Relativity calculator for interstellar journeys

[Vertigo]

I couldn't find what I wanted so I wrote my own and thought I'd make it available for anyone interested. I'm not after money so it is absolutely free! (and has no nasty ads, spyware, popups etc.)

The basic idea is a relatively (sorry!) simple calculator that will let you calculate interstellar journey times for starships travelling close to the speed of light. It will tell you how much time has elapsed in the universe and how much (little?) time has elapsed for the crew of the ship.

Your journey can be in multiple stages so for examples a two stage journey might start at rest and accelerate until the midpoint (stage 1) and then decelerate back to rest (stage 2). A three stage journey might have a "coasting" stage in the middle with zero acceleration.

You can download it here: http://www.focussoftware.co.uk/downloads/StarTraveller_Setup.exe
(I haven't bothered to create a web page for it so that is a direct link to the setup program).

Here's a couple of screenshots to give you an idea of what it looks like one is just the raw calculator for working out a stage and the other is a graphical representation of the whole journey. The vertical axis is velocity (both proper and map) and the horizontal axis is distance (with optional superimposed axes for map time and traveller time).

 

[Parson]

Ohhh! I now have an answer for who put the science in Science Fiction. Good Work!!

 

[alchemist]

I posted in the other thread that I couldn't follow the links, but this appears to be working fine. I'm sure you've taken into account the recent news that all that Einsteinian stuff is bunkum now?

Thanks, Vertigo.

 

[Vertigo]

Thought I'd stick with this thread

I'm planning on asking on a couple of Science sites if they can check whether the results are correct. They seem reasonably sensible giving the sort of results I would expect but some of the equations bomb out on negative accelerations (devide by zero, sqare roots of negative numbers etc.) requiring me (in my absence of real knowledge) to be a little inventive for those situations. However I now think it is working correctly!

I've not done anything as sophisticated as putting together any help, but please feel free to ask here and I'll answer as best I can!

 

[JAJackson]

WOW Nice - It took me WEEKS to come up with a working formula !!!! I never thought to 'Software' it, and damn I was in the IT industry for many years. WOW again.

 

[Interference]

Excellent piece of creativity, Vertigo, your place in history is assured.

 

[Vertigo]

Thanks for the comments!

I have done some more work on this but to be honest I've not had the time to do as much as I wanted and haven't bothered to upload a new set up. If anyone is interested then I will do so. It has some small bug fixes and it also has a sort of journey wizard for auto building two stage (acceleration and deceleration) and three stage (acceleration, coasting and deceleration) journeys.

 

[TheTomG]

That's a brilliant idea Vertigo! Downloading now. I actually have a story where this could be useful for me too.

 

[alchemist]

I'd be interested in the 2 and 3 stage model too, Vertigo. I think your programme really fills a gap.

 

[Abernovo]

I'd definitely be interested in the 2 and 3 stage as well, Vertigo. My only problem at the minute is what size is it. My connection is so slow at the moment that I can't download much at all. It's even struggling with the Chrons some of the time.

Hopefully, if you add your modifications, I'll be able to download it. I had to sit and work travel stages out recently, using a calculator and notation. Anything to save doing that again would be much appreciated.

 

[Vertigo]

Abernovo it is less than 2M so really not very big.

Since there seems to be some interest (thanks for the comments) I have just uploaded a new version. For the automatic 2/3 stage calculator use the Auto New button. The download link remains the same:

You can download it here: http://www.focussoftware.co.uk/downloads/StarTraveller_Setup.exe
(I haven't bothered to create a web page for it so that is a direct link to the setup program).

As I said before there is no help so if you have any queries, just ask them here and I'll do my best to answer. Please bear in mind that this is something I knocked up for myself so it's not very polished . The best way to view and edit stages is to go to the Journey Chart. It really doesn't need the two windows and it would be better if everything was in just the one. However it was initially just a calculator and the chart was added later so it didn't end up as seamless as it probably should!

If I can ever find time I want to try and add some sort of "sub-stages"; the idea being if you release some sort of drone (or whatever) whilst you are decelerating so that it will continue at the speed it was released (seems like a sensible time to do something like this would be at turn around ie. at max speed). Then be able to view where the probe will be relative to the original ship as you decelerate.

 

[Vertigo]

By the way (and sorry for the double post but 'tis a slightly different subject) if you are playing with this tool here is an interesting aspect of relativity that you can look at.

Set up a three stage journey that has you approaching the speed of light and then coasting for a good proportion of the journey (make it a relatively long journey; say 40 odd light years). Take a look at how long the journey takes in both map (universe) time and how long it takes for the traveller.

Now set up the same journey but this time only two stages so you keep on accelerating all the way to the half way point. Because you were already nearly at the speed of light in the previous coasting stage the additional acceleration will make very little difference to the journey map time (from the point of view of the universe) because the additional acceleration has made little difference to your proper velocity.

So it would appear to be a waste of energy to maintain the acceleration in this way.

However now take a look at the traveller time and you will see that it has made a significant to difference to that. The reason is that you are actually still accelerating at the same rate as before but as you can't get past the speed of light the acceleration is "soaked up" by significantly increasing the time dilation. Resulting in the apparent journey time for the traveller being significantly reduced.

So if you have the resources to continue accelerating throughout the journey (eg a ram scoop type of drive that doesn't require you to carry massive amounts of fuel) then although it doesn't make the journey much shorter to the outside world it will make it much shorter for the traveller! So worth doing. I have found you can half your traveller journey time whilst making almost no difference to the universe map journey time.

 

[thaddeus6th]

Writing sci-fi isn't my thing, but this is a brilliant tool for anyone into writing sci-fi books (and possibly games as well). Kudos, Vertigo.

 

[Vertigo]

Thanks Tahddeus! And that's pretty much exactly why I wrote it, but I haven't the time to turn it into a commercial product and besides it's only a small thing, so 'tis nice to just give it away

Oh one little thing:

Abernovo, if you did these calculations recently by hand it would be interesting to compare the answers you got with what my program produces. One of the things I failed to find were any decent validated examples that I could check my results against.

 

[alchemist]

If I can ever find time I want to try and add some sort of "sub-stages"; the idea being if you release some sort of drone (or whatever) whilst you are decelerating so that it will continue at the speed it was released (seems like a sensible time to do something like this would be at turn around ie. at max speed). Then be able to view where the probe will be relative to the original ship as you decelerate.

Appropriately enough, my prologue starts with the data from just such a probe returning to the ship in-transit.

I entered one set of data and it looked good. I'll play around with it in time.

Seriously, Vertigo -- this deserves more credit. I wonder could it draw some footfall to the Chrons and would Brian be interested in promoting it?

 

[Vertigo]

Well I did mention it's existence to a couple of sites that have some of this kind of thing like Atomic Rocket ( http://www.projectrho.com/rocket/index.php ) but got little interest. However I would have no problem with Brian doing something like promoting it if he was interested. However consider also the possibility that Brian (and the mods) may specifically not want that sort of traffic.

Appropriately enough, my prologue starts with the data from just such a probe returning to the ship in-transit.

Yeah I've often thought it seems such an obvious way to do it but I've rarely encountered it being done in SF books. Actually the story that started me off down this route may start with the launch of such a probe Although I may go back a little earlier.

And I've actually stumbled on another bug tonight. I think it is a rule of software that as soon as you've launched a new release you will find an error! I'll try and get a fix up tomorrow morning.

I entered one set of data and it looked good. I'll play around with it in time.

Thanks for that; good to know!

 

[Abernovo]

Oh one little thing:

Abernovo, if you did these calculations recently by hand it would be interesting to compare the answers you got with what my program produces. One of the things I failed to find were any decent validated examples that I could check my results against.

I no longer have my workings and I'm still playing around with your programme (it's excellent, by the way, thank you) to finesse the minutiae of the trip, but it's producing figures close to those that I worked out by hand.

The difference is that your programe makes it much easier to factor in acceleration and deceleration, which I did have problems with - those blessed curves which determine whether or not the contents/passengers are crushed like bugs inside the vessel.

I'm getting figures of 305 years compared to my own original figures of 303, which I think is pretty close - <1%. I'm presently clapping myself on the back for not being so useless at maths, after all (bear in mind, I'm a lowly environmental scientist who only scraped through on the statistics modules at uni). The time relevant to traveller is also coming out to within a few months of my own figures and, with Star Traveller, I can play around a lot more with different numbers.

The fact is that the voyage is not in itself relevant to my story (which concerns events after the trip), but I needed figures to be accurate about the times and distances involved, which are relevant. So, once again, a big thank you.

 

[Vertigo]

New version released which fixes a bug that was somtimes preventing subsequent stages from being updated after an earlier stages had been modified.

The difference is that your programe makes it much easier to factor in acceleration and deceleration, which I did have problems with - those blessed curves which determine whether or not the contents/passengers are crushed like bugs inside the vessel.

This was essentially the motivation to writing the program. I can work these things out by hand, sure, but that was so slow when you wanted to play around with "what if's".

 

[Jacob Larch]

Like this a lot! Definitely a missing aspect of science fiction for writers who wish to ground their work in reality.

 

[Vertigo]

Thank you Jacob! Please feel free to pass it around!

There are some other things I want to do with it but I just haven't had the time to work on it recently

I have actually been thinking of another a simple formula calculator. By that I don't mean a 2 x 3 = 6 type of thing but rather one that calculate all sorts of general formulae for stuff like: area, volume, force, mass, acceleration, velocity etc.

Many will be easy and familiar but this is just to make them quicker so that you don't have to rearrange them for different unknowns. So for example most would know that final velocity from time, initial velocity and acceleration are related by:

Vf = at + Vo

But it's a little more of a pain to then figure that:

t = (Vf - Vo) / a

Not much I admit but then what about distance covered etc.

It would also have conversions for lots of different units in it.