AAS Wednesday: The multiverse, inflation, and a giant telescope

Posted by Liz Kruesi
on Thursday, June 05, 2014

Today was the last day of press events at the American Astronomical Society (AAS) meeting in Boston. The morning’s press conference actually overlapped with a science session about the multiverse — which I felt compelled to attend. I’m glad I did, because in the last decade, the idea of a multiverse has appeared to go from crazy to plausible … although I haven’t really understood why.

Cosmology greats Alan Guth and Max Tegmark gave wonderful presentations of why our universe is probably one pocket universe in a grand multiverse. /// illustration by Astronomy: Roen Kelly
During today’s session, two brilliant cosmologists provided a packed room with reasons why multiple universes likely exist. Alan Guth, one of the originators of the theory of inflation — that the universe experiences hyperexpansion during the first moments after the Big Bang — described how that theory would lead to infinite pocket universes, and the one we live in has laws of physics that make life possible. Max Tegmark then gave a presentation that described the idea of parallel universe, and why they make sense according to the current models of our own universe had evolved. Both Guth and Tegmark were excellent speakers; if given the chance to attend a talk by them, certainly take it!

I also attended a session about a possible future space telescope, which is in the early planning stages. Funding has yet to be allocated, but scientists are working on a design and the required technology for the possible Advanced Technology Large Aperture Space Telescope (ATLAST). To keep costs as manageable as possible, the ATLAST team is focusing on designs that can use existing launch vehicles (like the Delta IV rocket) and also deployment architecture and hardware adapted from the James Webb Space Telescope (JWST). The ATLAST scope would also be serviceable, so that the science instruments could be updated to help prolong the life of the mission, which is the Hubble Space Telescope (HST) has followed.

The next large-scale observatory will be JWST, an infrared telescope. After that, NASA is considering the Wide-Field Infrared Survey Telescope (WFIRST), another infrared observatory. The European Space Agency (ESA) has an X-ray observatory and a gravitational-wave instrument in its plan. But notice the absence of optical and ultraviolet (UV) instruments. That’s how ATLAST would fit it. It would be a UV/optical/near-infrared telescope, which would study star formation, galaxy formation, exoplanets, and other astrophysics science.

The Advanced Technology Large Aperture Space Telescope (ATLAST) is a 9.2-meter aperture space observatory in the early planning stages. It would use many of the technologies that have been developed for the James Webb Space Telescope. /// photo by STScI
Another way to make it less expensive is it won’t need to be cryogenically cooled. Instead, it could operate at 20° Celsius (68° Fahrenheit). That means ATLAST wouldn’t carry all the weight of a cooling system and it could undergo testing at room temperature.

The science team would like the telescope to hold the following instruments: UV imager, UV spectrograph, visible-light/near-infrared imager, visible-light/near-infrared spectrograph, starlight blocker (internal coronagraph or free-flying starshade), exoplanet imager, and an exoplanet spectrograph. A spectrograph breaks apart the collected light into individual colors, which can tell scientists what the light source is made of, how fast it’s moving, what direction it’s traveling in, and other details. A coronagraph or starshade would block the light from a star, allowing the telescope to find other objects near the star — like orbiting exoplanets or faint binary stars.

The ATLAST mirror would be made of up thirty-six 1.3-meter segments — the same size as JWST, but not made out of the same material. Instead of beryllium mirrors, which required some 10 years to make according to the scientists who presented today, the segments would be made of glass or silicon-carbide. The telescope would be isolated from the spacecraft, and a three-layer sunshield would deploy from below using four booms. (The sunshield would be a must simpler piece then the complex five-layer one of JWST.)

The most complex piece of the puzzle will be getting the optics extremely stable in changing temperatures. The team said the mirrors would need to be stable within 10 picometers (that’s 1 in 10 trillion) for the coronagraph to work properly. They have set an aggressive goal of determining most of the required technology within five years. By that time, JWST will have launched, and NASA will have a good start on the WFIRST instrument, which astronomers hope to launch in the early 2020s. Presumably, five years from now would be a good time to begin lobbying for funding for another NASA-led large-scale telescope like ATLAST.

We’ll have to wait and see what the future holds for ATLAST.

Read about Tuesday’s AAS activities.

Read about Monday’s AAS activities.

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