Tuesday, April 24, 2012

What is "nothing"?

The definition of a fundamental word is often the most important part of a philosophical debate.  This is especially the case in the debate over how “something” arose from “nothing.”  The word nothing is the tricky word here because it is hard to imagine what "nothingness" would actually be or what we actually mean when we say the word nothing.  This difficulty can be seen in a recent criticism of a book by Lawrence Krauss.

Lawrence Krauss recently wrote a book explaining how modern cosmology and quantum mechanics can answer the question of how our universe could have arisen from empty space.  However, this book is not without criticism.  David Albert submitted one such criticism as a book review in the New York Times.  The problem is Albert failed to fully think through his argument.

 Let’s start with a basic introduction to Kraus’s argument—a very basic introduction.  Kraus points out that quantum mechanics shows us that particles can spontaneously appear from what we would consider empty space and that this may be a way to explain how something arises from nothing.  Albert criticizes this by using his own definition of nothing.  He argues that because particles can actually arise out of this empty space that it is not actually “nothing” because something must exist from which these particles can arise.  Albert correctly points out that in this empty space the laws of physics that allow particles to spontaneously appear must still exist.  Thus, Albert is stating that because the empty space had potential to become something that in fact it was not really nothing at any point.  Here, Albert has defined nothing to require that it be some sort of emptiness that has no natural potential to become something.

You may have already noticed the fatal flaw in this argument: as Albert has defined it, “nothingness” cannot exist.  If there was such a nothingness then something could not have come from it because by definition the potential to become something makes it not nothing.

If my repeated use of the words something and nothing is a bit confusing let me try to explain this in another way.  Albert’s argument will apply to any explanation of how something came from nothing.  Say for example I claim that god created the universe from “nothing.”  Albert would point out that the universe didn’t in fact come from nothing; it came from the already existing god.  Additionally, whatever God created the universe from wasn’t really nothing either because it had the potential to be turned into something by god.  Thus whatever god turned into something could not have been nothing.  Any time someone tries to explain how something came from nothing Albert can simply point out that there was never really nothing in the first place because the possibility that it could turn into something always existed.

Albert’s problem is that he has defined the word “nothing” in a way that makes it impossible for there ever to have been a state of “nothingness”.  The fact that the universe currently exists means that there was always the potential for something to arise and thus by Albert’s definition there has always been something.

What this illustrates is the difficulty of using the word “nothing.”  The idea of “nothingness” may not even make sense when applied to the existence of our universe.  Generally we use the word nothing in everyday contexts rather than to explain our world.  For example, when we say: “the bucket has nothing in it” we mean that it is not carrying anything like water, dirt, garbage, etc.  However, the bucket still has air in it so if we use an absolute sense of the word “nothing” we must say that the bucket has something (air) in it.

What if we remove all the air in our bucket and just have empty space?  As Krauss points out this empty space will still occasionally be filled with fields that have the potential to spontaneously create particles.  Thus, Albert will say that our bucket is still not empty because of this ability for particles to be spontaneously created.  What then would we need to do for the bucket to be full of actual “nothingness?”  To be honest I don’t know.  In fact I don’t think anyone knows because there is no way we can define nothing in this sense.

Let’s hypothetically imagine what we would need to say there is absolutely nothing in the bucket.  First there would have to be no potential for particles to be created.  Next, let us wonder whether we could fill the bucket with water.  What happens when water hits the space filled with nothing.  Does the water just disappear because there is nothing there or does the water take over the space that was previously nothing?  This creates a problem; if water can go into the bucket then we can’t say there was nothing there.  The ability to fill the bucket means that the nothingness had a size and shape that could be replaced with water and that it also had some sort of properties that let it be replaced by water.  The problem still exists if the water disappears when it touches the nothingness.  If something disappears when it hits nothing then the nothing has the property of removing physical things like water and thus it is really something rather than nothing.

The point I am trying to get to is that the idea of absolute “nothing” doesn’t really make sense; this is what Albert should have realized when he wrote his book review.  The word “nothing” when used in the debate of how the universe arose from nothing is really just a placeholder.  Nothingness refers to those things that we do not yet understand and perhaps will never understand.

To explain my claim that “nothing” is a placeholder let’s use an example.  Let’s say that there was nothing before the big bang.  If you think about it we don’t really mean absolute nothing.  What we really mean is we do not understand what there was before the big bang.  Because something must have existed that had the potential to turn into our universe.  This is what I mean when I say “nothing” is a placeholder for those things we do not understand.

In the past people said that an empty bucket had “nothing” in it.  We solved that mystery and learned that it was full of air.  People have also said that empty space is nothing.  But we now know that even empty space not only has the ability to be filled with objects but also that particles can spontaneously arise in this empty space.  Our previous use of the word nothing was a placeholder we used to explain what appeared empty to us but that we now know is not empty at all.

Now to return to Albert’s criticism of Krauss.  Albert criticizes Krauss for claiming that physics may have explained how something came from nothing.  In a sense they are both correct.  Krauss correctly points out that modern science might be able to explain how our universe could arise from empty space.  If we are gracious to Albert and accept his definition of nothing we can say he is also correct.  Albert points out that the potential to become something is actually something itself and thus Krauss’s nothing was never really nothing.  But remember, our universe does exist so whatever came before our universe had the potential to become something, thus there was never really nothing.  Thus Albert’s problem is that he has just defined nothingness out of existence.

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