Math/Sci-Fi Question

[Cybermancer]

I lack the knowledge and skills to find the answers to these questions on my own.

Assuming a maximum speed of 99.9999% the speed of light,
assuming a time of 365 days to accelerate to that speed (and to decelerate from that speed),
assuming a distance of 4.4 light years.

What is the rate of acceleration?
What is the 'g-force' from that acceleration?
How long does it take to cover the entire distance?
How much time appears to go by for those on the vessel due to time dilation?

Please explain your answer in simple laypersons terms and if possible, show your work.

Thank you for your assistance.

(P.S. I don't need to know things like required energy outputs but if you wish to include such, then by all means)

[Severus Snape]

I lack the knowledge and skills to find the answers to these questions on my own.

Google can be your friend.

Assuming a maximum speed of 99.9999% the speed of light,
assuming a time of 365 days to accelerate to that speed (and to decelerate from that speed),
assuming a distance of 4.4 light years.

To start: Light speed is 186,286 miles per second. Which would be 11,177,160 miles per minute (light speed * 60), or 670,629,600 miles per hour. 99.9999% of this would be 670,628,929.3704 miles per hour.

What is the rate of acceleration?

Well, that's a little tricky. You need to remember that acceleration is the rate at which velocity - not speed - changes. And it's going to be hard to determine the rate of acceleration. Why? Well, at the start you are not moving. You then start moving, and are attempting to get up to (near) light speed, over the course of 1 year. To calculate the rate of acceleration, we'll need to know how much speed you are gaining over every single day. If the amount of speed is the same every day, then you would be gaining 1,837,339.5325 mph every day until you reach your intended speed. We can calculate the rate of acceleration on this as:

Change in Velocity/Time for Velocity To Change

So the change in velocity is 1,837,339.5325 mph, and the time it takes to reach this amount of velocity is 24 hours. This means your rate of acceleration in this case is 76,555.813 mph^2 (71,555.813 miles per hour squared).

But this does not take into account that you are continuing to build speed through each consecutive day. Rate of velocity changes as speed increases. And you'll need a whole lot more math than I know to calculate this based on current speed, speed attempting to attain, speed gained, and distance traveled.

What is the 'g-force' from that acceleration?

This one is out of my reach.

How long does it take to cover the entire distance?

4.4 light years is what you are asking for. A light year is the distance light can travel in one year, which is 5,878,630,000,000 miles. 4.4 of these is 25,865,972,000,000 miles. That's the distance light can travel in a vacuum in 4.4 years. With me so far?

Now, you are reaching near light speed, which means you can only travel 5,878,624,121,370 miles in one year. And that's AFTER you reach near light speed. So in 4.4 light years, you would travel 25,865,946,134,028 miles. But again, this is after you've reached light speed. You have to account for the distance you travel in the first year first. And again, that math is dependent on the rate of acceleration. And that changes from day to day as you are increasing your speed. It also helps to know that the distance you can and do travel will change with each 1 mph increment in speed.

How much time appears to go by for those on the vessel due to time dilation?

365 days appear to go by for those on the vessel. They are travelling for 1 year per your statement, so it would appear to them that 1 year passed by.

[Cybermancer]

If it takes a year to get up to 99.9999% the speed of light and another year to decelerate from that speed and the total distance to be travelled is 4.4 light years, I'm not seeing how it only takes a year to travel that distance. At light speed, it's going to take 4.4 years to travel 4.4 light years. At less than that speed and taking into account a year to accelerate and decelerate it's going to take longer than that amount of time.

But that's the time relative to one who is not taking the trip.

I also need to know how long it takes for those taking the trip. Time will seem to go slower due to time dilation.

[Severus Snape]

If it takes a year to get up to 99.9999% the speed of light and another year to decelerate from that speed and the total distance to be travelled is 4.4 light years, I'm not seeing how it only takes a year to travel that distance. At light speed, it's going to take 4.4 years to travel 4.4 light years. At less than that speed and taking into account a year to accelerate and decelerate it's going to take longer than that amount of time.

But that's the time relative to one who is not taking the trip.

I also need to know how long it takes for those taking the trip. Time will seem to go slower due to time dilation.

I'm sorry if I confused you. I was originally under the impression that they were travelling only for a year.

For those on the ship, however long it takes for them to travel the specified distance is the amount of time that will pass. Meaning, they will be on the ship the whole time that they are travelling, and however long it takes is how much time will seem to pass to them.

Now, as far as how much time passes for those outside the ship, well...I'm not a quantum physics or relativistics theory professor or student, so I can't answer that. I know that, according to wikipedia:

Time dilation can be inferred from the observed fact of the constancy of the speed of light in all reference frames.

This constancy of the speed of light means, counter to intuition, that speeds of material objects and light are not additive. It is not possible to make the speed of light appear faster by approaching at speed towards the material source that is emitting light. It is not possible to make the speed of light appear slower by receding from the source at speed. From one point of view, it is the implications of this unexpected constancy that take away from constancies expected elsewhere.

and that

Thus the duration of the clock cycle of a moving clock is found to be increased: it is measured to be "running slow". The range of such variances in ordinary life, where , even considering space travel, are not great enough to produce easily detectable time dilation effects, and such vanishingly small effects can be safely ignored. It is only when an object approaches speeds on the order of 30,000 km/s (1/10 the speed of light) that time dilation becomes important.

Now, there are forumulas at wikipedia (this is the article you referenced) that tell one how to calculate the amount of time that has passed. However, and while I am pretty good at math, I am not that good. What you are trying to calculate cannot be done with simple algebra, nor can it be done by the average person. You need to go back to the original questions and figure out the following:

1. Rate of acceleration/velocity. This is the key component - Everything else pretty much depends on this.
2. Distance travelled in the first year. Remember that you don't travel the entire distance that light would travel in a year as you have to get up to speed first.
3. Amount of time it takes to travel the distance light would travel in 4.4 years.
4. The amount of time dilation relative to the passengers on the ship.

What we're talking about here is fairly advanced mathematics. And while I am quite certain there are people on these boards that may be able to tackle what you are asking, I'm also fairly certain that none of them will want to given the scope of what you're asking.

Which reminds me - why are you asking this anyhow? Is this for something in a campaign you're running/a part of?

[Natasha]

I'll give it a shot.

At 99.9999% of speed of light, the clock on rest frame (Earth, I assume) will be 1.937 years faster than clock on the ship. So if the voyage is 4.5 years on-ship; on Earth it's almost 9 years. (http://www.fourmilab.ch/cship/timedial.html)

99.9999% of speed of light = 299792158 m/s, and 1 year = 31556926 s.
So the average acceleration would be: (299792158 m/s)/(31556926 s) = 9.5 m/s^2.
That's less than 1 G; cosmonauts accelerate less than 4 G's to the so-called escape velocity (something like 11100 m/s).
Escape velocity is gravity against an object's kinetic energy (mass drops out, so velocity is what matters):
0.5 * m * v^2 = GMm/d, which simplifies as: v = sqrt(2GM/d).
Note that gravity obeys the inverse square law so gravity drops off quickly.
Note that here G is the gravitational constant (see below), not acceleration expressed in G's.

You can express acceleration in G's (a_g) by: a_g = F / mg
where F = force of accelerating ship (mass times acceleration),
m = mass of your ship, and
g = acceleration due to gravity.

As g approaches zero (get further from Earth, Sun, etc), the acceleration would likely become lethal to the passengers. Let's wave the hand of the GM here and say they survive.

Newton's law of gravitation says that the force of gravity is given by: F = GmM/d^2,
and by Newton's Second Law: Force is equal to mass times acceleration (F = ma).
So: ma = GmM/d^2
And because m cancels out, acceleration due to gravity on your planet is given by:
a = GM/d^2

where G is the gravitational constant = 6.673 * 10^-11 m^3 kg^-1 s^-2
a = acceleration due to gravity,
m = mass of your ship,
M = mass of your visited planet, and
d = distance between centers of each mass.

For me staying on the surface of earth, example:
m = (cancels out, even the Universe know better than to ask a girl this question)
M = 5.9742*10^24
d = 6378100 m

a = ((6.673*10^-11)(5.9742*10^24))/6378100^2
a = 9.799823 m/s^2 (close enough to the official answer, I think)

If I were flying away from the Earth and I reach already 55 million kilometers, it's 1.3 * 10^-7 m/s^2.

So, how long will it take?

Average velocity is given by: v_avg = (v_intial + v_final)/2
v_initial = 0, v_final = 299792158 m/s, so v_avg = 149896079 m/s.

Distance is average velocity times time: x = v_avg * t
v_avg = 149896079 m/s, and t = 31556926 s, so
x = 4.7 * 10^15 m (the distance your ship travels in a year).

4.4 light years is 4.16 * 10^16 m. Subtract the distance already traveled.
There remains: 3.69 * 10^16 m.

Again, by hand wavium, let's say that the ship covers the same distance over the year it is stopping as covered when the voyage began;
then there remains just 3.22 * 10^16 m, which the ship can cover in 107407746 seconds (going 99.9999% of speed of light), which is about 3.4 years. Add in the 2 years acceleration and decelerating: the clock on the ship says 5.4 years while clocks on Earth say 10.5 years.

[Severus Snape]

I'll give it a shot.

At 99.9999% of speed of light, the clock on rest frame (Earth, I assume) will be 1.937 years faster than clock on the ship. So if the voyage is 4.5 years on-ship; on Earth it's almost 9 years. (http://www.fourmilab.ch/cship/timedial.html)

99.9999% of speed of light = 299792158 m/s, and 1 year = 31556926 s.
So the average acceleration would be: (299792158 m/s)/(31556926 s) = 9.5 m/s^2.
That's less than 1 G; cosmonauts accelerate less than 4 G's to the so-called escape velocity (something like 11100 m/s).
Escape velocity is gravity against an object's kinetic energy (mass drops out, so velocity is what matters):
0.5 * m * v^2 = GMm/d, which simplifies as: v = sqrt(2GM/d).
Note that gravity obeys the inverse square law so gravity drops off quickly.
Note that here G is the gravitational constant (see below), not acceleration expressed in G's.

You can express acceleration in G's (a_g) by: a_g = F / mg
where F = force of accelerating ship (mass times acceleration),
m = mass of your ship, and
g = acceleration due to gravity.

As g approaches zero (get further from Earth, Sun, etc), the acceleration would likely become lethal to the passengers. Let's wave the hand of the GM here and say they survive.

Newton's law of gravitation says that the force of gravity is given by: F = GmM/d^2,
and by Newton's Second Law: Force is equal to mass times acceleration (F = ma).
So: ma = GmM/d^2
And because m cancels out, acceleration due to gravity on your planet is given by:
a = GM/d^2

where G is the gravitational constant = 6.673 * 10^-11 m^3 kg^-1 s^-2
a = acceleration due to gravity,
m = mass of your ship,
M = mass of your visited planet, and
d = distance between centers of each mass.

For me staying on the surface of earth, example:
m = (cancels out, even the Universe know better than to ask a girl this question)
M = 5.9742*10^24
d = 6378100 m

a = ((6.673*10^-11)(5.9742*10^24))/6378100^2
a = 9.799823 m/s^2 (close enough to the official answer, I think)

If I were flying away from the Earth and I reach already 55 million kilometers, it's 1.3 * 10^-7 m/s^2.

So, how long will it take?

Average velocity is given by: v_avg = (v_intial + v_final)/2
v_initial = 0, v_final = 299792158 m/s, so v_avg = 149896079 m/s.

Distance is average velocity times time: x = v_avg * t
v_avg = 149896079 m/s, and t = 31556926 s, so
x = 4.7 * 10^15 m (the distance your ship travels in a year).

4.4 light years is 4.16 * 10^16 m. Subtract the distance already traveled.
There remains: 3.69 * 10^16 m.

Again, by hand wavium, let's say that the ship covers the same distance over the year it is stopping as covered when the voyage began;
then there remains just 3.22 * 10^16 m, which the ship can cover in 107407746 seconds (going 99.9999% of speed of light), which is about 3.4 years. Add in the 2 years acceleration and decelerating: the clock on the ship says 5.4 years while clocks on Earth say 10.5 years.

And now my brain hurts. Thank you.

[Cybermancer]

Thank you very much, both Natasha and Severus Snape, that's exactly the information I needed.

The information is for use in a play test campaign that will eventually be submitted as a Chaos Earth/Rifts submission to the Rifter.

Basic concept, a colony mission was being prepped to leave for Alpha Centauri in the asteroid belt (yes, I'm aware that the odds of there being planets, much less habitible ones is abysmally small). The Rifts come and the mission is still a year from launch. The Chaos Earth portion deals with the mission trying to get underway (using tractions drives).

300 years later, the colonists, now well established, send an expedition back to the Sol system. Primary concern is the alien Arkhon's with an eye towards helping humans in the orbital community and on Earth after the alien menace is dealt with.

[Rallan]

Why are you people doing complicated math when you can pretty much work this out in your heads?

If it takes you a year of constant acceleration to get up to the speed of light, then your average speed during that year is half the speed of light, so you travel half a light year in your first year.

If you decelerate at the same rate, your average speed during your final year will also be half the speed of light, so that's another half a light year there.

So that's your first and last year of the voyage to cover a combined total of 1 lightyear.

That leaves 3.4 lightyears of the voyage left, but since you're travelling at roughly the speed of light you can just call that a travel time of 3.4 years in the middle.

So there you go, total travel time of roughly 5.4 years to travel 4.4 lightyears. Or almost but not quite 5 years and 5 months.

And I'm going to go out on a limb here and not even bother looking up the math, and say that to those on board it felt like roughly one year of subjective time (technically a little longer, since the middle of the voyage was spent at slightly below lightspeed).

As for acceleration, by a happy coincidence it just so happens that accelerating at 1G (9.8 metres per second squared) will get you to the speed of light in approximately one year (not exactly one year, but close enough that it'll feel almost like Earth gravity to the people on board for most of the trip).

[Natasha]

Why are you people doing complicated math when you can pretty much work this out in your heads?

If it takes you a year of constant acceleration to get up to the speed of light, then your average speed during that year is half the speed of light, so you travel half a light year in your first year.

If you decelerate at the same rate, your average speed during your final year will also be half the speed of light, so that's another half a light year there.

So that's your first and last year of the voyage to cover a combined total of 1 lightyear.

That leaves 3.4 lightyears of the voyage left, but since you're travelling at roughly the speed of light you can just call that a travel time of 3.4 years in the middle.

So there you go, total travel time of roughly 5.4 years to travel 4.4 lightyears. Or almost but not quite 5 years and 5 months.

That's exactly what I did, nothing complicated about it, I think.

And I'm going to go out on a limb here and not even bother looking up the math, and say that to those on board it felt like roughly one year of subjective time (technically a little longer, since the middle of the voyage was spent at slightly below lightspeed).

Meh. I just looked it up.

As for acceleration, by a happy coincidence it just so happens that accelerating at 1G (9.8 metres per second squared) will get you to the speed of light in approximately one year (not exactly one year, but close enough that it'll feel almost like Earth gravity to the people on board for most of the trip).

That's correct as long as they're close to Earth, but it won't take long to get to microgravity where the G's will go up quite a bit.

[glitterboy2098]

I lack the knowledge and skills to find the answers to these questions on my own.
Assuming a maximum speed of 99.9999% the speed of light,
assuming a time of 365 days to accelerate to that speed (and to decelerate from that speed),
assuming a distance of 4.4 light years.

What is the rate of acceleration?
What is the 'g-force' from that acceleration?
How long does it take to cover the entire distance?
How much time appears to go by for those on the vessel due to time dilation?

Please explain your answer in simple laypersons terms and if possible, show your work.
Thank you for your assistance.
(P.S. I don't need to know things like required energy outputs but if you wish to include such, then by all means)

assuming constant accelleration, to reach the speed of light (or infinitely close there to) in one year would require an accelleration of about 10 m/s^2, or about one gravity.
light speed is 299,792,458 meters per second. at 10 meters per second per second, reaching would take ([[[299,792,458/10]/60]/60]/24) = 346.9 days. a little less than a year, but close enough for roleplay.

for distance covered, that tricker. each second you'd be going faster, and thus cover a bit more ground.. the formula is to find the average velocity based on starting and finishing velocity, then multiply by the time. (V2-V1)/2
in this case, ((299,792,485 -0)/2)*29,972,160 = 4,492,714,163,608,800 meters

or 4,492,714,163,608.800 kilometers. or about 0.00449lightyears... or about 30,031.9 astronomical units

energy use is going ot depend on your drive system and it's efficency.
please also note this ignores alot of the effects of reletivity past .6c

for the crew, the elapsed time would be two years under one gravity of accelleration (one to get up to speed, one to decellerate), and 4.39 years of coasting, IE weightlessness.


the main problem with this approach is that once you get close to c, space dust hits like an atomic bomb. and even in the local bubble, densities are such you'd be hitting one speck a each second during the coasting phase, where one speck would hit like half it's mass in antimatter.

frankly, it would make more sense to build the ship as hollowed out asteroid based o'neil colony that can be spun to generate artificial gravity, and then use the traction drive at a much lower accelleration, such that you'd reach alpha centauri after a 50 year trip (25 years accellerating, then 25 years decellerating.)

[Cybermancer]

the main problem with this approach is that once you get close to c, space dust hits like an atomic bomb. and even in the local bubble, densities are such you'd be hitting one speck a each second during the coasting phase, where one speck would hit like half it's mass in antimatter.

frankly, it would make more sense to build the ship as hollowed out asteroid based o'neil colony that can be spun to generate artificial gravity, and then use the traction drive at a much lower accelleration, such that you'd reach alpha centauri after a 50 year trip (25 years accellerating, then 25 years decellerating.)

While you've raised some good points, 50 years won't work for a one way trip, at least not for what I'm setting up. Because there needs to have been a probe launched to determine that a suitable planet exists before an expedition could even start being planned. I actually have no problem with the colonists taking 50 years to get there (bigger ship=more time; makes sense in my laymen's mind). But I need to have a way for a probe to get there much faster. Twenty-five years or less (with less being quite preferable).

The time constraints are based on a few factors. The first is that I figure the mission would have had to be almost ready to go by the time the Rifts come. The second is I figure any probe would have to be launched 2050 or later. So in that 48 years or less, a probe has to make it to the destination, make the required observations and send them back. There also has to be a reasonable (by Rifts standards) amount of time for planning and construction.

So it looks like I'm going to be looking at solutions to the high speed impact delima that could possibly be implemented.

[Natasha]

http://www.nyu.edu/pages/mathmol/textbook/scinot.html

Do you know this number, 300,000,000 m/sec.?
It's the Speed of light !

Do you recognize this number, 0.000 000 000 753 kg. ?

This is the mass of a dust particle!

If that's true, then we have the energy of a dust particle being:
0.5 x (7.53 x 10^-10) x (3.0 x 10^8)^2 = 33,885,000 Joules of kinetic energy per particle.
Or 33.885 MegaJoules.

I think that glitterboy2098 has elsewhere attempted to calculate how many MegaJoules to 1 point of MegaDamage. If that's a compelling case, then you just pack on enough armour to see you through. How much armour is that? Well, you're the Game Master. So you could as well say that dust particles, no matter how fast, do not do M.D.

[Rallan]

http://www.nyu.edu/pages/mathmol/textbook/scinot.html

Do you know this number, 300,000,000 m/sec.?
It's the Speed of light !

Do you recognize this number, 0.000 000 000 753 kg. ?

This is the mass of a dust particle!

If that's true, then we have the energy of a dust particle being:
0.5 x (7.53 x 10^-10) x (3.0 x 10^8)^2 = 33,885,000 Joules of kinetic energy per particle.
Or 33.885 MegaJoules.

I think that glitterboy2098 has elsewhere attempted to calculate how many MegaJoules to 1 point of MegaDamage. If that's a compelling case, then you just pack on enough armour to see you through. How much armour is that? Well, you're the Game Master. So you could as well say that dust particles, no matter how fast, do not do M.D.

That last explanation will have players screaming "WHYYYYYY?" the moment they realise that every energy weapon in Rifts does damage using much smaller particles than dust, and most of them are travelling a lot slower than virtually lightspeed.

[Cybermancer]

I'm thinking that there are other ways of dealing with these particles.

For example, an electromagnetic or electrostatic ion scoop could be used to gather these particles for fuel as with a Bussard ramjet. Since traction drives have been chosen as the hand wavium technology to move the vessels at relavistic speeds, the problems of the ramjet are less pronounced. Such a device may also prove useful for deceleration at the target star.

[Natasha]

http://www.nyu.edu/pages/mathmol/textbook/scinot.html

Do you know this number, 300,000,000 m/sec.?
It's the Speed of light !

Do you recognize this number, 0.000 000 000 753 kg. ?

This is the mass of a dust particle!

If that's true, then we have the energy of a dust particle being:
0.5 x (7.53 x 10^-10) x (3.0 x 10^8)^2 = 33,885,000 Joules of kinetic energy per particle.
Or 33.885 MegaJoules.

I think that glitterboy2098 has elsewhere attempted to calculate how many MegaJoules to 1 point of MegaDamage. If that's a compelling case, then you just pack on enough armour to see you through. How much armour is that? Well, you're the Game Master. So you could as well say that dust particles, no matter how fast, do not do M.D.

That last explanation will have players screaming "WHYYYYYY?" the moment they realise that every energy weapon in Rifts does damage using much smaller particles than dust, and most of them are travelling a lot slower than virtually lightspeed.

Without a doubt; you're absolutely correct.

Still, they've already accepted that such a weapon can be held in the hands of a toddler, so they would just have to accept the mystery, I suppose.

[glitterboy2098]

While you've raised some good points, 50 years won't work for a one way trip, at least not for what I'm setting up. Because there needs to have been a probe launched to determine that a suitable planet exists before an expedition could even start being planned.

actually, probes aren't required, since golden age tech would suffice to detect planets via telescope. we can already do this and take spectroscope readings to determain if the world is habitable or not.

plus, if you really want probes, you could send a probe much faster than a manned ship. not only i a probe unmanned, and thus expendable, but they'd also be somewhat smaller, and thus less likely to be hit. they're also safer to use things like magnetic feild based particle defenses on. (use a UV laser to ionize particle in your path, and a ultra massive magnetic feild to repel them. the problem being that unless you line the ship with a superconductor material for Em protection, it'll destroy electronics and kill living beings at the strength needed. probes are smaller, and can thus be so sheilded. manned ship would have to settle for weaker feilds to protect against radiation only, and use physical armor and slower speeds for dust and stuff.)

I actually have no problem with the colonists taking 50 years to get there (bigger ship=more time; makes sense in my laymen's mind). But I need to have a way for a probe to get there much faster. Twenty-five years or less (with less being quite preferable).

The time constraints are based on a few factors. The first is that I figure the mission would have had to be almost ready to go by the time the Rifts come. The second is I figure any probe would have to be launched 2050 or later. So in that 48 years or less, a probe has to make it to the destination, make the required observations and send them back. There also has to be a reasonable (by Rifts standards) amount of time for planning and construction.

So it looks like I'm going to be looking at solutions to the high speed impact delima that could possibly be implemented.

a laser Broom comes to mind. though at the strength needed, you'd be able to blow craters into the moon from the earths surface if you focused it as a weapon. but sweeping the path ahead with a laser to "push" the particle out of the way....it could work.

[Cybermancer]

A probe is required for two reasons.

One, while telescopes and spectral analysis will indeed tell a lot about a planet, you're not going to want to risk your life and the lives of your children and grand-children on that data alone. You're going to want to have detailed information about microbes and so forth. You're going to want to have as much specific data as you can get before departing.

Two, it proves the technology necessary to make the trip. Because again, you're risking your life and those of your fellow colonists.

Compared to human life, probes, even those that span interstellar distances are cheap and expendable.

[Natasha]

A probe is required for two reasons.

One, while telescopes and spectral analysis will indeed tell a lot about a planet, you're not going to want to risk your life and the lives of your children and grand-children on that data alone. You're going to want to have detailed information about microbes and so forth. You're going to want to have as much specific data as you can get before departing.

Two, it proves the technology necessary to make the trip. Because again, you're risking your life and those of your fellow colonists.

Compared to human life, probes, even those that span interstellar distances are cheap and expendable.

Meh. Change your alignment.

[Cybermancer]

A probe is required for two reasons.

One, while telescopes and spectral analysis will indeed tell a lot about a planet, you're not going to want to risk your life and the lives of your children and grand-children on that data alone. You're going to want to have detailed information about microbes and so forth. You're going to want to have as much specific data as you can get before departing.

Two, it proves the technology necessary to make the trip. Because again, you're risking your life and those of your fellow colonists.

Compared to human life, probes, even those that span interstellar distances are cheap and expendable.

Meh. Change your alignment.

Or get stupid colonists.

Or both.

[dragonfett]

Remember, the probe doesn't need to return, it only need to get to it's destination and make it's observations then beam back its findings. The findings will get back to Earth long before the probe will (by about a year or so).

And sleekjag is right, why bother with all of these details? All you really need is a ballpark estimate and hand wavium it from there.

[Cybermancer]

Remember, the probe doesn't need to return, it only need to get to it's destination and make it's observations then beam back its findings. The findings will get back to Earth long before the probe will (by about a year or so).

And sleekjag is right, why bother with all of these details? All you really need is a ballpark estimate and hand wavium it from there.

I don't agree that sleekjag is right.

These details may not be important to you or sleekjag but they are to some players and readers. It's also important for writers to research their material so that any hand wavium applied is used judiciously. Too much hand wavium can ruin an otherwise good story for some. Considering the information was easily gained simply by asking for it, I don't see the issue.

As to the probe, I never said anything about it returning. But the information does have to return and is limited by the speed of light just like everything else in the universe. In this case it will take 4.4 years for information to return to Earth after the probe arrives.

Although all of this is pretty much academic at this point. The question was asked, answered and then used in the campaign. The first submission to the Rifter was also sent about two weeks ago.

[dragonfett]

More power to you then. Some people like it, others don't. And I also said just get a ballpark figure and pretty take it from there. In reality, there are so many more factors and variables that we haven't even thought of yet that would concern a trans-solar voyage.

[dragonfett]

I thought in Star Wars, they go into Hyperspace, which bends space and does not conform to normal rules of Time and Space.

[Warwolf]

And this is why, for my ship design material, I have pretty much thrown time dilation effects out the window for all Palladium space settings. Otherwise, you need something like PtP or "wormhole" technology to create a space opera setting that is both involved and compelling in my humble opinion. Thus, if my stuff ever sees print and goes into canon, expect the need for the accounting for time dilation to go out the window (i.e. the laws of astrophysics simply work differently within the Megaverse than our own universe, thus eliminating some of the need for us hard-corps versimilitude guys and gals to try and enforce "real world" standards of science on a fantastical setting).

[glitterboy2098]

actually, time dilation's not really a problem until you get over .6c, at which point it becomes an asymptomic problem.

this means that no palladium space setting ever has to worry about it, since there are no settings where speeds get over .6c. (phase world has fluf stating .6c is the max for contragravitics, the old robotech never got above .6c, and most of the rest barely even get to .01c)

any travel over .6c is thus inviarably using a faster than light drive, which being 'handwavium', can simply ignore Reletivity.

[dragonfett]

What is .6c?

[Cybermancer]

What is .6c?

60% the speed of light.

[dragonfett]

Thanks

[Cybermancer]

Thanks

You're welcome.

[Rallan]

In reality, there are so many more factors and variables that we haven't even thought of yet that would concern a trans-solar voyage.

For example, the speed of light is measured in a vacuum. Space isn't a perfect vacuum. If it were, planets wouldn't be possible.

Even if you could go 99.9999% the speed of light, there still might be slow points and fast points. Not to mention the typical inability to slow down when your going that fast - honestly, that's the most amazing part of Star Wars or Star Trek - they can stop after going that speed...
-Pax

Well no it's not amazing, because in Star Wars and Star Trek they're using "sufficiently advanced technology" that does whatever the writers want it to. And since that sufficiently advanced technology isn't even described as working the way you seem to think it works, there's nothing particularly amazing about what you've just mentioned

[Rallan]

actually, time dilation's not really a problem until you get over .6c, at which point it becomes an asymptomic problem.

this means that no palladium space setting ever has to worry about it, since there are no settings where speeds get over .6c. (phase world has fluf stating .6c is the max for contragravitics, the old robotech never got above .6c, and most of the rest barely even get to .01c)

any travel over .6c is thus inviarably using a faster than light drive, which being 'handwavium', can simply ignore Reletivity.

And there you're wrong, since Traction drives (available both in Mutants In Orbit and in Phase World, althoug it's an obsolete low-tech way of doing things in Phase world) allow for indefinite acceleration up to the speed of light. As you would've known if you'd bothered to actually read this thread

And it's particularly problematic in Mutants In Orbit, because traction-drive ships there are able to reach any planet in the solar system in a few weeks at most, and a long range mining or scouting trip to the outer reaches of the Oort Cloud would only be a few months either way. And since in the current setting (where the writers never sat down and did the math) people are described as being perfectly willing to travel via chemical-drive ships for several months just to reach the asteroid belt, then it stands to reason that if any NPC in Mutants In Orbit ever magically gets better at highschool physics than Kevin Siembieda, they'll be quite willing to go on voyages to the outer solar system which will involve travelling at high enough fractions of c for time dilation to become pretty darn noticable.

[cornholioprime]

It's your game just make it up. Is it scientific no but are you playing with a bunch of physicist that will call you out on it probally not. There's plenty of math to work with in the thread so just go with what works for the campaign. No big deal. But have to give a big thinks to those that did the math.

What he said.

"Forget" the Science.

For just one thing....don't they say somewhere that due to extreme time dilation on the part of the lightspeed traveler, that it only takes a single hour of lightspeed travel for a thousand years to pass for the rest of us not on the ship??

Even the indestructible walls of Center in the Three Galaxies will start rusting by then, the journey will take so "long!"

[Rallan]

For just one thing....don't they say somewhere that due to extreme time dilation on the part of the lightspeed traveler, that it only takes a single hour of lightspeed travel for a thousand years to pass for the rest of us not on the ship??

Something like that. As you approach the speed of light, the amount of time dilation you get increases exponentially, which means that the amount of time you get approaches zero.

At 90% of the speed of light, you could travel for a thousand years and experience about 450 years of subjective time.

At 99% your thousand year voyage feels like about 140 years subjectively.

At 99.9% it's only about 45 years.

If we were to kick it up a notch and travel at 99.99999999999934% of the speed of light, you'd get your thousand year voyage that feels like an hour.

And at lightspeed itself (which in theory is impossible, rather than just insanely difficult like those previous speeds), your thousand year voyage feels like no time at all. To the outside world you've travelled at the speed of light for a millenium. To you, you've travelled a thousand lightyears in an instant.

[Cybermancer]

OH MY GOD I CAN SEE FOREVER


You can save yourself all this trouble by declaring they hit an asteroid in the 10th month of acceleration and all die.

Rocks fall and everybody dies?

Bad form, poor GMing and general jerkiness all wrapped up and rolled into one.

Thanks but no thanks.

[Rallan]

OH MY GOD I CAN SEE FOREVER


You can save yourself all this trouble by declaring they hit an asteroid in the 10th month of acceleration and all die.

Rocks fall and everybody dies?

Bad form, poor GMing and general jerkiness all wrapped up and rolled into one.

Thanks but no thanks.

It is something that you might have to find a way around though. If this sort of epic space voyage is just a very occasional thing, then you can sorta gloss over it and hope nobody asks questions. But if puttering around with ships that can travel at almost the speed of light is a common part of your campaign, you'll need to come up with an explanation for why nobody ever faceplants into a planetoid that they didn't see, or nobody gets ripped apart when they impact a golfball-sized piece of debris with the relative mass of the Titanic.

[Cybermancer]

The voyage out at light speed is going to be pretty much a singular, once in human history event. I'm using a MacGuffin that basically moves particles and debris around the ship as it moves through space. The ship will also use laser brooms and then just avoid anything too big.

I have other plans for the voyage back. They won't be travelling in normal space at all.

[Rallan]

The voyage out at light speed is going to be pretty much a singular, once in human history event. I'm using a MacGuffin that basically moves particles and debris around the ship as it moves through space. The ship will also use laser brooms and then just avoid anything too big.

I have other plans for the voyage back. They won't be travelling in normal space at all.

In that case, don't fret the details too much. Whatever handwavium you use to justify the lack of crashed is good enough.

All you have to do is figure out what they'll do during the voyage. Because even if their top speed is so close to lightspeed that it seems almost instantaneous, you've still set yourself a long acceleration/deceleration time at either end.

[glitterboy2098]

even at lightspeed, a trip to alpha cent would be a bit under 5 years. plus the year or so on each end to speed up, slow down. so at least 7 years to get there. at a speed where getting hit with a stray cosmic ray is like being nuked, and even dust can gut a ship. and there is no mechanism to "move debris around the ship" that doesn't completely break physics, even more than traction drive does. even traction drive is constrained by conservation of energy and momentum..it just uses spatial warping to go from energy to movement directly.

if this trip is a onetime only deal, slow it down, use armor and laser brooms, and put the whole thing on a mobile asteroid so you have a large enclosed setting before you even reach alpha cent.

[Rallan]

even at lightspeed, a trip to alpha cent would be a bit under 5 years. plus the year or so on each end to speed up, slow down. so at least 7 years to get there. at a speed where getting hit with a stray cosmic ray is like being nuked, and even dust can gut a ship. and there is no mechanism to "move debris around the ship" that doesn't completely break physics, even more than traction drive does. even traction drive is constrained by conservation of energy and momentum..it just uses spatial warping to go from energy to movement directly.

if this trip is a onetime only deal, slow it down, use armor and laser brooms, and put the whole thing on a mobile asteroid so you have a large enclosed setting before you even reach alpha cent.

Um, dude? We already covered all of that. Including the bits that you either forgot to mention or didn't know about, like the time dilation effects of travelling almost as fast as the speed of light which would make the journey seem much shorter for the people on board.

[Cybermancer]

even at lightspeed, a trip to alpha cent would be a bit under 5 years. plus the year or so on each end to speed up, slow down. so at least 7 years to get there. at a speed where getting hit with a stray cosmic ray is like being nuked, and even dust can gut a ship. and there is no mechanism to "move debris around the ship" that doesn't completely break physics, even more than traction drive does. even traction drive is constrained by conservation of energy and momentum..it just uses spatial warping to go from energy to movement directly.

if this trip is a onetime only deal, slow it down, use armor and laser brooms, and put the whole thing on a mobile asteroid so you have a large enclosed setting before you even reach alpha cent.

1. The MacGuffin is linked to the traction drive and frankly, doesn't break physics any more or less than the traction drive. Both do equally impossible things. In that something either is possible by physics or it is not. There are no degrees in between.

2. So far as the Rifter article, it's written as an optional feature which a GM can ignore or not include. The option for a longer trip is also included. Either for GM preference or due to failure of the players to get the MacGuffin.

3. Already mentioned that I'm using laser brooms on it. Look up thread for that.

4. It is an armored asteroid.

5. How it has played out in my campaign and the baseline assumption for the article (already submitted) is that it will be accelerate at 1G until reaching nearly the speed of light. Then it will coast for most of the journey before decelerating at the other end.

I needed to know the length of actual time and time dilation effect for the crew in order to work out a timeline (and optional alternate timeline) to fill the gap between departure (the conclusion of the orbital Chaos Earth adventure) and current Rifts era.

BTW, to all. I could have sworn I read about a Neptune mission in a Rifter someplace set in the Chaos Earth timeframe but haven't been able to locate it since. It had a real horror feel to it. Maybe I dreamed it after watching Event Horizon or something. I have all the Rifters (except 52 which just came out) so I'm wondering if I'm just not seeing it or something. Is this article real and if so, what Rifter did it appear in? Page number too, if you can. Thank you.

Just as a general update.

The Chaos Earth adventure has been run in my group, they enjoyed it. I've begun play testing some features of what I'll be including in the follow up article. The players have enjoyed it and it seems to be working out from a game balance perspective. I'm still filling in the 'in between' details between the two eras although I have a fairly broad outline done. Just some details to sort out. I'm including alternate notes and timelines so that it can be ran to taste. It seems like a good way to take advantage of the fact that the Rifter is not canon material. I'm also seeing it as an experiment in having player actions effect meta-plot. Orbit also serves well in this respect as the setting is isolated from the rest of the Rifts world.

[Cybermancer]

Recently came up with a new idea of how to build the colony vessel. It's going to be a constructed spacecraft on the same engineering scale as the space stations in orbit. I originally had planned for the hollowed out asteroid concept but ultimately I liked this design better. And based on the scale of engineering projects already taking place during the golden age of man, it seemed feasible. The best part of this is that it allows me to reuse the design and indeed the very ship for a return voyage to earth in the current time (109-110 PA)

I have slowed down the speed of the journey to Alpha Centauri significantly. This is part due to the deletion of the traction drives. I've replaced them with nuclear pulse drives instead.

Basically the new design is a space station with engines added and designed to establish an extra solar colony.

I also changed the name to the United Nations Colony Vessel (UNCV) Jupiter.

Here are the basic stats I wrote up for it last night. Still a work in progress at this point.

I'd like to thank everyone who has contributed ideas thus far. I'd like to single out glitterboy2098 for special thanks in his assistance both in this thread and in PM. I haven't used all your ideas and suggestions but I have toned down the 'fantastic' and dialed up the science. Plus I've learned a lot of interesting things along the way.

Just hit the spoiler tag to see the stats and history.

Spoiler:

UNCV Jupiter

While assembly of the UNCV in orbit began in 2090, conceptional designs started as far back as 2070. New technologies were tested in the missions to Mars, and the follow up missions to Alpha Centauri. Construction on components on the earth, the moon and the space stations began as early as 2080. One of the most important design features was the inclusion of an A.R.C.H.I.E. artificial intelligence to increase automation and efficiency throughout the trip and after arrival at the new colony.

The Jupiter has several key areas and features. The first is the primary hull. It is roughly square shaped with the main engines and forward engine attached to either end. It is approximately 250m across (not counting the habitat rings) and with the engines, about 3.2kms long. Inside this hull are where the majority of the crew and their animals are kept in stasis. Supplies of all sorts are also stored in this part of the craft. The ships operations center is in the very center of the ship. The A.R.C.H.I.E. computer is found in the operations center. Without the operations center, the vessels systems have to be all run manually which requires waking up the entire 8,000 person crew.

Attached like bearings to the hull are three habitation rings. These rings are about 100m thick and have 20 levels. Spin is calculated so that the outer level has gravity equal to their destination planet. Only one of these rings (the center one) will be in use and spinning during the voyage. It is where the active crew will spend the majority of their time. The other two rings will be activated shortly before arrival so that the colonists will have a comfortable place to stay after being woken up and before being ferried to the new planet.

There are four secondary hulls attached to the primary hull through a series of structural supports. These four secondary hulls are then attached to each other with more supports. These secondary hulls carry the missions gear including vehicles, robots and industrial equipment. They also have additional large storage areas for additional colonists, animals and various plant life. Each of the secondary hulls is named for the four largest moons of Jupiter (Io, Europa, Ganymede and Callisto).

Attached to the sides of these hulls are automated mining and transport vessels that are intended to mine asteroids and moons in the Alpha Centauri system after arrival. They can also be used to refurbish the Jupiter for a return voyage.

Attached to the 'top' of each hull are six landing ships that will carry the colonies industrial infrastructure to the planet after arrival. Each one will 'unpack' after landing to become a new automated seed factory for the colony.

The engines are larger and more powerful versions of the nuclear pulse rockets that carried the first unmanned probe to Alpha Centauri. These engines work by having rail guns fire shaped nuclear charges through a hole in a pusher plate. Once past the pusher plate, the nuclear warhead detonates and the kinetic energy created pushes against the pusher plate, propelling the vehicle forward. The pusher plate is made of ablative armor that can absorb both the heat and kinetic energy of the blast. Two layers of shock absorbers cushion the impact so that the crew and payload feel a smooth acceleration rather than being jerked forward.

There are twelve of these engines in the rear of the vehicle. Only four of them are needed to propel the vehicle forward but additional engines were added to the secondary hulls to provide those hulls with self sufficiency in the event of an emergency. It also provided the vessel with increased redundancy in the event of catastrophic damage to one part of the engine system.

In the front of the primary hull is a single large nuclear pulse rocket. This engine is used to slow down and stop the vessel. It can also be used to propel the vessel in reverse. It was decided that adding a reverse rocket was less risky to the craft than exposing the broadside of the vessel to dust and micro-meteorites while attempting to turn it around at a significant portion the speed of light. It also meant that laser brooms wouldn't have to be installed in the rear of the vessel. Finally, the deflector plate from this engine can absorb some of the damage that high speed travel in space can inflict.

Model Type: Jupiter

Class: Interstellar Colony Vessel

Crew: 1,000 personnel at one time. There are eight shifts. Only one shift is out of stasis at one time. In addition to the 8,000 total crew, there are 50,000 colonists embarked, in stasis.

Ancillary Vehicles of Note:

24 Landing Craft
24 Mining Drones
8 Ferry Vessels
48 Shuttle Craft
400 EVA Craft
50 water craft of various types
200 air vehicles of various types
800 land vehicles of various types
5000 robot drones of various types

M.D.C. By Location:
Interior Bulkheads per 10 feet (3m)-40
Interior Hatches-35 each
Exterior Hatches-40 each
*Laser Broom Emitters (60 total)-500 each
**Forward Nuclear Pulse Rocket (1)-25,000
Main Hangar Doors (8)-10,000 each
Apollo Class Landing Ships (24)-10,000 each
Artemis Class Mining Vessels (24)-10,000 each
Primary Support Struts (48)-5,000 each
Habitat Rings (3)-20,000 each
Forward 1/3 of Primary Hull-50,000
***Middle 1/3 of Primary Hull-50,000
Rear 1/3 of Primary Hull (Fuel Storage)-40,000
Forward 1/3 of Secondary Hulls (4)-35,000 each
Middle 1/3 of Secondary Hulls (4)-35,000 each
Rear 1/3 of Secondary Hulls (Fuel Storage; 4)-25,000 each
Rear Engine Support Struts (8)-2,500 each
****Main Nuclear Pulse Rockets (12)-5,000 each
*Destruction of up to have the laser brooms means that the ship will not be able to safely exceed 4% the speed of light. Destruction of all the laser brooms will mean that the ship will not be able to safely exceed 1% the speed of light.
**Destruction of the forward nuclear pulse rocket will mean the ship will have to make a dangerous flip over manoeuvre half way through its journey in order to slow down and eventually stop.
***Destruction of the middle 1/3 of the primary hull will destroy the ships primary command and control, and A.R.C.H.I.E.-6. The ship is not disabled however and can still be controlled but all automation is lost. You will also kill 1/3 of the colonists and animals in stasis.
****Destruction of all the main nuclear pulse rockets will mean that the ship will only be able to fly in reverse. Destruction of all nuclear pulse rockets, front and rear, leaves the ship with manoeuvring thrusters only. If the ship was at any notable speed at all, then it will no longer be able to slow down.

Speed:
Atmosphere: The Jupiter has no ability to fly in an atmosphere. It should remain at least 200 miles away from any Earth like planet.
Sub-light: The Jupiter is designed to average 30% the speed of light during its voyage to Alpha Centauri. Due to not being complete upon launch, it will only average 10% the speed of light during the voyage. Maximum acceleration is 4G's which can be maintained for 5 days. Typical acceleration is 1G and can be maintained for up to 30 days at a time.
Range: The Jupiter class colony vessel is designed to travel up to 15 light years on missions up to 50 years in duration with an active crew of 1,000 personnel. Upon arrival, the ship can be refitted and resupplied in 1-4 years for a return voyage assuming no major damage has been taken. In the vessels current state, it will barely reach Alpha Centauri and will take 44 years to do it.

Statistical Data:
Length: 10,948ft or about Two miles long (3.2kms)
Height and Width: 3,937ft (1.2kms)
Mass: 100 million tons fully fuelled and loaded.
Cargo: 50,000 colonists in stasis, animals, food, medicine, building materials and supplies needed to start a colony on a new planet.
Power System: 2 fusion reactors (primary hull) and 8 supplementary fusion reactors (two in each secondary hull).
Construction Cost: The entire Alpha Centauri colonization project cost 5 trillion dollars USD split amongst the developed nations of the world. With the completion of the first Jupiter class vessel nearly complete, it was estimated that additional vessels of the class could be constructed for about 500 billion dollars USD each. Even at that price, there was a great deal of controversy over whether or not any more should be built. Of course, with the coming of the Rifts, the point has been rendered mute as additional ships are not possible at any price.

Weapon Systems:
While not a warship, it is not exactly helpless either.
Any vessel caught in the exhaust plume (10,948ft or about Two miles long/3.2kms) of either its main pulse nuclear rockets or forward pulse nuclear rocket will take damage based on the acceleration at the time. Damage is equal to 1D4X100 M.D.C. per G of acceleration to a maximum of 4 G's.

Furthermore, shaped nuclear charges can be fired via their rail gun injector cannons up to 100 miles away. These nuclear warheads can be used as mines or fired directly at a target. Each one does 1D4X100 M.D.C. each.

Likewise, the laser brooms can sweep the area around the ship out to 100 miles, doing 2D6 M.D.C. To everything in the area per melee round. Or they can be focused on individual, star ship sized targets within 30 miles. In this case they do 5D6X10 M.D.C. per shot (each one can fire twice per melee round). Up to 36 of these emitters can engage targets in front of the vessel. Up to 26 can engage from a 'side' barrage. Only 8 are positioned to fire to the rear of the vessel. Generally speaking, only 8 will be used to target a single target at any given time.