Category Archives: Physics

Logarithmic history or geography class

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What if there was a class that attempted to cover all of space or all of time?

I was curious about this, so I chose the shortest scale of each, divided up the power of tens, then spread them out over the course of 10 to 12 weeks.

For example, for time, I chose 1 year as the smallest range to look at – the first week’s topic would cover the past 10 years. Then, since the universe is about 12 billion years old, or 1.2 \times 10^{10} years, each week would look back another factor of 10 years. The 2nd week would cover the period from 100 years ago to 10 years ago, and so on.

In practice, this would be the topic coverage for a 1-semester history lesson (I’m obviously glossing over some important topics):

“History” Class

Week Years ago Topic
1 10 a Last 10 years
2 100 a World Wars, information age
3 1000 a modern religion, science, industry
4 10,000 a development of human agriculture
5 100,000 a development of clothing, fishing, domestic animals, art
6 1 Ma Homo erectus, neanderthals, Homo sapiens, controlled fire
7 10 Ma beginning of horses, insect diversification, chimpanzee and human ancestors divide, mammoths, ice age
8 100 Ma whales return to sea, bees, T. rex, South America leaves Antarctica, Atlantic Ocean forms
9 1 Ga possible Snowball Earth, first protozoa, worms, fungi, arthropods, continents shift, land-dwelling life starts, Pangea, dinosaurs
10 10 Ga Big Bang, galaxies form, solar system and Earth form.

“Geography” class

On the other side of things, a space-centered class could break down like this:

Week Distance away Topic
1 100 m South Loop, Chicago
2 10 km Chicago
3 1000 km Midwest USA
4 100,000 km Earth
5 1 au The sun and inner planets
6 10 au All planets in the solar system
7 1000 au Kuiper belt on edge of our solar system
8 1 ly Oort Cloud on edge of our solar system, nearest star Proxima Centauri
9 100 ly local stellar neighborhood
10 10,000 ly Milky Way Galaxy
11 1 Mly Local Group (of galaxies)
12 100 Mly Observable universe

Kinda puts things in perspective for me. I forget, sometimes, how big our solar system is, and how recent humans came into being.

Additionally, it strikes me how interdisciplinary either of these courses would need to be. Crossing scales of time and space requires different lenses and tools.

Midwest Theory Get-Together 2013

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I was excited to attend the Midwest Theory Get-Together at Argonne National Lab again this year. There were many interesting talks, and I was glad to get an update from the many diverse fields of nuclear theory.

I was especially excited about the last talk of the second day. Mridula Damodaran from Purdue gave a talk about parallelizing the BUU transport model. I wish her success, as I’ve been using a BUU simulation for awhile and the longer simulation runs take 1-2 days — a bit longer than is convenient.

During the Get-Together, I recorded the titles of all the talks that were given, in case I wanted to reference them later, and in case others did too. This record is attached to this post.

Student epiphany in the physics lab

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In Carl Sagan’s book Pale Blue Dot: A Vision of the Human Future in Space (1994), page 159, the renowned astronomer and science popularizer wrote:

It is sometimes said that scientists are unromantic, that their passion to figure out robs the world of beauty and mystery. But is it not stirring to understand how the world actually works—that white light is made of colors, that color is the way we perceive the wavelengths of light, that transparent air reflects light, that in so doing it discriminates among the waves, and that the sky is blue for the same reason that the sunset is red? It does no harm to the romance of the sunset to know a little bit about it.

(as quoted in Today in Science History)

I had that kind of experience in the introductory laboratory I was teaching yesterday. We were using a digital spectrometer to investigate the wavelengths of light that were emitted from various objects like gas discharge tubes and the ceiling lights. The students learned that there was very little red in the ceiling lights, so that’s why red things in the room always look faded, and especially that the red light from the computer monitors looked more vibrant than the light from the paper. One surprised student said to me, “So we can’t even trust our eyes in this experiment?!”

This is the epiphany that I live for in the classroom – that the world we perceive is not always the world as it is, and we can use tools and science to help remove some of our biases.

This, to me, is beautiful.

Kepler Confirms First Planet in Habitable Zone of Sun-like Star

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From NASA Science:

The newly confirmed planet, Kepler-22b, is about 2.4 times the radius of Earth. Scientists don’t yet know if Kepler-22b has a predominantly rocky, gaseous or liquid composition, but its discovery is a step closer to finding Earth-like planets.

This goes to show how we have so much more to learn about our universe. Astronomy is just one of the very exciting fields today.