kottke.org posts about universe

Personal light conesDec 02 2008

When I was born 35.2 years ago, a light cone started expanding away from Earth out into the rest of the universe (Minkowski space-temporally speaking, of course). Thanks to updates from Matt Webb's fancy RSS tool, I know that my personal light cone is about to envelop the Zeta Herculis binary star system, located 35.2 light years from Earth in the constellation Hercules.

With a mass some 50 percent greater than the Sun, however, and beginning its evolution toward gianthood (its core hydrogen fusion likely shut down), Zeta Her A is 6 times more luminous than the Sun with a radius 2.5 times as large. Nevertheless, the star gives a good idea of what the Sun would look like from a great distance, in Zeta Her's case 35 light years. The companion (Zeta Her B), a cooler class G (G7) hydrogen-fusing dwarf with a luminosity only 65 percent that of the Sun and a mass about 85 percent solar, orbits with a period of 34.5 years at a mean distance of 15 Astronomical Units (over 50 percent farther than Saturn is from the Sun). A rather high eccentricity takes the two as far apart as 21 AU and as close as 8 AU.

Hercules is of course named for the Greek hero, Heracles. Next up is Delta Trianguli, another binary star system, in about two months.

Fractal universeJun 26 2008

Is the universe fractal-like, even on large scales? A group of Italian and Russian scientists argue that it displays a fractal pattern on a scale of 100 million light years. Other scientists aren't so sure.

Many cosmologists find fault with their analysis, largely because a fractal matter distribution out to such huge scales undermines the standard model of cosmology. According to the accepted story of cosmic evolution, there simply hasn't been enough time since the big bang nearly 14 billion years ago for gravity to build up such large structures.

Are there many small galaxies, like theJun 06 2007

Are there many small galaxies, like the one just discovered just outside our own, orbiting the larger visible galaxies?

Three trillion years from now, the universeMay 31 2007

Three trillion years from now, the universe will be observably static, the Milky Way alone, and scientists of the day likely won't be able to "infer that the beginning involved a Big Bang".

Happy birthday, universeOct 23 2006

According to the Ussher-Lightfoot Calendar, today is the 6,009th birthday of the universe. Based on James Ussher's interpretation of the Bible, God created "the heaven and the earth" on October 23, 4004 BC. Happy birthday, everything!

Note: I'm doing Mr. Ussher's precise chronology a disservice by fudging the Julian calendar date that he derived with the Gregorian calendar we now use. For that, I apologize.

Stephen Hawking and Thomas Hertog are publishingJun 21 2006

Stephen Hawking and Thomas Hertog are publishing a paper that argues that the universe "began in just about every way imaginable" simultaneously and then most of the possibilites withered away with the rest blending together to make the current universe.

Maybe the universe is a trillion yearsMay 05 2006

Maybe the universe is a trillion years old and has experienced several big bangs and big collapses over the years. "People have inferred that time began then, but there really wasn't any reason for that inference. What we are proposing is very radical. It's saying there was time before the big bang."

Jim Holt asks Freeman Dyson, Lawrence Krauss,Oct 31 2005

Jim Holt asks Freeman Dyson, Lawrence Krauss, Ed Witten and other in trying to figure out how the universe will end. Further reading: Time Without End by Freeman Dyson, Frank Tipler's Omega Point theory, and The Physics of Extra-Terrestrial Civilizations by Michio Kaku.

Tags related to universe:
physics science cosmology bigbang time astronomy space

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