12. Coming of Age in the Anthropocene

Assignments

• Watch Episode 12, and submit your comments and questions by way of the forms, as usual.

• Bring an elastic (aka rubber band) to class. A thick one is best.


Before class, try this:

1) "Take the temperature" of the elastic by touching it to your lips. 
2) Stretch the elastic hard (until it will hardly stretch any more), and immediately, while holding it stretched hard, touch it to your lips. Did its temperature change? Describe the change.
3) Continue to hold it stretched hard for at least 30 seconds.
4) Touch the stretched elastic to your lips, then quickly let it relax, and touch it to your lips again. Did its temperature change? Describe the change.
5) Think about how you could use the elastic as a refrigerant, to move heat out of one room into another.

• UNEXPECTED OPPORTUNITY: Your classmate Walter Allan carried out the "quantum eraser" two-slit experiment described in the resources on the Episode 9 page. Here is that information:

A Do-It-Yourself Quantum Eraser!! 
The May 2007 edition of Scientific American provided instructions on using simple apparatus for seeing quantum interference and demonstrating how observation changes the outcome of quantum experiments. Seeing interference is surprisingly easy. The other experiments are more challenging, but it you are good with your hands, you might pull them off. In addition to common household items, you will need a couple of odd items: a laser pointer, and polarizing film.

You can see Walter's results HERE. Walter consented to describe his work at the beginning of the next class, so have a look at this article. Be prepared for some good help at better understanding this quantum mystery. I can't wait.

A key to understanding how the photons are "observed" or "not observed" is to polarize them as they pass through the two "slits" (actually in this experiment, the two sides of a wire). Watch this video to learn about how polarizing films or lenses work.

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To think about
for Episode 12, "Coming of Age in the Anthropocene"

• In your opinion, when did the Anthropocene era begin?

• What is carbon-14? How does it get into our bodies? Under what circumstances can it tell us the age of a biological sample?

• What is iridium? Why does a thin geological layer enriched in iridium signal a cataclysmic event long ago on Earth? Why is this layer found practically everywhere on Earth?

• Why are refrigerants like CFCs harmful beyond what their quantities would suggest?

• Do you know how your refrigerator works?

Questions for Discussion

Student questions will appear here

Steve brought up an interesting question about the photon moving in space vs. moving in time. Difficult to think of. But, how about things moving faster than light - like distant galaxies. Here is Veratasium on this and the Hubble Sphere: https://youtu.be/XBr4GkRnY04

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A thread:

A: The laws of probability give pessimism for human survival.  Suppose the probability on any given day is one in a million that a catastrophic event will wipe out civilization.  Laws of probability say our surviving 2,000 years are just 1/2.

B replies: If the probability were 1 in a million of not surviving the year then our chances of surviving would be .999999 and it would take 693,146.834 years for the probability of surviving to be 0.5.

A replies: Just looked at today’s new student questions/comments.  Just to note that the last one - the probability calculation - is correct, too.  It just assumes a chance of catastrophe as 1 in a million per YEAR rather than my assumption of per DAY.  So he/she gets about 700,000 YEARS instead of DAYS as answer.

A continues: But also to note that the same kind of calculation shows that 2.7 x (10 to the -9) chance of catastrophe per day =  1 x (10 to the -6) chance of catastrophe per year.   Which odds per day of a catastrophe is a more likely assumption?  Order of one in a million or one in a billion?  Has anyone (or organization) estimated this?

And A wraps it up: Last time I will bother you about this! 
I found this (below)  in Wikipedia.  Under this assumption, the probability we will be around in 2,000 years is only 1%. 
“ Given the limitations of ordinary calculation and modeling, expert elicitation is frequently used instead to obtain probability estimates.[15] In 2008, an informal survey of experts on different global catastrophic risks at the Global Catastrophic Risk Conference at the University of Oxford suggested a 19% chance of human extinction by the year 2100. The conference report cautions that the results should be taken 'with a grain of salt'; the results were not meant to capture all large risks and did not include things like climate change, and the results likely reflect many cognitive biases of the conference participants."

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This is a spoiler for the rubber band experiment... so watch after class: Richard Feynman on rubber bands: https://youtu.be/nYg6jzotiAc?t=730

[[  from GR: Go ahead and look at it. In this demo, there are many subtleties I only saw on repeatedly reading and thinking rubber band contraction and other entropy-driven processes. In addition, Feynman's is a physicists way of looking at this, and mine is a chemist's way, which makes the molecular events more understandable. The differences are interesting. ]]

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Astrobiologists are interested in the origins of life and the future life in the universe by studying extraterrestrial materials collected in samples from space missions. Has any molecular growth developed from those materials suggestive of a possible plant or animal, etc? Or, is everything still based on probabilities, theories and correlations?

[[ from GR: See Other Resources, below, about experiments to find pathways by which the molecules of life might have formed from all kinds of substance that were present on primitive Earth, or that have been found in space and on asteroids and meteorites. ]]

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Hard to think of a question when the end of the episode seemed so dire and almost hopeless.  Are there groups of scientists, etc., working on this problem?  I don't have an answer, but are new ones appearing often?  Ones that have a possibility of working?  And it sounds like whatever great idea is finally chosen it will need a certain percentage of people/countries to agree to the plan.  Are other countries (like China) also thinking about this?  Do we even know if they are?

[[ from GR: See a range of climate change efforts: https://g.co/kgs/HFMfSG. 

Read about all aspects of climate change and responses, both taken and proposed, at Wikipedia. ]]

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••••••

Other Resources

• What are CFC's, and how do they destroy ozone?


Vocabulary Note: When the narrator describes free chlorine atoms as acting as "enzymes", it is more accurate to say they act as catalysts, a more general term. Catalysts make specific chemical reactions proceed faster (chemists say they promote those reactions), but are not themselves consumed in the process (for example, a chlorine atom can cause an ozone molecule to break down faster, but can find another ozone molecule and do it again, and again).  Enzymes are biological catalysts made of protein or RNA, so they are catalysts of a specific class. Catalysts can be reactive atoms like chlorine, surfaces of metals, complex molecules like intestinal proteins involved in digesting foods -- any substance that makes a specific chemical reaction proceed faster, but is not consumed in doing so. 

• Tyson mentions the chemical composition of the atmosphere on early Earth. It would not have supported life as we know it. Yet it contained the seeds of biomolecules, as shown first by the Miller-Urey experiment, and subsequently by many other experiments that produce the molecules of life from primitive-earth chemicals and conditions. Read about the Miller-Urey experiment at Wikipedia.

From Stated Clearly, here is a brief overview of the experiment and its context:


Finally, click HERE to read a recent (quite technical) article in Science about a powerful process of prediction and testing, aimed at finding plausible primitive-earth pathways to a myriad biological molecules. If you are not able to access the full article, let me know and I'll help.



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