There is no such thing as karma, at least not for stars and galaxies in a universe cycling through a series of big bangs and big crunches. Apparently whatever happens to stars and galaxies in the present universe doesn鈥檛 affect them in their next incarnation.
The cyclic universe model was proposed in 2002 by Paul Steinhardt of Princeton University and Neil Turok of the University of Cambridge. In their model, the universe bounces through a series of big bangs and crunches, with each cycle lasting about a trillion years. The model solves some of the problems with the standard big bang theory, and the researchers have also used it to explain the mystery of why the cosmological constant, which governs the rate of acceleration of the universe鈥檚 expansion, is so small (快猫短视频, 15 May 2006, p 10).
However, the model has been dogged by a problem. It assumes that at every big bang the amount of matter and radiation in the universe is reset to zero, so there was always a worry that unwanted stuff from one cycle would bleed into the next. 鈥淲e needed to prove that structure created in one universe wouldn鈥檛 mess up future universes,鈥� says Steve Gratton, also at the University of Cambridge. 鈥淲ould bits of the Earth spill through from the previous universe into the next one?鈥�
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鈥淲e needed to prove that structure created in one universe wouldn鈥檛 mess up future universes鈥�
Now Steinhardt, Turok, Gratton and Joel Erickson of the Columbia Astrophysical Laboratory in New York have resolved the problem by looking at the quantum fluctuations in the early universe that cosmologists believe gave rise to structures such as galaxies. The team showed that during a big crunch event, these quantum fluctuations are amplified, while any matter is squelched. 鈥淭he fluctuations end up swamping the remnants of the matter that was there,鈥� says Gratton.
The result is that while any structure is destroyed, the quantum fluctuations survive through to the new universe, ready to give rise to a new generation of stars and galaxies (). 鈥淵ou begin each cycle from essentially exactly the same starting place,鈥� says Gratton.
鈥淚t is important to create this clean slate for each successive cycle,鈥� says cosmologist Martin Bucher at Paris-Sud University in France. 鈥淭his was the shortcoming of earlier cyclic models, but they have overcome that difficulty.鈥�
There is still one problem, however. If the fluctuations in each new universe are ones left over from the previous cycle, how did the fluctuations in the universe at the start of the chain originate? 鈥淚t鈥檚 an important question and one that we don鈥檛 have an answer to,鈥� says Gratton. 鈥淏ut then, that鈥檚 the big question for every cosmological model: where does it all come from in the beginning?鈥�
