Before the Big Bang by Laura Mersini-Houghton

Author:Laura Mersini-Houghton
Language: eng
Format: epub
Publisher: HarperCollins
Published: 2022-05-14T00:00:00+00:00

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At first, the outcome of compactification struck the scientific community as a disaster.

Compactifying, a process to get rid of the extra seven dimensions and reduce the volume of space-time from eleven dimensions to four, indeed produces a universe like ours. But it also gave physicists far more than they had wished for.

It turns out there are a great many ways of curling up the extra dimensions and even more ways of combining layers of fluctuations of the quantum stuff in that extra volume. And for each possible option, another potential energy well,* known as landscape vacua, that can potentially ignite a Big Bang is produced. At present, using the mathematical process of compactification, string theorists have found approximately 10^600 (10 with 600 zeros behind it) possibilities. This vast collection of potential Big Bang energies, the collection of about 10^600 vacua obtained through the process I have just described, is known as the landscape of string theory.

The discovery of the landscape of string theory shook the world of theoretical physics to its core. The decades of efforts by string theorists to mathematically reduce the eleven-dimensional world of string theory to obtain solutions that describe a single four-dimensional universe had inadvertently unleashed the scenario of a virtual universe-making factory that could act as an incubator for many potential Big Bang energies from which billions of baby universes could possibly spring into existence.

If that seems like a lot to absorb, it is—even to seasoned physicists. However, there is a way we can envision a string-theory landscape as somewhat like the physical landscapes we are familiar with. It can have peaks and valleys, like a mountain range. But unlike the regular landscape on Earth, which exists in real space and time, the string-theory landscape exists in a space of energy—energies that represent the range of choices or possibilities that exist in this string world when trying to produce a four-dimensional universe. Just as on the familiar physical landscape a handful of marbles might roll down from a mountaintop and settle in a valley, in the string-theory landscape, a whole infant universe could settle in a place, a vacuum site. But the string-theory landscape contains a vast number of choices of vacuum energy sites from which our universe could have started. The new mystery in the context of the landscape discovery is which vacuum energy did our universe pick, and why did it pick that one?

The discovery of a string-theory landscape meant that, instead of one initial energy for one Big Bang type of inflation that resulted in one singular universe, there were an abundance of energies—many potential Big Bangs to start multiple, four-dimensional universes like ours. Instead of once and for all explaining our origin, this abundance of potential energies, trillions and trillions of possible starting energies so far (as illustrated earlier in this chapter), offered a mystifying multitude of possible origins. Simply put, a string-theory landscape provides a vast collection of initial energies—of potential Big Bang energies—capable of jump-starting multiple universes.

Unexpectedly,

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