Astronomy/M-theory

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Question
Hi,
 I have a question about M-theory and the other dimensions it implies must be there.I know that at this point they are theoretical but for sake of argument and for this question lets take M-theory and assume its a fact. With that said, I understand that it states that there are the 3 dimensions we live in, plus time and then 7 other dimensions we are unable to perceive for a total of 11.Understood completely.
My question is that the way that these 7 dimensions are usually described is as tiny little strings that are everywhere, on your body, in the air, everywhere. However that's basically as far as they go. Maybe that is because it is hard to describe something that is really just hypothetical, or maybe for a scientist, that is enough of an explanation. However for me it isn't. I guess because I am a layman and because I am so accustomed to thinking of things as we know them, in 3-D I have an extremely hard time understanding and picturing what those dimensions are actually like. Ok, lets say that the other 7-D are tiny string like dimensions that surround us. If we were somehow able to enter those, what would/could they be like(Hypothetical of course)?If its impossible to really know, I get that. If that's the case really I am just asking for your educated opinion.Something to help make it easier to imagine.
I've wondered this for a long time.
Thank You

Answer
Hi Jason,

Yes, I won't go into the debate or merits (or lack thereof) of String/M-theory.  

Firstly, there are 4 fundamental dimensions.  Our normal 3 spatial dimensions, but also the 4th which is time.  Time is (in my opinion) the most important and coolest dimension, but I'll leave that for another time.

Now, let's focus on the extra dimensions you get from String/M-theory (6,7, 10, or even 26)!  Firstly, the origin of String/M-Theory is to find a way to connect all of the fundamental forces (electromagnetism, weak, strong, and gravity) and also all of matter into one thing at one time.  The easiest way to do this is by having more than the four dimensions we know and love.

These extra dimensions would operate on a much smaller or larger scale.  The more popular idea is that our Universe (and dimensions) operates in a larger framework (called a Brane) wherein these extra dimensions lie. This would explain why in normal physics we don't interact with these dimensions, but also explains how our Universe came to be.  Imagine a bunch of cars with people in them on a ferry.  The people cane move around in the car, but the car itselfs moves on the ferry. This would be like what our Universe is doing in this larger framework, the Brane.

The other scale, the smaller scale, says that these dimensions exist on a completely smaller scale inside our Universe, but this is harder to reconcile.

I hope this all makes sense.

Peace,
Brad

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Brad Tucker

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I'm happy to answer any general questions about Astronomy, Astrophysics, and Cosmology. I'm also happy to take general, specific, and detailed questions related to supernovae, Baryonic Acoustic Oscillations, the Cosmic Microwave Background, dark matter, dark energy, and the Big Bang Theory. I'm also happy to chat about Astronomy/Astrophysics education and careers, and philosophy and science.

Experience

I am a professional research astronomer/astrophysicist/cosmologist. My research focuses on studying supernovae and using them to measure the properties of the Universe, such as how fast it is growing and what it is made of. I also frequently give talks to school groups and the public, and am a regular guest on various radio stations.

Organizations
Current Research Fellow at Mt. Stromlo Observatory, the Australian National University, and in the Department of Astronomy, University of California, Berkeley.

Publications
Lots of journals, including the Astrophysical Journal, the Astronomical Journal, and Nature. I am currently in the middle of writing my first popular book.

Education/Credentials
B.A. Philosophy, University of Notre Dame, Notre Dame, IN USA B.A. Theology, University of Notre Dame, Notre Dame, IN USA B.Sc. Physics, University of Notre Dame, Notre Dame, IN USA Ph.D. Astrophysics, Mt. Stromlo Observatory, the Australian National University, Canberra, ACT, Australia

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