will have travelled a distance:

x = 1.50*10^15 m

The maximum distance the ship reaches (the point when its velocity is 0) will be twice this:

x_max = 3.00*10^15 m

This is almost 1/3 of a light year; so, this ship would get 1/12 of the way to the nearest star. To put it a different way, this is more than 500 times the distance to Pluto.

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I'm going to go out on a limb here, and risk being bashed and burned at the stake.

Am I the only one that thinks the gravitational and velocity dilation of time is a crock of bull-dreg?

Gravity may curve light, yes, but time dilation caused by gravity or speed is an illusion. ;)

At least in my opinion of course.
Come on, somebody back me up.

/Regards

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/Mav

We have lingered long enough on the shores of the cosmic ocean.
We are ready at last to set sail for the stars.
(Carl Sagan)

Double post. :(

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/Mav

We have lingered long enough on the shores of the cosmic ocean.
We are ready at last to set sail for the stars.
(Carl Sagan)

I'm going to go out on a limb here, and risk being bashed and burned at the stake.

Am I the only one that thinks the gravitational and velocity dilation of time is a crock of bull-dreg?

Gravity may curve light, yes, but time dilation caused by gravity or speed is an illusion. ;)

At least in my opinion of course.
Come on, somebody back me up.

/Regards

You're going to have some trouble backing that up, since both effects have been directly observed.

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I'm going to go out on a limb here, and risk being bashed and burned at the stake.

Am I the only one that thinks the gravitational and velocity dilation of time is a crock of bull-dreg?

Gravity may curve light, yes, but time dilation caused by gravity or speed is an illusion. ;)

At least in my opinion of course.
Come on, somebody back me up.

/Regards

LOL. I personally don't believe in time so I'm not to concerned about it being dilated.

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TEAM
LL

I'm inclined to agree with Diego. Its rubbish. Its science gone mad.

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I'm going to go out on a limb here, and risk being bashed and burned at the stake.

Am I the only one that thinks the gravitational and velocity dilation of time is a crock of bull-dreg?

Gravity may curve light, yes, but time dilation caused by gravity or speed is an illusion. ;)

At least in my opinion of course.
Come on, somebody back me up.

/Regards

You're going to have some trouble backing that up, since both effects have been directly observed.

Heh, well yes, you can directly observe an illusion. Like in a magician's act.
In any case, maybe what is affected is the intrument used to measure time, not "time" itself.

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/Mav

We have lingered long enough on the shores of the cosmic ocean.
We are ready at last to set sail for the stars.
(Carl Sagan)

LOL. I personally don't believe in time so I'm not to concerned about it being dilated.

You must really be always late, then.
Girls must love you. :p

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/Mav

We have lingered long enough on the shores of the cosmic ocean.
We are ready at last to set sail for the stars.
(Carl Sagan)

LOL. I personally don't believe in time so I'm not to concerned about it being dilated.

You must really be always late, then.
Girls must love you. :p

I beleive in using a tool created by man to sync my events with the events of others.

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TEAM
LL

LOL. I personally don't believe in time so I'm not to concerned about it being dilated.

You must really be always late, then.
Girls must love you. :p

I beleive in using a tool created by man to sync my events with the events of others.

Now we are talking. ;)

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/Mav

We have lingered long enough on the shores of the cosmic ocean.
We are ready at last to set sail for the stars.
(Carl Sagan)

I'm going to go out on a limb here, and risk being bashed and burned at the stake.

Am I the only one that thinks the gravitational and velocity dilation of time is a crock of bull-dreg?

Gravity may curve light, yes, but time dilation caused by gravity or speed is an illusion. ;)

At least in my opinion of course.
Come on, somebody back me up.

/Regards

You're going to have some trouble backing that up, since both effects have been directly observed.

Heh, well yes, you can directly observe an illusion. Like in a magician's act.
In any case, maybe what is affected is the intrument used to measure time, not "time" itself.

So, how about we use a situation where we can use the same instrument to measure both cases without moving it?

My example, then is the lifetime of muons. For those who don't know, muons are like heavy electrons and the spontaneously decay into an electron, a muon neutrino and an electron anti-neutrino. If we have a beam of muons, we can measure their exponential decay by counting the number of muons in two different locations. All we need to know is the time it takes for them to travel between the two detectors. Of course, this is just the distance between the detectors divided by the speed of the muons.

The equation describing the decay is as follows:

N(t) = N_0 e^(-t/T)

Here, N represents the number of muons, N_0 is the number of muons at time 0, and T is the lifetime (or, more properly characteristic lifetime) of the muons. If we measure the number of muons at two locations, the lifetime will be:

T = t/ln(N_0/N(t))

Or, in terms of the travel distance:

T = d/{v*ln(N_0/N(t))}

If there is no time dilation, T should be the same no matter what speed the muons travel at. However, it is actually observed that as the velocity of the muons increases, so does their lifetime. In other words, more muons get to the second detector than should.

Now, how do you interpret this with no time dilation?

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Hello all


I am new here but I love to read the different ideas.

Here is one way for a person to go faster than the speed of light.

If you can construct a ship that can generate a buble that you can drag space and time with you. This buble would have to be made at the same point in time and space that the earth is. You would then expand space behind it and the crush space in frount of the buble. This would give you speeds well faster than the speed of light. Plus you would keep the idea of Relativity intact.

I know this is not possable with our current techonogly. But mabe one day

Please let me know what you think.

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Cyrax_Darkmual@yahoo.com
Cyrax Darkmaul 94th Druid. Mob Killer
life is not measured by the breaths we take but by the moments that take our breath.

Hello Cyrax, You are very welcome to seti@home. You must be doing other
bionc projects judging by your credits.

I like your theory, even though i dont understand it. I just cannot make any sense out of it. But i bet stephen spielberg would know exactly what you are talking about.

The only reason i say that is that i only tend to believe what science can
prove for sure. Thats just me.

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Hello all


I am new here but I love to read the different ideas.

Here is one way for a person to go faster than the speed of light.

If you can construct a ship that can generate a buble that you can drag space and time with you. This buble would have to be made at the same point in time and space that the earth is. You would then expand space behind it and the crush space in frount of the buble. This would give you speeds well faster than the speed of light. Plus you would keep the idea of Relativity intact.

I know this is not possable with our current techonogly. But mabe one day

Please let me know what you think.

Sounds like one of the descriptions I've heard of the warp drive in Star Trek.

In fact, such a thing can be investigated using the mathematics of general relativity; and people have done so. While it is a perfectly well defined sort of mathematical structure, as far as we can tell it can't actually exist physically. It would require there to be regions in the universe with negative energy density. But, if anything existed which had negative energy density, it would ultimately mean that our universe is unstable; and there would be physical consequences of this which we should be able to detect and haven't.

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