Tag Archives: universe

Fun Science: Gravitational waves

Gravitational waves were first predicted in 1916 by Einstein’s general theory of relativity; today we are trying to directly observe them. A gravitational wave is a tiny oscillation in the fabric of space-time that travels at the speed of light; all other findings from general relativity predict its existence. Many objects will create minuscule gravitational waves, and even the largest objects create ones we just barely hope to see (such as binary stars and black holes). From the LIGO wikipedia page “gravitational waves that originate tens of millions of light years from Earth are expected to distort the 4 kilometer mirror spacing by about 10−18 m, less than one-thousandth the charge diameter of a proton.”

What would we gain from this? Astronomers believe that gravitational waves could eventually become another mode of imaging by which to analyze the universe, like gamma ray, x-ray, and infrared imaging.

Example of gravitational wave distortions (from wikipedia)

The LIGO (Laser interferometer gravitational-wave observatory) ran from 2002 to 2010; it was unsuccessful in its hunt for gravitational waves. It is being recalibrated to restart in 2014. The two observatories in Louisiana and Richland, Washington record the same events and compare the time at which they arrive. Below is a schematic of this set-up. LISA, the laser interferometer space array, has been discussed for years as an orbiting detector with greater length scales (and therefore greater accuracy) than LIGO; a proof-of-concept is due for launch in 2014.

Laser interferometer set-up (wikipedia)

If you want to learn more, Einstein Online, which is run by the Max Planck Institute, is a great resource (the Max Planck Institute is involved in great cutting edge research, perhaps comparable to NASA). The above link is for info on gravitational waves, but there is also great info on other concepts related to relativity if you are interested.

Fun Science: Astronomical

I first became interested in science when my brother told me there was a black hole under his bed (this was a ploy to prevent me from snooping there– this is how nerd children fight). Once I could read, I wanted to know if this could be possible; one should be skeptical of information provided by siblings. Frustratingly, none of the books I read discussed if an event horizon could be put under a bed. Pretty shoddy science. There was much discussion of micro-blackholes, with some description of their size. But what the heck was a nanometer? Bigger or smaller than a bed?

Even now, the scales of the universe boggle my mind. A human is so small. The diameter of the Earth (a small planet), is roughly 7 million times the height of a typical person. If you lined up every person in the state of Virginia head to toe, you would roughly approximate the Earth’s diameter. The diameter of the Sun is 100 times bigger (two orders of magnitude) than the Earth. If you lined up every person in the United States head to toe, you’d only get to half of the Sun’s diameter. The red giant Betelgeuse (the reddish star that is Orion’s left shoulder) is 700 times bigger than the sun.

The solar system is bigger yet–Neptune is 30 times as far from the Sun as Earth, at about 3200 times the radius of the Sun. It takes light 4 hours to reach Neptune. The Oort cloud, the farthest reach of our solar system and the hypothesized source of most comets, is a light year from the Sun.

From Wikipedia

Our solar system sits on one branch of the Milky Way, which is a galaxy 100,000 light years across (7×1011 times the diameter of the Sun–a meter is roughly 1012 times as big as a hydrogen atom). Our galaxy is 2.5 million light years from the nearest galaxy, Andromeda. Our galaxy is one of more than 50 galaxies in the Local Group. This piece of the universe is about 10 million light years in size. Wikipedia suggests there may be 100 billion galaxies in the universe. We have observed as far as 47 billion light years away, but the universe might be bigger (more intimidating statistics here).

And all of these things are slowly interacting. With all that, how could we not write science fiction?