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Episode 4 "A Sky Full of Ghosts"
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3/29/2014 at 10:18:04 PM GMT
Posts: 130
Episode 4 "A Sky Full of Ghosts"
This topic is devoted to episode 4 of Cosmos: A Spacetime Odyssey


Last edited Sunday, May 11, 2014
3/31/2014 at 2:20:22 AM GMT
Posts: 41
A Cosmological Cosmos

This is more what I expected from the Cosmos series – cosmology and some astrophysics, e.g., black holes with the mass of 4,000,000 suns and what it might be like to approach the event horizon of one.

While I appreciated the point they were making, I don’t know how helpful it is to say that the, “Sun’s image is an unreal ghost because the light we see from it is 8 minutes behind and by the time we “see” it the Sun is no longer in that relative position off the horizon. 

The same could be said about any image we see – what we see is a ghost of what we were looking at because the light isn't instantaneous.  The only difference is that close objects like we see on earth might as well be instantaneous because that light and the object producing the image are essentially in sync for almost all intents and purposes.  The moon is about 1 light-second away.  So, where do we draw the line?  However, I suppose if you ever thought of visiting some distant star or galaxy, even if you could get there instantly, better guess again, because it wouldn’t still be in that location or may not still exist at all.  We could say that we’ll cross that bridge when we get to it. 

But, I understand that GPS triangulation works by taking advantage of this phenomenon.

I noted Tyson said we couldn't see any objects further away than the light from the crab nebula 6,500 light years away if the earth was only 6,500 years old.  Good point. 

It’s interesting how they said that they don’t know what happened before the Big Bang but they do have some “crazy ideas” about that.  That might have been a phrase I would have used, especially since I'm not an astrophysicist and tend to think the gap between what we can know about that and what science can answer is perhaps getting wider rather than being filled by science. But, I'm surprised to here Tyson put it that way.  Thoughts?



Last edited Sunday, March 30, 2014
3/31/2014 at 8:52:21 AM GMT
Posts: 21
I looked at an article someone posted a link for about the hubbub about multiple universes last week. The link promised "why we think there are multiple universes." There wasn't a word in the article about why, only a description with some graphics and really big numbers. The phrase from the old '60s song came to me, "Don't ever ask them why, if they told you, you would cry." Cry in this case, because if the physicists told you why, you wouldn't a clue what they were talking about. They spin wild tales based on arcane mathematics, with no possibility of confirming evidence. Only a handful of people in the world are equiped to think critically about it. What can I, a mere biochemist, do, but smile, pat them on the head and go think about molecules that I can actually measure.


3/31/2014 at 10:57:43 AM GMT
Posts: 130
Once again, graphics outshone the content. It's fun to watch, though it isn't always easy to recognize what the graphics are showing. I felt that Tyson missed a great chance to explain how we know the distance and age of celestial objects. He just seemed to assert that this is true and if the universe were only 6-10,000 years old, we wouldn't be seeing most of the stars and galaxies. Apparently, he hasn't studied much YEC literature on the topic.
When it came to relativity, it was rather creative to show a woman driving a motorcycle at nearly the speed of light, but he again missed a chance to talk about space contraction and time dilation at those speeds.
The discussion of black holes and of their possible relationship to alternate universes was more interesting, though again a bit short on how we know it. Mainly, he showed William Herschel telling his son, John, that we know it just like we know a person made footprints in the sand. For black holes, those footprints, he said, were the X-rays radiating out from material falling into the black hole. He asserted that within the black hole could be an entire other universe. Maybe. Or maybe not.
I'm not a historian of science so I can't assess that aspect of the series, but I do appreciate learning more about some of the less well-known practitioners of science like Halley last week and Herschel this week.
Keith, as for the phrase "before the Big Bang" and "crazy ideas," it's pretty hard for any of us to talk about what existed or what happened before time began. It really does seem to be "crazy" especially when it's beyond the event horizon where we have any possibility of knowing. But it's still fun to speculate and maybe some day these "crazy" ideas will lead to something that isn't quite so crazy any more.


3/31/2014 at 6:39:10 PM GMT
Posts: 12
All Flash and No Fire?
@Keith
Did Tyson actually say that "if the earth was only 6500 years old, we would be unable to see out to anything beyond 6500 light-years distant"? - I hope he actually meant that if the 'universe was only 6500 years old' :)  I caught that remark, and although I agree with the thrust of Tyson's point, I did think it was a needless dig at YEC - he just had to get in that remark.

My biggest complaint with the series thus far echoes what Randy said - impressive graphics, shallow content - is this what we can expect for the entire series - missed opportunities to elaborate on real science? Perhaps because we are professional scientists we see what is missing, so we are evaluating the series with a more critical eye than a lay audience would.

Victoria



Last edited Monday, March 31, 2014
3/31/2014 at 7:28:31 PM GMT
Posts: 8
I agree with the comments about graphics & special effects. Sagan was lucky that the technology for those things wasn't so well developed ~30 years ago so didn't get as distracted by them.

Last night's episode was rather choppy & in some ways inaccurate. Tyson was going to describe how the young Einstein, in that setting in northern Italy, came up with the idea that would lead him to special relativity. Unfortunately he never quite did that. As Einstein described it later, he thought about what he'd see if he could match speeds with a light wave, and realized that it would be electric and magnetic fields oscillating in place at right angles with one another. Since he knew that Maxwell's equations didn't have such a solution, there had to be a problem with the idea that one could travel at the speed of light. Tyson doesn't describe it that way, & couldn't because then he would have had to spend some time on what Maxwell's equations are. & this is a problem that a lot of popularizations of relativity & quantum theory have - they try to take short cuts to the gee-whiz stuff without their audience having any grounding in basic classical physics.


3/31/2014 at 8:01:10 PM GMT
Posts: 51
The series is still enjoyable for me. The graphics are very nice and I especially liked all the galaxy artwork.
The horizon analogy, showing us how each observer will see them self as being at the center of the universe, was one I had not seen before. I still favor the stretching balloon analogy, though they did not present it.

Their efforts to credit Herschel were nice, but I kept expecting they would show his homemade giant telescope, or tell us of how is wife and others assisted his great work. Then there was that great discovery of his of the first planet ever discovered in recorded history, which he named “George” (Georgium Sidus; “George’s Star” for King George)– one of my favorite astronomical stores for some reason. "Uranus" would not have been my second choice, nor that of most science teachers.

The account of how Herschel was the “first” to realize that we were looking back in time may be true given his prestige, yet it seems a little dubious. It was Ole Roemer who, 106 years earlier, demonstrated that light does not travel instantaneously. Roemer, admittedly, did not state the speed for light since he did not know Earth’s orbital distance. Perhaps his work simply was not appreciated until more supporting evidence (e.g. stellar aberration) came along. Nevertheless, it was clear from Roemer that it takes time for us to see distant things.

I liked the way they showed the importance of indirect evidence in their black hole example of Cygnus X1.  The red accretion disk formed from the loss of atmosphere from the orbiting binary partner could have been a little better since I doubt these disks appear red, and the x-rays mentioned are seen at or near the feed point upon the accretion disk. A very bright spot would have been a great touch of what we see. There is a chance I have this wrong, but it is only a nit.

Thereafter on the black hole subject, they spent an inordinate amount of time on the wild speculations about time and space often associated with black holes including pathways into, possibly, other universes. I kept thinking they would show how anyone entering a black hole would be, as even Tyson has written, “spaghettified”, where the tidal force difference over a few feet is enough to rip the body into shreds as it gets close to the event horizon of a normal-sized black hole. Ironically, with a supermassive black hole, one can slip inside without this problem since the gravitational gradient is less intense because its event horizon is so far away from the center.

I wonder if it is correct to state that from the event horizon we could see the future history of the universe unfold before our eyes. It may be true that observers from afar would see objects frozen in time at the event horizon, but the traveler would continue onward, apparently to all those wonderful places beyond, including someone’s parking lot. Bon voyage, or are we really already there? Why not spend more time on real science and not so much on pseudoscience?


Last edited Monday, March 31, 2014
3/31/2014 at 11:53:35 PM GMT
Posts: 19
George (Cooper)

I think you make a good point about the black hole segment. After all, if we can speculate about the possibility of universes inside black holes (inside universes etc, so turtles all the way) what is to stop us from speculating that some black hole might contain Heaven or Hell? Perhaps that parking lot Tyson showed is actually Hell, where one must search for a parking space for eternity.


4/1/2014 at 2:02:19 PM GMT
Posts: 51
Sy

Yes, they should be a little more uncomfortable with all those turtles. :) Perhaps there is a rabbit metaphor as well. How does one avoid a theological rabbit? Make its hole infinite.



4/2/2014 at 6:03:23 PM GMT
Posts: 41
Victoria,

Yeah, I don't know if he said "Earth" or "Universe" but Earth would have been the point of reference for seeing beyond 6500 light years in that Universe, and yes it would be the Universe too that would have to be older.

Tyson elaborates on why he did that here in this Huffington Post article, Neil deGrasse Tyson Blasts Creationism In New 'Cosmos' Episode Tweeted on our ASA site.

Randy,

Good perspective on "crazy ideas".  Also, I thought I saw briefly in Episode 3 where Tyson described how we know that Earth is 93 million miles from the Sun via triangulation or some other math but I was a little distracted at the moment and didn't catch it clearly.  Anyone else catch the details?  Regardless, he missed a chance to drive that home when he talked about the 6500 light years and not being able to see beyond the Crab Nebula.  Combined, I think it makes another really good argument against a young earth.

What about god-of-the-gaps argument when the gaps are getting bigger rather than smaller?

Denis Lamoureux puts forth the idea in his course or one of his lectures that, while its not a good idea to make god-of-the-gaps arguments (inserted God into gaps in our scientific knowledge) when those gaps are continually being filled with increasing scientific knowledge, if you're going look for such arguments then look were the gaps in our scientific knowledge are getting bigger.

I alluded to that in my post above and thought it would be interesting to tease that out a little more and hear what others think.  Is that what is happening regarding the question, "What happened before the Big Bang?", and those "crazy ideas"?

Science has answered so many questions in the last century that we should be a little gun-shy of making any attempts to challenge what it can or cannot tell us about our material existence.  But, there are several considerations that suggest science has hit a wall on that one beyond which it cannot go inasmuch as it is limited to investigating the material world and its laws.  

  1. Tyson mentioned that black holes could be the source of another universe. But, isn't that a recapitulation of the oscillating universe hypothesis that is at least no longer in vogue?
  2. Time and space had a beginning -- regardless of oscillating (even if) or however it happened, they say any way you do the math, time and space had to have a beginning.  That's according to work of some top physicists in 2012, I believe. See http://www.technologyreview.com/view/427722/mathematics-of-eternity-prove-the-universe-must-have-had-a-beginning/
    • I've read somewhere that atheist physicist Vic Stenger counters that it was so long ago that it might as well have been eternal. But, to God, who is above and/or transcends time and space, almost eternity is no time at all and doesn't count, in my book. If it had a beginning, it had a beginning. But, I'm sure Stenger and other won't let it rest there.
  3. What if the "crazy ideas" aren't testable ideas?
  4. Maybe its because I'm an armchair physicist, at best, but I still don't see how even those "crazy idea" explain how there was something (even physical laws, etc.) to go bang since empty space isn't empty (has vacuum energy and physical laws, etc.) and can't be the "nothing" we are talking about when we say, "out of nothing", and before time & space there wasn't even space.
I'm no longer out to use science to prove God (don't believe God intends to be proved or our faith would be sight) but tend think of such things with caution optimism as pointers to God or at least ways that I can find understandable to see God's action in Creation.

I did think it was humble of Tyson to refer to those pre-Big Bang ideas as "crazy ideas".