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Posted 2/9/17

auroraloose wrote:


Darkphoenix3450 wrote:

You seem good at math so assume you can understand what changes you have to do to your formulas. 1. The railgun is on a space station not on earth so G-force is not a factor.(allowing to reach greater speeds much quicker without affecting the passengers. 2. The computer onboard the shuttle controls the sails, not to be used to propel the object, but instead used to adjust the path in witch the shuttle is moving allowing shuttle changes to direction, course correction. 3, structural soundness of shuttle (shuttles outer shell will be shaped almost egg like, created from a titanium, Tungsten highbred created using explosion welding.) 4. Of course targets for colonization will be found before launch. After all we are already doing that, and found 138 or so possible earth like planets that can meet are needs. 5. you forgot to add in speed + time dilation into you factoring. 6. this is a one way trip so landing would be most likely a parachute style. Now with those factors feel free to readjust your numbers.


iriomote seems to know what he's talking about. All of these points (except the relativity one) are basically irrelevant to the calculations - and the part in red is complete nonsense: Newton's second law says that force equals mass times acceleration. Gravity is not necessary for acceleration. If you're being accelerated by a railgun, that's acceleration, and you're going to experience a force (crushing you). Whether or not you're in space has nothing to do with it.

Now, if iriomote did indeed forget the relativistic correction - which we don't even know - it wouldn't change things much: at 8.5% of the speed of light, you'd multiply the distances by about 0.97 - and hence the necessary time by 0.97. I don't remember the correction during acceleration off the top of my head, though.

For the other questions, I think I agree with Ravenstein's opinion. I should also say that EM drives are nonsense, because they violate conservation of momentum.


Please at least browse the article before you say it is nonsense. They have proven effective in labs by NASA and other groups. Sure the scientists aren't exactly sure HOW it works, but they can prove that it does. It goes into math that is way over my head dealing with quantum space. Here is a recent article about it:
http://www.sciencealert.com/it-s-official-nasa-s-peer-reviewed-em-drive-paper-has-finally-been-published
And here is a selection from it in case you don't bother to read it.

It's very similar to the paper that was leaked online earlier this month and, most notably, shows that the drive does indeed produce 1.2 millinewtons per kilowatt of thrust in a vacuum:


"Thrust data from forward, reverse, and null suggested that the system was consistently performing at 1.2 ± 0.1 mN/kW, which was very close to the average impulsive performance measured in air. A number of error sources were considered and discussed."

To put that into perspective, the super-powerful Hall thruster generates force of 60 millinewtons per kilowatt, an order of magnitude more than the EM Drive.

But the Hall thruster requires propellants, and that extra weight could offset the higher thrust, the team concludes.

Light sails on the other hand, which are currently the most popular form of zero-propellant propulsion, only generate force up to 6.67 micronewtons per kilowatt – two orders of magnitude less than NASA's EM Drive, says the paper.

But the team makes it clear that they also weren't attempting to optimise performance in these tests – all they were doing was trying to prove whether or not the drive really works. So it's likely that the EM Drive could get a lot more efficient still.

Yes. NASA Eagleworks. As in the guys wearing the big boy pants when it comes to space travel, have PROVEN that it works.
Posted 2/9/17

Lockgor wrote:


Sir_jamesalot wrote:

2 and 3 can be solved with cannibalism.


I contend that problem 1 can also be solved with cannibalism.


Woops, I when I said "2" meant "1".
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Posted 2/9/17

auroraloose wrote:


Darkphoenix3450 wrote:

You seem good at math so assume you can understand what changes you have to do to your formulas. 1. The railgun is on a space station not on earth so G-force is not a factor.(allowing to reach greater speeds much quicker without affecting the passengers. 2. The computer onboard the shuttle controls the sails, not to be used to propel the object, but instead used to adjust the path in witch the shuttle is moving allowing shuttle changes to direction, course correction. 3, structural soundness of shuttle (shuttles outer shell will be shaped almost egg like, created from a titanium, Tungsten highbred created using explosion welding.) 4. Of course targets for colonization will be found before launch. After all we are already doing that, and found 138 or so possible earth like planets that can meet are needs. 5. you forgot to add in speed + time dilation into you factoring. 6. this is a one way trip so landing would be most likely a parachute style. Now with those factors feel free to readjust your numbers.


iriomote seems to know what he's talking about. All of these points (except the relativity one) are basically irrelevant to the calculations - and the part in red is complete nonsense: Newton's second law says that force equals mass times acceleration. Gravity is not necessary for acceleration. If you're being accelerated by a railgun, that's acceleration, and you're going to experience a force (crushing you). Whether or not you're in space has nothing to do with it.

Now, if iriomote did indeed forget the relativistic correction - which we don't even know - it wouldn't change things much: at 8.5% of the speed of light, you'd multiply the distances by about 0.97 - and hence the necessary time by 0.97. I don't remember the correction during acceleration off the top of my head, though.

For the other questions, I think I agree with Ravenstein's opinion. I should also say that EM drives are nonsense, because they violate conservation of momentum.


'Ok lets talk science.. A spaceship could get to Pluto in 18 to 20 days by accelerating at 1g all the way, but reversing direction halfway between so it can come to a stop. If you don't care to come to a stop, it's only 13 days if one accelerates at 1g all the time.

'The Human Body can withstand a Constance of 5g. So change in time in going from rest to 0.99 c (c being speed of light)

t = change in momentum divided by the force,

the force being a constant (mrest) x (a), where
mrest is the mass of the object at rest
and 'a' is the acceleration of the object.

At relativistic speeds, the relativistic mass is considerably larger than
the rest mass, or

mass = mrest divided by the square root of (1 - beta squared), where
beta is the ratio of the object's speed and the speed of light (v/c)

The velocity is just 0.99 c, or the relativistic momentum is

p = [ mrest (beta) c ] divided by the sq. root of (1 - beta squared)

If beta is 0.99, 1-beta is 0.01 and the square root of same is 0.1, or

p = mrest (0.99) c / 0.1 = 9.9 mrest c

Finally,

time = change in momentum / force

= [ 9.9 mrest c ] / [ mrest a ] = 9.9 c / a

That's the time elapsed in accelerating from rest to 0.99 of the speed of
light is simply 9.9 times the speed of light divided by the acceleration
rate.

For c = 3 x e 8 meters per second and
g = 9.8 meters / second second [ or meters per second squared ],

and knowing that 1 year equals 3.156 e 7 seconds

at 5g it takes about 2 years to reach 0.99 c.

Now we need to add in Time Dilation

t’: is the time that passed by for the moving clock;
t: is the time that passed by in the reference system;
v: is the speed of the moving clock;
c: is the speed of light.

With this formula we can understand how long it take to reach a planet 25 light years away or more, and but also the time inside the ship that has passed.


Just so you know using this math if I was to leave earth to head to another planet 20 light years away at the age of 36, I still be under 50 by the time I make it. So yes We can live long enough to travel to other planets around other stars.
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Posted 2/9/17

auroraloose wrote:

iriomote seems to know what he's talking about. All of these points (except the relativity one) are basically irrelevant to the calculations - and the part in red is complete nonsense: Newton's second law says that force equals mass times acceleration. Gravity is not necessary for acceleration. If you're being accelerated by a railgun, that's acceleration, and you're going to experience a force (crushing you). Whether or not you're in space has nothing to do with it.

Now, if iriomote did indeed forget the relativistic correction - which we don't even know - it wouldn't change things much: at 8.5% of the speed of light, you'd multiply the distances by about 0.97 - and hence the necessary time by 0.97. I don't remember the correction during acceleration off the top of my head, though.

Eh, I didn't forget so much as didn't bother (in my defense, I did say I was being sloppy). Dusting off special relativity for discussion on an anime forum felt like too much work and I'm generally in a lazy mood when I come here. I knew that time dilation in my example would only cause a relatively (eh? eh? ) trivial difference for the hypothetical colonists and, since they would be so far out of contact with Earth either way, the point would be rather academic.

When I was running the numbers I estimated the time difference would probably be a year or so at most, so I decided I wasn't being paid enough to care. Huh.. I think I just heard my physics professor (wherever he is these days) screaming in horror.

While half-assing the time dilation formula right now, I got a difference of about 2 and a half months. So if my math isn't wholly wrong, the 50 year journey would take about 49 years, 9 months and 15 days from the colonists' perspective. You could essentially call it a rounding error.
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Posted 2/10/17 , edited 2/10/17

MadBovine wrote:

Please at least browse the article before you say it is nonsense.


I am a theoretical physicist; I already know about (and have read about) the EM drive, and I also know how absurd it is to violate conservation of momentum, or to talk of pushing off of the field theory vacuum. You'll note that the way the ScienceAlert piece talks about the drive, it hides all the possible sources of error by quoting the NASA paper as having "considered and discussed" them. Try this Discover piece instead, or this one, which is even more telling.


MadBovine wrote:
Yes. NASA Eagleworks. As in the guys wearing the big boy pants when it comes to space travel, have PROVEN that it works.


Science doesn't prove anything; it only tells us what probably comports with reality. There is way too much room for errors to pop up in this experiment, and all scientists with level heads expect someone to find the errors in this group's methodology.

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Posted 2/10/17

iriomote wrote:

Eh, I didn't forget so much as didn't bother (in my defense, I did say I was being sloppy).


Of course - I too wouldn't bother with the relativistic effects here; I just wanted to point out that, as you didn't actually show what you did (because why would you do such a thing on an anime forum), Darkphoenix3450 wouldn't even be able to tell if you forgot about relativistic effects.

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Posted 2/10/17

Darkphoenix3450 wrote:

'Ok lets talk science.. A spaceship could get to Pluto in 18 to 20 days by accelerating at 1g all the way, but reversing direction halfway between so it can come to a stop. If you don't care to come to a stop, it's only 13 days if one accelerates at 1g all the time.


And how do you plan on accelerating at 10 m/s^2 the whole way? iriomote already pointed out how absurdly large a railgun you'd need at above 200 m/s^2 acceleration. Acceleration requires fuel.

For this reason, the rest of your calculation doesn't really matter, because the thing you're calculating for is infeasible.
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Posted 2/10/17

auroraloose wrote:


iriomote wrote:

Eh, I didn't forget so much as didn't bother (in my defense, I did say I was being sloppy).


Of course - I too wouldn't bother with the relativistic effects here; I just wanted to point out that, as you didn't actually show what you did (because why would you do such a thing on an anime forum), Darkphoenix3450 wouldn't even be able to tell if you forgot about relativistic effects.



'your quite underestimating me. While yes It is not my field of expertise, I do dabble. After all I am scientist my self, and in my collage years I did find my self In the libraries bulking up on my knowledge in many fields that was not my own.' After all science is a interest of mine.
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Posted 2/10/17

Darkphoenix3450 wrote:


auroraloose wrote:


iriomote wrote:

Eh, I didn't forget so much as didn't bother (in my defense, I did say I was being sloppy).


Of course - I too wouldn't bother with the relativistic effects here; I just wanted to point out that, as you didn't actually show what you did (because why would you do such a thing on an anime forum), Darkphoenix3450 wouldn't even be able to tell if you forgot about relativistic effects.



'your quite underestimating me. While yes It is not my field of expertise, I do dabble. After all I am scientist my self, and in my collage years I did find my self In the libraries bulking up on my knowledge in many fields that was not my own.' After all science is a interest of mine.


Well, I couldn't tell whether iriomote left out the relativistic effects either; I read his description and thought it'd be very easy for him to have left that in the background without mentioning it. (Also, there'd be little reason to include them, as the correction is so small). And I'm a theoretical physicist.
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Posted 2/10/17

auroraloose wrote:

Well, I couldn't tell whether iriomote left out the relativistic effects either; I read his description and thought it'd be very easy for him to have left that in the background without mentioning it. (Also, there'd be little reason to include them, as the correction is so small). And I'm a theoretical physicist.

I'll admit I could have been less vague. I left the mathematical particulars intentionally vague since I didn't want to distract from my point with minutia.

The 50 year figure, speed required, etc. were all arbitrary. I was merely using them to illustrate just how absurdly huge a railgun would be required if you didn't want your passengers to be instantly liquefied while accelerating to the sort of speed that's useful for interstellar travel.
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