Give me another year of study, then I could do it (and know what I am doing)

Sorry

Yeah, too tough for me as well - and I won't ever even study physics...

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Ok, I feel a little better, but not much. Surely it isn't that hard.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

You should be able to calculate the fuel by using the appropriate equation twice. First, work out how much fuel will be required for the return trip (when the ship's mass is 10,000 tonnes); then work out how much fuel will be required for the first half of the journey (treating the return fuel as cargo, so that the Golightly's mass is 10,000 tonnes + mass of return fuel).

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Let's see. The return trip would have just the right amount of fuel but we must come to a stop. Therefore, if we calculate the fuel to run out at midway, then double this amount, we will have the right amount for the entire return trip. This yields 253,432 metric tonnes.

However, we had to haul this amount of fuel with us to Procyon. Therefore, the total payload to Procyon would be the 10,000 tonnes plus the return fuel of 253,400 tonnes, or, say, 263,000 tonnes. The M/m ratio for 1/4 the trip (midpoint) is 12.67, double for one way, or 25.34. This times the 263,000 tonnes yields 6.7 million tonnes of fuel needed at departure to make the entire round trip. I hope I'm wrong.

Of course, IIRC, Procyon is a binary with a white dwarf. With proper timing, and a tidally [and other stress] resistant hull and crew (), a tight turn-around at the moment the dwarf's orbital tangent points to Earth should save a few gallons.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

This intrigues me more than the fuel question. Since the time value was dilated, wouldn't that produce the distance they experienced in the relativistic time they saw (using conventional s=at^2/2)? If they saw less, or more, distance, how would they claim a 1 g acceleration?

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

So do I! Otherwise I'm wrong.

1 g is only the apparent acceleration: it's the acceleration that a non-accelerating frame of reference would measure if it was momentarily travelling as fast as the Golightly.

The equation I used was:

s_contracted = [c²/g]*[log_n(gs+c²) - 2*log_nc]

where s is the uncontracted distance.

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I wish we were; that's a lot of fuel. I'll accept your affirmation, however.

If another can run with this, please do so; for I may not be able to get back for a few days due to buisness.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

7.48 lyrs.? (4 x distance to midpoint seen by travelers per your equation, I hope)

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

That's what I got.

I think I've waited long enough. I was hoping for some more feedback because I'm not entirely confident that my answers are correct. Anyway, these are the figures I worked out (all approximate):

Total Earth-time of the Golightly's journey: 26.4 years

Total ship-time: 10.1558 years

Distance travelled as measured by the ship's crew: 7.48 light-years

Total fuel required at launch: 349 million tonnes!

I believe George has already posted his question:

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I am still curious on this, though. If they experience space coming at them at 1 g for 11.2 years (dilated time), while looking toward their destination, why would they measure less distance traversed than Newton's laws would claim. Are we suppose to double dip the dilation effects?

According to your formula, they would average .74c, whereas their tape measure results per elapsed time would average .41c (assuming my viewpoint is right, of course, though it most likely is not). Even with a contracted spacetime affecting the tape measure, wouldn't they still physically measure 13.3 lyrs. total self-measured distance traveled?

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

I derived the equation for calculating the contracted distance thus. I plotted the Gamma^-1 factor on the Y-axis against s (uncontracted distance) on the X-axis. Integrating gives the area under the graph, which is the contracted distance (I think!).

According to Relativistic Rocket, Gamma = as/c^s+1. Therefore, Gamma^-1 = c²/(as+c²). The area under the graph, then, is:

s' = c² ∫ 1/(as+c²) ds

= (c²/a)(log_n|as+c²| - 2log_nc)

The equations seem to be correct, then.

Taking just the first quarter of the ship's trip (halfway to Procyon), the stats are:

Distance (Earth): 5.7 LY
Distance (ship): 1.87 LY
Time (Earth): 6.6 years
Time (ship): 2.54 years.

I don't know that you can plug these figures into s=ut+½at², as that equation is derived from the linear function v=u+ft.

Perhaps someone else can explain how the crew can reconcile the fact that they have covered 1.87 LY in 2.54 years, reaching a speed of 0.74c, with the other fact that they can still feel an acceleration of 1.03 LY/year^-2.

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for a bonus question, quickly guessed and easily gotten (not to mention worthless in the context of this thread)



what do Polaris and Sirius have in common? besides one r?

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Some of my Astrophotography


Those that lack education have a hard time understanding its value. - Cross

Members of the same moving group?

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The both have companions brighter in the X-ray band than they are.

William Keel's (ngc3314) new book, The Sky at Einstein's Feet, shows Sirius and SiriusB and talks of this. In the visible Sirius is 10,000xs brighter than its companion.

The current question is still active....

Name a single receiver interferometer.

[hint: It was an early creation and implented by Aussies succesfully.]

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Another hint, maybe...

It involved Dover and ID. It was from Dover that the IDentity of the size of a radio galaxy was less than 8 arc seconds.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Is the question about a "single receiver interferometer"? There are several used in astronomy. Michaelson inerferometers are single receiver and have been used for IR spectroscopy (I acually help with one at Lick Observatory). I suspect what is wanted here may be a Sea Surface Reflection Interferometer.

Yes, the latter was the one I knew about. Pretty interesting technique. One was built in the 1940's .

It's now yours, IMO.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

In 1920 a "debate" over the distance scale of the universe took place at the Smithsonian in Washington. On the event of the Diamond Anniversary of this debate, another took place in the same venue with a closely related topic. Name the topics and participants of both debates.