According to theoretical cosmologist Anthony Aguirre, from the UCSC Department of Physics, the cosmic microwave background (CMB) radiation, which is radiation left over from the Big Bang, could hold the key of finding other universes.

CMB radiation is found throughout the universe. Many cosmologists study CMB radiation as a way to learn more about the Big Bang, the theoretical beginning of our universe.

After the Big Bang occurred, the young universe expanded quickly, in what is called inflation. Aguirre contends that inflation could still be creating “pocket universes”, sometimes also called “bubble  universes”.

Some cosmologists think that if these universes exist we would not be able to detect them. They contend that if one of these universes would collide with our universe, we would be instantly blown to pieces.

However, other cosmologists, like Aguirre, think that such universes exist, that they can be seen, and that collisions with them have a very low probability of destroying our universe. Whether we would be destroyed or not, however, hinges greatly on how different or alike each universe is to our universe.

Do the universes contain similar (or different) types of matter? Are the laws of physics similar (or different) in the universes? Of course, all of this is mere conjecture on the part of theoretical cosmologists.

Aguirre would like to extend this conjecture to facts. He thinks that distinct signs may be visible from CMB radiation, which already shows hot and cold spots—what are called large-scale anomalies. He thinks these hot and cold anomalies are related to these bubble universes.

English cosmologist Carlo Contaldi, from Imperial College (London), who is considered an expert on cosmic microwave background radiation, has indicated that Aguirre’s idea is possible. However, the only way to verify its accuracy is to perform additional research.

If Aguirre is correct, it could add great insight into the history of the universe, or, more precisely, the history of the universes.

Aguirre, along with colleagues Matthew Johnson and Assaf Shomer, calculated the probability of collisions of our universe with other universes. Their results, titled “Towards observable signatures of other bubble universes” appear at: http://www.arxiv.org/abs/0704.3473.

Information about Dr. Aguirre appears at: http://scipp.ucsc.edu/~aguirre/.

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