Ultimate space simulation software

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by Watsisname
17 Jul 2019 00:19
Forum: Off-topic Discussions
Topic: Tools to calc travel time and trajectory when under acceleration?
Replies: 1
Views: 111

Tools to calc travel time and trajectory when under acceleration?

This is a hard problem.  I am unaware of any tools that do this. Computing the path and travel time for a Hohmann transfer (smallest delta-v path from one orbit to another without assists) is fairly simple, as is the path under constant acceleration and the assumption that the peak velocity is high ...
by Watsisname
04 Jul 2019 02:50
Forum: Off-topic Discussions
Topic: Show off your work
Replies: 376
Views: 71071

Show off your work

Back from another mineral-hunting adventure.  This time the objective was quartz crystal. Inside a "crystal cave".  No, not a vug.  Manmade, this claustrophobia-inducing tunnel was dug beneath the stump of an old logged tree.  The whole area is a slump zone, and the roots catch crystals as...
by Watsisname
04 Jul 2019 02:10
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Questions
Replies: 1547
Views: 179563

Science and Astronomy Questions

30316 When observing a pulsar from Earth, can we determine what the angle between the rotation axis and magnetic axis is? A late answer, but the answer is yes, this can in fact be done!  The method is outlined in section 2 of the paper  On the Evolution of Pulsar Beams  by Tauris and Manchester (19...
by Watsisname
25 Jun 2019 19:15
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Questions
Replies: 1547
Views: 179563

Science and Astronomy Questions

This is a very good question.  An important combination of physics and philosophy. In my view, I think there must be the capacity to make mathematical descriptions of all physical properties. A physical property is (in principle) a measurable one.  It is some aspect of nature that is present has som...
by Watsisname
24 Jun 2019 05:09
Forum: Off-topic Discussions
Topic: Show off your work
Replies: 376
Views: 71071

Show off your work

Nice catch.  They were over here as well last week.  Saw them low in the north driving past Seattle in the morning.  Didn't get any pictures, though.
by Watsisname
20 Jun 2019 00:12
Forum: Off-topic Discussions
Topic: BREAKING: New potentially habitable exoplanet found around Teegarden's star
Replies: 10
Views: 595

BREAKING: New potentially habitable exoplanet found around Teegarden's star

30052 The exoplanet found, called Teegarden b, has a minimum mass almost identical to Earth. I hate to dim the excitement, but I think that this part is important to emphasize.  When detecting an exoplanet by radial velocity measurements, the strength of the signal (how much it tugs its host st...
by Watsisname
17 Jun 2019 16:39
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Videos
Replies: 426
Views: 59636

Science and Astronomy Videos

PBS Space Time's latest video on how supermassive black holes extend their influence on and even beyond their host galaxies, to have far-reaching consequences on star formation.  It's also a nice review of the M-sigma relation (the surprising connection between the mass of the black hole and its hos...
by Watsisname
16 Jun 2019 00:39
Forum: Science and Astronomy Discussions
Topic: Astrophotography
Replies: 325
Views: 46183

Astrophotography

Those are seriously impressive!  I feel like these could be photos from an Apollo mission.  The focus and atmospheric turbulence look perfect on the second shot, which supports the sharpening. :) 
by Watsisname
16 Jun 2019 00:30
Forum: Space Journeys
Topic: Planets with potentially breathable atmospheres
Replies: 358
Views: 57585

Planets with potentially breathable atmospheres

JKerman, looks good to me!  Nice find. :)
by Watsisname
12 Jun 2019 19:38
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Questions
Replies: 1547
Views: 179563

Science and Astronomy Questions

29697 but I am having trouble with the whole thing about "the universe not filling in originally empty space as it expands", mainly because you didn't state why "the universe doesn't rearrange the distribution of internal energy or matter". You're not alone with having trouble w...
by Watsisname
11 Jun 2019 22:06
Forum: Off-topic Discussions
Topic: Show off your work
Replies: 376
Views: 71071

Show off your work

Giving hard rock mining a try.  There's a marvelous spot hidden up in the hills nearby where veins of blue translucent agate/chalcedony run through volcanic rock that's tough as nails.  It's some of the most intense color I've ever seen in a stone. I spent a good portion of a day working at it with ...
by Watsisname
11 Jun 2019 15:39
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Questions
Replies: 1547
Views: 179563

Science and Astronomy Questions

29525 How do irreversible processes relate to entropy on a microscopic scale? I'm having trouble visualizing this on a universal scale. Irreversible processes involve changes that can't be undone (go in reverse) as easily as they happened forwards, which is equivalent to saying that they increase t...
by Watsisname
09 Jun 2019 15:21
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Questions
Replies: 1547
Views: 179563

Science and Astronomy Questions

29498 so the amount of entropy can be measured by calculating the volume of a system Not necessarily, and in fact this doesn't work with the expansion of the universe.  Let's look in a bit more detail.  In some cases, such as gas expanding to fill its container, it is true that the expansion is ass...
by Watsisname
08 Jun 2019 19:57
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Questions
Replies: 1547
Views: 179563

Science and Astronomy Questions

29483 Just after a Big Bang. The universe is very small and hot. It would reach thermodynamic equilibrium long long before today. Aye, it was very hot and dense and low in entropy.  But it was also expanding very rapidly.  That expansion combined with gravity are what we need to think about here. T...
by Watsisname
08 Jun 2019 15:59
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Questions
Replies: 1547
Views: 179563

Science and Astronomy Questions

29446 Entropy in a system will always increase, as per the Second Law of Thermodynamics. Increasing entropy overtime in a system is the natural result of that system existing. Entropy of a closed system can also be constant.  Example:  An expanding universe filled with photons is isentropic,  or ha...