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Frontiers | Pages 178-179| (back to unlinked version)

Multiple Universes?

One of the most intriguing questions in cosmology is: What came before the Big Bang? One hypothesis, illustrated here, is that our universe may be just one of many that materialized out of the inherent instability of the cosmic vacuum. These vacuum fluctuations may be similar to an era of fluctuating foam known as Planck Time, 10­43 second after the Big Bang, before which our current models and theories do not apply. Some researchers speculate that the writhing foam would have produced tiny bubbles that appeared and disappeared--or suddenly expanded into entire universes.

How SMALL Does Matter Get?

For another cosmic mystery, it's not necessary to peer billions of light-years External Link: A review of how a light-year is defined and used. into space or back to the beginning of time. This mystery is right at your fingertips: What is the essential nature of matter? From the atoms of Democritus External Link: A biography of Democritus of Abdera. to the atomic nuclei of Ernest Rutherford External Link: A biography and description of the life and work of Ernest Rutherford, winner of the Nobel Prize in chemistry in 1908. to the quarks External Link: Some information about quarks, their charges and their masses. of Murray Gell-Mann External Link: A biography of Murray Gell-Mann, who received the 1969 Nobel Prize in Physics., our models of matter have shrunk to ever-smaller scales. It's natural to wonder whether this progression will continue, surprising us with even tinier nesting Russian dolls of matter. The answer is more than just a curiosity, because quantum mechanics External Link: A description of quantized energy states, the foundation of quantum mechanics. tells us that energy and matter fluctuate on these tiniest scales. In the earliest moments of the Big Bang, continual quantum fluctuations External Link: What IS a quantum fluctuation, anyway? dictated the future appearance of the universe--and they form the basis of all space and matter today.

Physicists peel back matter's layers by boosting electrons, External Link: Learn more about electrons. Internal Link:  protons , and other particles Internal Link:   to exceptionally high speeds and smashing them together. Our Earthly machines are pale versions of natural particle accelerators Internal Link:   in the cosmos. One of the closest is the Sun External Link: Learn more about our Sun, from an astronomical perspective., which pierces the inner solar system with writhing magnetic fields External Link: Learn more about magnetic fields and how they are created.. Charged particles Internal Link:   in the solar wind External Link: Learn about space weather, from NOAA's Space Environment Center. zoom outward along these field lines like surfers catching steep waves. Pulsars Internal Link:  , black holes Internal Link:   in the centers of galaxies, and other energetic objects also fling particles Internal Link:   into space at close to the speed of light. Accelerator energies on Earth are low by comparison, but they still allow physicists to simulate the conditions that existed fractions of a second after the Big Bang, albeit within volumes smaller than that of an atomic nucleus.

Decades of such research have constructed a scheme for the universe with a rather dry name: the standard model External Link: See and hear what particle physics is all about! Then follow the links to learn more.. This thorough model describes all known particles Internal Link:   in the universe and their interactions with precision. Its main ingredients are the four forces of nature--gravity Internal Link:  , electromagnetism Internal Link:  , and the strong External Link: Learn more about the strong nuclear force. and weak nuclear forces External Link: A quantitative discussion of the fundamental forces, including the strong and weak nuclear forces. --and two distinct sets of particles Internal Link:  . One set Internal Link:   consists of the basic units of matter as we know them today: quarks External Link: Some information about quarks, their charges and their masses., electrons External Link: Learn more about electrons. , and neutrinos External Link: Learn more about neutrinos, the ''little neutral ones'' of the universe.. Each of these types of matter falls into one of three "families External Link: A visual organization of the families of matter and their role in the standard model.," divided according to their masses. For the most part, the stuff of our everyday world features particles Internal Link:   in the least-massive family. The other two families External Link: A visual organization of the families of matter and their role in the standard model. arise mainly in particle accelerators Internal Link:  , both on Earth and in space. The second set of particles Internal Link:   in the standard model External Link: See and hear what particle physics is all about! Then follow the links to learn more. is fundamentally different.