Posted August 13, 2001
Australian astronomer Dr. Brian Schmidt has been involved in research which is measuring the rate at which the Universe is expanding, and believes that a mysterious 'dark energy' may be pushing it apart. He talks to Jennifer Laing about his award-winning work and interest in international astronomical projects, such as the Next Generation Space Telescope and Square Kilometre Array.
Astronomer Edwin Hubble's work in the 1920's showed that clusters of galaxies are getting farther and farther apart as time goes on, moving away with a speed which is proportionate to its distance from our galaxy. Some of the most recent research, according to Hubble's modern-day counterpart, Australian astronomer Dr. Brian Schmidt, suggests that this process of expansion of our Universe is in fact accelerating.
Dr. Schmidt, 34, based at the Australian National University (ANU) Research School of Astronomy and Astrophysics since 1995, leads the High-Z SN Search team, a group of 20 astronomers on 5 continents using distant exploding stars (supernovae) to measure the expansion of the Universe.
The High-Z SN Search team postulates that gravity, which once slowed down the Universe's expansion, has in fact been overcome by a repulsive form of gravity caused by a mysterious "dark energy." Their work involves the most distant supernova or exploding star ever observed. This supernova is a special class of explosion that allows astronomers to measure the cosmological expansion very accurately, says Schmidt.
"By measuring how bright the explosion appears on Earth, we are able to deduce how many light years the supernova is in distance. We can also measure how fast the object is moving away from us, by seeing how red its light has been stretched by the expanding Universe [referred to in astronomy as the 'redshift']. Comparing the object's distance to how fast it is moving away from us, we measure the speed at which the Universe is expanding at the time of the explosion - some 10 billion years ago."
According to Schmidt, the supernova "happened 10 billion years ago when the Universe was only about one-quarter its present age, at a time before gravity lost its grip and the Universe began accelerating. Five billion years later, the Cosmos had spread apart, lessening the effect of gravity, and opening the door for something else, whose nature is still not clear, to push the Universe apart." This "something else", says Schmidt, "has been labelled 'dark energy.'
Heading the international High-Z SN Search team at such a young age is a feather in Schmidt's cap. He explains his role by saying, "It was at my initiation that things got going. I was working in supernovae and saw an opportunity to use them to measure distance in astronomy very accurately. It was the perfect time to 'get in there'. I got a group of friends together and told them I'd write the software if they could help write the proposals. I suppose it was unusual for a 26 year old to become head of this, but then again, I was doing most of the work." He will continue as leader of the team for the short-term, but would prefer to take a back-seat at some stage. "The group is big enough and diverse enough that it will probably reform in the next few years. I'm more interested in the science than in running the group."
Growing up in Alaska and Montana in the United States, Dr. Brian Schmidt has Bachelor degrees in Physics and Astronomy from the University of Arizona, and a Masters and Ph.D. in Astronomy from Harvard University. He says he was "always interested in doing science," and "when I was a child, I used to look at the stars and had a telescope." However, he says he didn't give astronomy "much thought, as something I would spend my life doing." He started work at the National Weather Service in the United States, but "didn't really see the science side of meteorology. I thought [studying] astronomy might be fun." In this respect, Schmidt has something else in common with Edwin Hubble, after whom the Hubble Space Telescope was named, who studied law before turning to astronomy!
Schmidt came to Australia after meeting his Australian-born wife at Harvard. "Australia seemed like a good place to live. I had an uncle here and spent a lot of time here as a child." His C.V. over the past few years is an impressive one. Schmidt has received a variety of prestigious science awards, including the Australian Academy of Science Pawsey Medal in 2001, the Australian Government's Malcolm McIntosh Prize, and the Bok Prize for the outstanding Astronomical Thesis, Harvard University, in 2000. In 1998, his research in discovering an accelerating Universe was named the 1998 Science Magazine's 'Breakthrough of the Year.'
One of the youngest members of the ANU staff, Schmidt is also involved in their Community Continuing Education courses on astronomy, and doesn't see anything unusual in an award-winning scientist being involved in this type of activity.
"I believe strongly in community outreach, so I guess you need to put your effort where your mouth is! Eight different people deliver the lectures and I oversee it. It's fun to deal with the public, and important to do it, and do it well."
One of the speakers at the 2000 Space Futures conference in Canberra, Australia, Schmidt was impressed "that a group of young, very able people interested in engineering, space, science and technology could put that conference together on their own. He feels that in the 21st century, "science and technology will be done by groups of people working together and learning together, sharing information."
With respect to his own future plans, Schmidt has a deep interest in several proposed international astronomical projects, such as the Next Generation Space Telescope and the Square Kilometre Array, and sees their relevance and substantial benefits to Australian astronomy.
The Next Generation Space Telescope (NGST), proposed to be built and launched by 2009, will use imaging and spectroscopy in the infrared to study the earliest stars and galaxies. The NGST will be 10 times bigger in area, and 100 times more sensitive than the Hubble Space Telescope (HST), which it will replace. According to Schmidt, "The NGST will open up a new window on the cosmos. By looking at the first supernovae as they explode, it will let us look at the Universe when it was first formed. A lot of my research will be dependent on it."
As with the current time allocation process on the HST, users of the NGST will be selected from proposals provided by qualified observers at US institutions. If other countries become involved in the construction phase, their qualified observers will also be able to apply for time on the NGST. Currently, construction costs for the NGST are not to exceed $500 million, less than one quarter of the costs of the Hubble Space Telescope, and the total cost for the mission, including launch and ten years of operation, is estimated at $U.S. 1 billion. Australia may be able to help build an instrument for it, which Schmidt says would have commercial spinoffs for the nation. "It could also be the entrance into satellite building in a major way for an Australian company."
He notes that Australia will probably need to be a partner in the NGST, if we want our scientists to have future access to the facility. "It will bring Australia into the international group, as astronomers. There is a good chance that we will not be able to apply for time on the NGST [without being a partner] and that there will be pre-programmed science. The development work and science is being determined now. The question is, are we going to be part of it?"
Dr. Schmidt also enthusiastically supports Australian involvement in the Square Kilometre Array (SKA), which will be an array of radio antennas with a collecting area of one square kilometre (one million square metres), about 100 times as great as the biggest present-day instruments.
"Australia is the best physical location on Earth to build this thing. My hope is that we site it here and negotiate access to it in exchange for access to the NGST. West Australia is the front runner for the core, but the SKA is so big, every state and territory will probably have several pieces of the antenna on site. It is proposed to be shaped like a giant nautilus, extending from coast to coast. It is possible the core could be located in a variety of states."
There is a trend towards international cooperation in large space projects, and Schmidt sees the benefits in this sort of approach. "It's too expensive for single nations to do this. Even the United States has trouble coming up with the cash. Also, we have a certain expertise here which the U.S. can use, and vice versa."
The consequences for Australia if it doesn't become involved in these projects, says Schmidt, are serious. "It would undermine our whole astronomical effort. We have a rich history in astronomy and our influence these days is as high as it has ever been. Our astronomers are extremely productive, and the impact and number of our published work is among the highest in the world." Involvement in both projects makes sense, "as we can't put all our eggs in one basket."
"We need access to both these instruments, as they involve different scientific goals. Failure to do so could doom us to irrelevancy on the world [astronomical] stage."
Jennifer Laing is a freelance space writer from Melbourne, Australia.