April 14, 2010
Reaching out to 100 billion galaxies
Something very strange is happening in science, says Dr. Chris Lintott, an astrophysics researcher at the University of Oxford.
“With the explosion in technology, for the first time in a long time we have too much data. Science will be driven by how creatively we can solve that problem.”
Speaking at a Perimeter Institute Lecture series in Waterloo, Ontario, Dr. Lintott told an audience of some 400 people that due to this explosion in technology, science is not just for those in ivory towers. Everyone can get involved.
Indeed, when scientists wanted to classify 1 million galaxies, they set up the website GalaxyZoo.org, which called upon web users to get involved. With the help of citizens all over the world they were able to classify these 1 million galaxies in three weeks. However, this is just the tip of the iceberg in terms of the universe.
That's 1 million galaxies out of 100 billion in the observable universe,” Dr. Lintott says. “The observable universe can be viewed at the University of Chicago.”
Since the GalaxyZoo website was launched on July 14, 2007, Dr. Lintott says 200 million galaxies have been classified by 270,000 people using the site.
“One hundred people look at a galaxy. They tell us how many spiral arms there are, whether it (the galaxy) has a bulge in the center and whether it's an elliptical or a spiral galaxy.”
He said elliptical galaxies have the oldest stars, while spiral galaxies have blue stars which are only about 100 million years old. These stars burn up their energy quickly.
Gases from stars smash together and the small masses that are formed smash into bigger masses, forming bigger and bigger stars, with the star formation rate being between 0.5 and 50 solar masses per year, Dr. Lintott said. After 200 million years all stars have little gas left to form galaxies.
“This is when black holes are formed. Three billion solar masses form a black hole in the center of a galaxy. Black holes are active players in the universe. If they're overfed material shoots out in jets creating a cosmic corkscrew effect. Elliptical star formations lose gas to black holes.”
He said black holes are a region of space cut off from our universe and light can't reach us from material in black holes. Their dark matter, consisting of 25 percent of the matter in the universe, hold the galaxies together. Black holes evaporate slowly and give off small bits of light, which is the equivalent to giving out their masses.
“We think something dramatic expels gas from a galaxy,” Dr. Lintott said.
The challenge for an astrophysicist is to explain how the universe came to be, he said.
“The universe was in a hot dense state 13.7 billion years ago (at the time of the big bang). We know the age of the universe better than the age of the earth. The evidence is pretty good. The Hubble (telescope) measured the distance to 20 galaxies. They're receding from us. The farther away they are the faster they're receding from us.”
The NASA webstie offers a more in depth explanation of this phenomenon:
“The precise measurements are the key to learning about the universe's rate of expansion, called Hubble's constant. Measuring Hubble's constant was one of the three major goals for NASA's Hubble Space Telescope when it was launched in 1990.
For the past 70 years astronomers have sought a precise measurement of Hubble's constant, ever since astronomer Edwin Hubble realized that galaxies were rushing away from each other at a rate proportional to their distance, i.e. the farther away, the faster the recession. For many years, right up until the launch of the Hubble telescope -- the range of measured values for the expansion rate was from 50 to 100 kilometers per second per megaparsec (a megaparsec, or mpc, is 3.26 million light years).
The team measured the Hubble Constant to be 70 km/sec/mpc, with an uncertainty of 10 percent. This means that a galaxy appears to be moving 160,000 miles per hour faster for every 3.3 million light-years away from Earth.”
Dr. Lintott used an artist's three dimensional drawing of cubes joined by rods to illustrate how the universe is expanding.
“The rods are expanding. All other cubes are rushing away from us. There is no real centre. We just think there is but the center could be any cube. Space itself is expanding.”
He added that when scientists look into the past, space is contracting and they see leftover radiation for the past. This early universe radiation causes interference with analogue televisions.
What started as a smooth universe with small fluctuations has evolved into a cosmic web due to gravity exaggerating differences in the density of particles and large density areas attracting more particles.
Dr. Lintott said scientists still don't understand 95 percent of the current model of the universe, so theory comes into play.
“In the 1950's they conducted the first big surveys of the skies, creating hundreds of images of the galaxies. In the 1980's they used still film to create images of thousands of galaxies.”
He added that now scientists are using a large synopsis telescope to create a video of the universe, not just images. Using this technique, they can scan the whole sky in three nights and track every astroid in the solar system.
By measuring the distance of the light emitted by supernovae – stars at the end of their lives that explode and can shine brighter than the whole universe – Dr. Lintott says scientists can determine how fast the universe is expanding.
“Supervovae always give off the same power so we know how far away they are, so we can measure the expansion of the universe.”
