UCLA physicist, astronomer explains dark matter, energy

By Mary Rose Fissinger and Vivien Mao


UCLA physicist and astronomer Dr. HanGuo Wang lectured on developing the machine engineered to detect dark matter. The optional meeting was during break on Nov. 2.

The machine will be lowered 1.5 km underground to detect the particle that is nicknamed SUSY. SUSY is suspected to be the substance known as dark matter.

Wang began by explaining what exactly dark matter is and how we know that it exists.

One example of evidence for dark matter, according to Wang, is the leftover radiation from the Big Bang. This is still observed today when one examines the sky.

The universe is at a general temperature of -270 degrees Celsius. When scientists Arno Penzias and Robert Wilson accidentally discovered cosmic background radiation, they were able to calculate the temperature of the universe. This leftover radiation is a dark matter component.

Another example Wang gave was the speed of a galaxy spinning outwards. The expected outcome is that the galaxy would spin slower as it stretched away from the sun, as according to Newtonian law, but instead, the observed outcome was that the galaxy actually spun faster as is went away from the sun. This could soleley be caused by a gigantic mass, which could only be of dark matter.

He also spoke about the make-up of the universe, with everything other than dark matter and dark energy making up only five percent of the universe. Dark matter only takes up 25 percent, but dark energy, which is still unexplainable, makes up seventy percent.

“I learned all about half of the universe that I never really knew existed,” Chris Holthouse ’11 said.

Wang followed this overview of dark matter by speaking specifically about what his research concerns: WIMPS, Weakly Interacting Massive Particles. He searches for WIMPS by using liquid xenon lead to try to capture dark matter.

The Large Hadron Collider in Geneva created a controversy last year when rumors started that it could potentially create a black hole on Earth. It is a device which would capture dark matter, but was shut down due to a malfunction.

Wang, who has worked on many research projects, was involved in the construction of the ZEPLIN II, another LHC, in England, and is now working on the HARBIN in China.

Wang explained that he was trying to capture dark matter by luring it into the LHC with electrons, which seems to be what it is attracted to.

Wang and his group of scientists line each LHC with atoms and start up the machine, also lined with special lights to see the radiation.

All of this is impossible with the background elements in the earth, especially radiation coming from space.

Wang said all of the experiments are held very deep underground to reduce background radiation. The deepest LHC is in China.

“I didn’t even mean to go [to the speech]; my friend dragged me along,” Hank Adelmann ’11 said, “but it ended up being really cool and I learned a lot.”

At the end of his presentation, Wang laughed and jokingly predicted, “within the next decades, the nature of dark matter that holds our universe together will be discovered by a Harvard Westlake graduate.”

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