How to calculate in-system travel times easily

[GypsyComet]

Seems to me 7 days of 1g acceleration is all you need to get anywhere in the Solar System. if you have an FTL Jump Drive, you have no need to get anywhere near the speed of light either.

This is often a lost point. Even 1G is a lot of acceleration, allowing essentially straight-line travel between any two points in a system that don't have the star between them.

That said, two weeks of fuel is still a bit stingy.

 

[GypsyComet]

Making personal attacks against those people doesn't make you any better than they are.

I'll note that some boards consider your earlier post toward him a banning offense, so let's leave the stone throwing where it sits.

 

[sideranautae]

Cite please. As far as I'm aware, time dilation occurs for things travelling near the speed of light - their acceleration isn't what slows it down, it's their velocity.

I think you're confusing this with something else - maybe you're thinking of frame-dragging or something?

You can google it. I don't bookmark everything I read. It came out over a year ago. I'm not confusing it with anything else (I was very attentive when I read it over). It is basically gravitational time dilation. It was theorized but recently thoroughly tested with two objects traveling at the same speed but under different gravitic acceleration.

 

[sideranautae]

Seems to me 7 days of 1g acceleration is all you need to get anywhere in the Solar System. if you have an FTL Jump Drive, you have no need to get anywhere near the speed of light either.

Earth to Neptune, when at their closest would take about 15 days at 1 G. If on the opposite sides of the sun, even longer.

 

[Wil Mireu]

I'll note that some boards consider your earlier post toward him a banning offense, so let's leave the stone throwing where it sits.

How about we just stick to the topic of the thread and spare the personal judgements?

 

[Wil Mireu]

You can google it. I don't bookmark everything I read. It came out over a year ago. I'm not confusing it with anything else (I was very attentive when I read it over). It is basically gravitational time dilation. It was theorized but recently thoroughly tested with two objects traveling at the same speed but under different gravitic acceleration.

Huh. Well, that's just wacky.
http://en.wikipedia.org/wiki/Gravitational_time_dilation

 

[Rick]

Cite please. As far as I'm aware, time dilation occurs for things travelling near the speed of light - their acceleration isn't what slows it down, it's their velocity.

I think you're confusing this with something else - maybe you're thinking of frame-dragging or something?

You can google it. It came out over a year ago. I'm not confusing it with anything else. It is gravitational time dilation. It was theorized but recently thoroughly tested. Two objects traveling at the same speed but under different acceleration.

Both velocity and gravity slow down time as they increase. I know - it's a mind boggler.

 

[GypsyComet]

Seems to me 7 days of 1g acceleration is all you need to get anywhere in the Solar System. if you have an FTL Jump Drive, you have no need to get anywhere near the speed of light either.

Earth to Neptune, when at their closest would take about 15 days at 1 G. If on the opposite sides of the sun, even longer.

Though not four times as long, as one old calculation suggested. That's a 28AU trip at closest approach, and 31 AU or so at furthest, stretched slightly by needing to go around the Sun. You would need to get around the Sun with a jump, too, assuming you subscribe to Jump Shadows.

 

[sideranautae]

You can google it. I don't bookmark everything I read. It came out over a year ago. I'm not confusing it with anything else (I was very attentive when I read it over). It is basically gravitational time dilation. It was theorized but recently thoroughly tested with two objects traveling at the same speed but under different gravitic acceleration.

Huh. Well, that's just wacky.
http://en.wikipedia.org/wiki/Gravitational_time_dilation

Very interesting stuff. My physics foo really only goes to the basics but I still enjoy reading about it.

Also, here's a website with some handy tools for Trav players:
http://www.transhuman.talktalk.net/iw/traveller.html

 

[dragoner]

Both velocity and gravity slow down time as they increase. I know - it's a mind boggler.

Yes, and in a frame of reference so that the passage of time will be perceived differently.

 

[Tom Kalbfus]

Seems to me 7 days of 1g acceleration is all you need to get anywhere in the Solar System. if you have an FTL Jump Drive, you have no need to get anywhere near the speed of light either.

Earth to Neptune, when at their closest would take about 15 days at 1 G. If on the opposite sides of the sun, even longer.

Seems to me that anything that would take longer to reach than a Jump Drive would, one should use the jump drive for. After all time is money!

 

[Tom Kalbfus]

Both velocity and gravity slow down time as they increase. I know - it's a mind boggler.

Yes, and in a frame of reference so that the passage of time will be perceived differently.

You don't get any significant time dilatation until you exceed 72% of the speed of light, in any campaign with Jump Drive technology, this would be rarely done. This doesn't come p in in-system travel.

 

[Wil Mireu]

Seems to me that anything that would take longer to reach than a Jump Drive would, one should use the jump drive for. After all time is money!

Yes, if travel takes longer than a week - assuming the ship is equipped with a jump drive - it makes more sense to use that to get somewhere that far away instead. There is a precedence for in-system 'microjumps' in Traveller too.

Though yes, jump shadows may be a problem if the destination is on the other side of the sun.

 

[sideranautae]

Seems to me 7 days of 1g acceleration is all you need to get anywhere in the Solar System. if you have an FTL Jump Drive, you have no need to get anywhere near the speed of light either.

Earth to Neptune, when at their closest would take about 15 days at 1 G. If on the opposite sides of the sun, even longer.

Seems to me that anything that would take longer to reach than a Jump Drive would, one should use the jump drive for. After all time is money!

Only HUGE slow possibly unmanned freighters would not use jump. Or, as Will points out, if the star shadows the destination.

 

[GypsyComet]

Earth to Neptune, when at their closest would take about 15 days at 1 G. If on the opposite sides of the sun, even longer.

Seems to me that anything that would take longer to reach than a Jump Drive would, one should use the jump drive for. After all time is money!

Only HUGE slow possibly unmanned freighters would not use jump. Or, as Will points out, if the star shadows the destination.

The one other case would be where fuel is in short supply at the destination, so showing up with empty tanks is problematic. Granted, most civilized destinations won't have this problem, but since when do adventures always take place in civilized locations? A four week round trip is preferable to one week out and not coming back...

 

[sideranautae]

Only HUGE slow possibly unmanned freighters would not use jump. Or, as Will points out, if the star shadows the destination.

The one other case would be where fuel is in short supply at the destination, so showing up with empty tanks is problematic. Granted, most civilized destinations won't have this problem, but since when do adventures always take place in civilized locations? A four week round trip is preferable to one week out and not coming back...

There is that. A salvage Op not near a refueling source.

 

[dragoner]

You don't get any significant time dilatation until you exceed 72% of the speed of light...

What?

 

[Wil Mireu]

You don't get any significant time dilatation until you exceed 72% of the speed of light...

What?

Are you having trouble reading?

He's right, pretty much. http://en.wikipedia.org/wiki/Time_dilation#Overview_of_formulae

The time dilation factor is gamma (the Lorentz factor). At 0.7c, it's a factor of 1.4 - at that speed means time runs 1.4 times more slowly as measured on the ship than as measured by an outside observer. At 0.866c, gamma = 2.00. You only get really big time dilation (gamma > 10) really close to c (0.99c or more) - see the chart at http://en.wikipedia.org/wiki/Lorentz_factor#Numerical_values

 

[sideranautae]

Here is a Relativistic Star Ship Calculator

 

[dragoner]

He's right, pretty much.

No.

atomic clocks at differing altitudes (and thus different gravitational potential) will eventually show different times.

Difference being is that I know this stuff.