Free planetarium

Search found 884 matches

  • 1
  • 2
  • 3
  • 4
  • 5
  • 59
by Watsisname
20 Oct 2017 01:22
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Videos
Replies: 273
Views: 13380

Science and Astronomy Videos

It seems that Nothing is popular to talk about lately. :) 14902 Watsisname, Sean Carroll covers many of the concepts you and I have discussed before in this video Yes, his talks are excellent!  I concur with his conclusions about us being products of vacuum fluctuations vs. the universe beginning in...
by Watsisname
19 Oct 2017 23:09
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Questions
Replies: 704
Views: 30807

Science and Astronomy Questions

14903 My question is, why do g-waves reach us before the visible light is detected? What is this lag time and what causes it? They were not emitted at the same time. It's a bit similar to how we receive neutrinos from a core collapse supernova before we see that the star explodes and brightens.  Th...
by Watsisname
16 Oct 2017 22:45
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy News
Replies: 351
Views: 15639

Science and Astronomy News

Almost.  I think this one still holds the record at 5154.  It's so funny to see it authored as

G. Aad et al.*     

Followed by "*Full author list given at the end of the article.", which goes for 24 pages out of the 33. 
by Watsisname
16 Oct 2017 20:31
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy News
Replies: 351
Views: 15639

Science and Astronomy News

It is an incredibly big moment for gravitational wave astronomy.  We have detected several black hole mergers already, but now for the first time we have a gravitational wave event observed coincident with electromagnetic emission.  Black hole mergers are violent events, but the violence is almost p...
by Watsisname
15 Oct 2017 23:07
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy News
Replies: 351
Views: 15639

Science and Astronomy News

Indeed.  The motivation for proposing epicycles was to explain variable and retrograde apparent motion of the planets in a way that preserves the notion that things move around the Earth in heavenly circles.  What predictive power did epicycles have which help justify the proposition?   I don't know...
by Watsisname
15 Oct 2017 20:45
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Questions
Replies: 704
Views: 30807

Science and Astronomy Questions

14681 Yes, I love math too!  Which is why I was so puzzled by it being called "gross."  I mean raw sewage is gross (or sewage of any kind)- but math?!  No! ;) https://i.imgur.com/yCX7Z5e.jpg 14681 How long will it be before we understand the details of the collapse and rotating black hole...
by Watsisname
15 Oct 2017 14:36
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy News
Replies: 351
Views: 15639

Science and Astronomy News

14774 Does anyone really categorically deny that dark energy can be described as an ad hoc hypothesis?   Even if we agree that it's ad hoc because there is still much we don't understand, that doesn't mean that it's wrong.  The question is rather whether we should shut the other doo...
by Watsisname
15 Oct 2017 07:01
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy News
Replies: 351
Views: 15639

Science and Astronomy News

Such critique of dark matter and dark energy as being ad hoc or unfalsifiable is quite common.  It  is also based on significant misconceptions. Dark energy is a name we give to the observed  accelerating expansion of the universe (measured from supernovae data).  When the cause of this acceleratio...
by Watsisname
13 Oct 2017 21:15
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Videos
Replies: 273
Views: 13380

Science and Astronomy Videos

If the numbers loop back to negative, then you haven't gone high enough. :)  To illustrate with y=tan(x), that means you stepped too far in x, and thus missed a bunch of y.  In fact you did not just miss a bunch, but an infinite amount of it. :P  Get closer and closer to that singularity, and you m...
by Watsisname
13 Oct 2017 16:32
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Videos
Replies: 273
Views: 13380

Science and Astronomy Videos

Yet multiplying zero by infinity does not yield 1.
by Watsisname
12 Oct 2017 19:16
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Questions
Replies: 704
Views: 30807

Science and Astronomy Questions

Mr. Missed Her , I'm afraid this may be disappointing, but simply using the equation for an ellipse will not help you determine the position as a function of time for an orbit, because the speed is not constant but rather must obey the vis viva equation .  In fact, there is no algebraic expression ...
by Watsisname
12 Oct 2017 17:30
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy News
Replies: 351
Views: 15639

Science and Astronomy News

14661 Since we're talking about dark energy, I've got to ask: What if we're just in a less dense region of space bigger than the observable universe? The more dense universe around our patch would be pulling everything away from our observable region, and it looks like the universe is expanding. 14...
by Watsisname
12 Oct 2017 15:37
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy Questions
Replies: 704
Views: 30807

Science and Astronomy Questions

They're very neat as mathematical entities, but that's all they are.  Ring singularities do not exist in nature, but are simply consequences of assuming the mass of a rotating black hole exists at a point to begin with.  That assumption leads to predictions that contradicts itself, and the true natu...
by Watsisname
12 Oct 2017 00:46
Forum: Science and Astronomy Discussions
Topic: Science and Astronomy News
Replies: 351
Views: 15639

Science and Astronomy News

14644 Would a plethora of tiny, moon-massed black holes effect our view of other galaxies? Perhaps surprisingly, no! To give an idea, the average mass density of dark matter in the universe equates to about 1.4 protons per cubic meter.  If it is all in the form of black holes with the mass of the M...
  • 1
  • 2
  • 3
  • 4
  • 5
  • 59