Print Page   |   Contact Us   |   Sign In   |   Join ASA or sign up
Sign In


Forgot your password?

Haven't registered yet?

Calendar

11/20/2014 » 12/14/2014
The de Chardin Project, Toronto, ON

1/7/2015 » 1/9/2015
“Science and Religion in the Local Church,” Cambridge, England

1/13/2015
“Identity, self-esteem and the Image of God,” Cambridge, England

1/17/2015
Agriculture: Science & Christian Ethics, Paris, France

2/7/2015
2015 Winter Day Conference - So Calif Christians in Science

Episode 6 "Deeper, Deeper, Deeper, Still"
Moderator(s):
1
| 2
>
>|
Thread Actions

4/14/2014 at 1:29:29 AM GMT
Posts: 130
Episode 6 "Deeper, Deeper, Deeper, Still"
This topic is devoted to episode 6 of Cosmos: A Spacetime Odyssey


Last edited Sunday, May 11, 2014
4/14/2014 at 2:21:09 AM GMT
Posts: 130
Now that was quite a potpourri of mini-science lessons. I couldn't figure out the connection between them all or the storyline he was following, but they were all interesting. The most disappointing one was the photosynthesis illustration. What a Rube Goldberg-looking morass of machinery! It was hard to figure out what was doing what. That is such a vital process I would have loved to see a better description of it.

As before, many of the other illustrations got lost in their graphical depictions. The electron tracks are still showing a Bohr atom rather than the more realistic quantum version but there's probably no better way to do it.

But in the end, one does gain an awe-inspiring vision of the vastness of the universe, at both extremes of the dimensional scale. Indeed, physics is fun...


4/14/2014 at 3:19:58 AM GMT
Posts: 41
Zoom in/out From Strings to Universe
Randy, I thought the same, almost exactly.  While the 3D graphics of the mechanical illustrations were impressive, the actual protein-mediated photosynthetic reactions and trans-membrane electrical potential formation during photophosphorylation are even more fascinating.  Understanding that takes more than an hour and maybe the best way to get across the wonder of it all to kids in about 30 seconds was they way they chose.  I just wish they had shown the realistic equivalent depiction too even if they didn't take time to explain it all.

I do find the cosmic calendar use very helpful and I'm glad they keep going back to that.

But, when similarly going from the very large to very small, it seems they could get it across better with a tool like this Flash-based interactive http://htwins.net/scale2/ or a 3D animation that looks like this. Randy, this is the same one we talked about a couple weeks ago.

For those who haven't seen it, note that, using the slider after clicking Start, you can zoom all the way down to hypothetical strings and all the way out to the whole universe.  You can also click on each individual items show, to get more information about each one.  Cool.


Last edited Sunday, April 13, 2014
4/14/2014 at 3:50:41 PM GMT
Posts: 8
I agree - I thought it was all over the place. OK, I guess there was a general theme of exploring the basic constituents of matter, But if that was the point, why leave it at a 1950s level? & saying that neutrons "hold the nucleus together" was rather misleading.

While Democritus should get a nod of recognition, picturing him as a "scientist" in anything like the modern sense is questionable. The atomic theory of the Greeks was primarily philosophical speculation.

Unless there's been some radical change in our understanding of the structure of the sun and radiative transfer since I last taught astrophysics 30 years ago, Tyson was wrong in saying that it takes a million years for a photon to get from the core of the sun to the surface. It's more like ten thousand.

All in all, not Tyson's best effort.





4/14/2014 at 4:53:10 PM GMT
Posts: 51
Even more dazzling were their graphical wizardry in this episode. Excellent eye candy! Nevertheless, the “Rube-Goldberg”, as you appropriately saw it Randy, was overdone for me as well, and to the point I lost interest in what they were trying to teach with it. Perhaps it’s my age and I‘m more easily complexed with that much razzle dazzle.

They did make many great points throughout the show. The presentation of the Morgan’s Sphinx Moth was a great example case of how a theory, like Darwin’s, makes predictions that either strengthen or damage a theory. I am a little disappointed they have not taken the time to articulate just what a theory is. Prediction is not just a side benefit, but a requirement including one that allows falsification of the theory itself. This objective nature of a theory gives it its strength. But with strength comes weakness. Scientific theories fail with subjective-based areas such as art, love and spirit.

On that note, though subtle, their atheistic tone is interwoven throughout each episode. In this episode, it was first stated that we are made of atoms. But shortly thereafter, it was stated that “We are a collection of atoms.” How can we ignore that we are far more than the temple that houses us? Even love and laughter were more than implied to be part of an atomic narrative. Is not the scene using the empty cathedral but a metaphor of what seems to be a rather hollow viewpoint of who we are? I hope this changes in subsequent episodes but I would bet otherwise.

On a lighter note and speaking of betting, as ASA’s only heliochromologist, our white-only Sun was shown in order of appearance: red, orange, reddish with yellow regions added, red, brownish red, yellow in the face of Ra, and finally pink. [I don’t count the horribly glaring whitish Sun shown with Tyson in the foreground.] Also, the red color chosen for the wall of light representing the Big Bang light propagation (i.e. Recombination ) after 380,000 years post Bang was also wrong since its blackbody temperature was around 3,000 kelvins, hotter than a tungsten filament in an incandescent light bulb, thus not red, though maybe a tint of yellow in a blinding white universe.

George, the time for the core-generated photons to reach the surface (i.e. Random Walk) is often stated in millions of years. There was a paper that, as I recall, showed it was 18,000 years but they used a fixed density for the Sun, though I don’t follow this much, admittedly. So you may be right.

I’m still enjoying the show and I sure like Tyson’s delivery and style


Last edited Monday, April 14, 2014
4/14/2014 at 7:11:54 PM GMT
Posts: 51
Tomorrow morning's eclipse note:

For those who get up very early to see the eclipse but suffer from clouds, there is a Live Feed of the event, apparently, from Slooh.




Last edited Monday, April 14, 2014
4/14/2014 at 7:29:49 PM GMT
Posts: 19
I agree with all that's been said, so I wont belabor it. But I did notice something that relates to a comment Randy made. Im not sure if I am correct about this, but I cant remember there being any mention of quantum theory in any part of this series. Perhaps it will come later. But it would have been useful to help in the explanation of photosynthesis, which is apparently (according to some recent research) heavily dependent on quantum entanglement. Does anyone recall any previous discussion of quantum mechanics?


4/15/2014 at 2:57:34 AM GMT
Posts: 130
Good point, Sy. I don't recall Tyson mentioning quantum effects. Seems as if he wants to keep it simple and avoid technical jargon. As for photosynthesis being "heavily dependent on quantum entanglement," it is true that a number of reports in the past 5 years have indicated some quantum effects. The most recent paper a few months ago talks a lot about "non-classicality" but I couldn't find the word "entanglement" which is mainly used in headlines and other media reports whose explanations seem to me to be a bit different than what we usually consider entanglement. It does seem as if there are some key vibrational modes that can be understood only with some pretty sophisticated quantum physics.


4/15/2014 at 2:42:09 PM GMT
Posts: 51
They did graphically present the instantaneous orbital jumps of electrons. Perhaps they are building-up toward a better treatment of quantum mechanics and GR.



4/16/2014 at 7:30:15 PM GMT
Posts: 8
On the question of how long it takes photons to get out of the sun, I'll just quote what I put on Facebook.

I’m looking at Martin Harwit’s _Astrophysical Concepts_ (Wiley, 1973), the textbook I used the couple of times I taught the course. It’s 41 years old but as far as I know there’s been no major change since then in understandings of solar structure or radiative transfer.

From p.315, the mean free path L = 1/κρ, with κ the opacity and ρ the density, and according to Harwit, “For a star like the sun, κρ is of order unity, and the mean free path is of the order of a centimeter.” Now for photons doing a random walk, the distance travelled after N steps will be L√N, so the number of steps needed to go a straight line distance equal to R, the solar radius, will be given on average by L√N = R or N = (R/L)^2. The time taken to travel N steps of length L at speed will be t = NL/c = R^2/cL. R ~ 7.0 x 10^10 cm and t ~ 1.6 x 10^11 sec ~ 5000 years.

(Please excuse my explaining this in pedantic detail. I don’t get a chance to lecture on physics that much any more.)

Harwit notes that this doesn’t include time between absorption and reemission and says that the time is “at least” several thousand years. I don’t see any reason why in a star like the sun it should be greater by two orders of magnitude.

I saw a figure of 10,000 years way back when I was in high school, maybe in the science column Willy Ley used to write for Galaxy SF magazine. I remember being puzzled by it because he didn’t explain the process.