Astronomy Question: What is Outside of the Universe?

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Veronesa asks,

Dear Astronomer,
What is on the outside of the universe? Is there an outside of the universe?

Excellent question Veronesa!

Many people speculate at what (if anything) lies outside our Universe. In the past I’ve been asked where the Big Bang happened, and if there’s a center to our Universe. Where did the Big Bang happen? Everywhere. When did the Big Bang happen? At the beginning of time, about 14 billion years ago.

Given the tidbits of information above, once can easily begin to speculate about what, if anything, lies outside our existence in our Universe. Keep reading to learn more about the science (and philosophy) of this rather existential question.

I’ll be the first person to admit that cosmology gives me headaches – I much prefer to stick with observational astronomy. While there is a good amount of actual science involved in the field of cosmology, there’s also a significant amount of theoretical physics.

Many cosmologists theorize that our universe might be one of many in a “multiverse”. Additionally, theoretical physicists state that it may be possible that new universes are constantly being created, and that an infinite amount of universes exist. The “many worlds” interpretation ties quantum mechanics and probability to the multiverse theory, stating that all potential outcomes to a given situation do, in fact, occur. Interestingly enough, many science-fiction movies and television shows have explored the concept of alternate realities/universes.

Given the “many worlds” interpretation, it’s plausible that many “alternate” universe would have different laws of physics, with some universes ceasing to exist in fractions of a second, and others being nearly identical to our own.

One important thing to remember is that the definition of the universe is “everything” – time, space, matter, energy, etc. Most physicists agree that you can’t have something outside of “everything”. When cosmology delves into such large-scale topics as the universe itself, the debates can be just as much science as conjecture and philosophy. Also, what we perceive as the universe is merely the “observable” universe.

If you’d like to do some scientific reading that explores cosmology, try these papers:

Observational Implications of Cosmological Event Horizons
Topology and the Cosmic Microwave Background

You can also learn more from theoretical physicist (and cosmologist) Dr. Lawrence Krauss.
Here’s a video from his “A Universe From Nothing” series of talks:

Ray Sanders is a Sci-Fi geek, astronomer and blogger. Currently researching variable stars at Arizona State University, he writes for Universe Today, The Planetary Society blog, and his own blog, Dear Astronomer