Tag Archives: physics

What Are the Limits of Physics?

Contrary to the disciples of scientism, physics has limits. Philosopher Ed Feser gives a quick run-down which is worth passing along. Feser writes,

As I have emphasized many times, what physics gives us is a description of the mathematical structure of physical reality.  It abstracts from any aspect of reality which cannot be captured via its exclusively quantitative methods. (emphasis added)

Let’s stop here because this is important. What Feser is saying is that when the methods of physics are applied to any object, any event, any piece of the world around us, the method only addresses the parts of that object, event, or piece of the world that can be mathematically quantified. Physics ignores any parts of the world that cannot be mathematically quantified.

One reason that this is crucial to keep in mind is that from the fact that something doesn’t show up in the description physics gives us, it doesn’t follow that it isn’t there in the physical world.  This is like concluding from the fact that color doesn’t show up in a black and white pen and ink drawing of a banana that bananas must not really be yellow.

In both cases the absence is an artifact of the method employed, and has nothing whatsoever to do with the reality the method is being used to represent.  The method of representing an object using black ink on white paper will necessarily leave out color even if it is there, and the method of representing physical reality using exclusively mathematical language will necessarily leave out any aspect of physical reality which is not reducible to the quantitative, even if such aspects are there.

But maybe all of reality is just composed of mathematical structure. Feser argues that this cannot be the case, that other aspects of reality must be there.

The quantitative description physics gives us is essentially a description of mathematical structure.  But mathematical structure by itself is a mere abstraction.  It cannot be all there is, because structure presupposes something concrete which has the structure.  Indeed, physics itself tells us that the abstraction cannot be all there is, since it tells us that some abstract mathematical structures do not fit the actual, concrete material world.

For example, Einstein is commonly taken to have shown that our world is not really Euclidean.  This could only be true if there is some concrete reality that instantiates a non-Euclidean abstract structure rather than a Euclidean abstract structure.  So, physics itself implies that there must be more to the world than the abstract structure it captures in its purely mathematical description, but it does not and cannot tell us exactly what this concrete reality is like.

Physics is one tool, a powerful one certainly, in our toolbox for describing reality. But to think that it is the only tool in the toolbox is just silly.

Can the Mind Be Explained by Physics?

Post Author: Bill Pratt

Some naturalists are betting on it, because ultimately physical laws, in their worldview, have to explain everything.  For the naturalist, there is nothing but physical reality which is governed by physical laws.  That being the case, everything, including the human mind, must be reduced to the purely physical and mechanistic.

Philosophers have pointed out serious problems with this attempt to reduce the mind to physics.  In a fascinating discussion of the origins of modern science, philosopher Richard Swinburne explains that mental states have been purposefully excluded by scientists because mental states were not seen as anything that science could measure or investigate.  Here is Swinburne:

Thermodynamics was conceived with the laws of temperature exchange; and temperature was supposed to be a property inherent in an object.  The felt hotness of a hot body is indeed qualitatively distinct from particle velocities and collisions.  The reduction was achieved by distinguishing between the underlying cause of the hotness (the motion of the molecules) and the sensations which the motion of molecules cause in observers. . . .  But this reduction has been achieved at the price of separating off the [sensation] from its causes, and only explaining the latter.  All reduction from one science to another dealing with apparently very disparate properties has been achieved by this device of denying that the apparent properties (i.e., the ‘secondary qualities’ of colour, heat, sound, taste, etc.) with which one science dealt belonged to the physical world at all.  It siphoned them off to the world of the mental.

But then, when you come to face the problem of the sensations themselves, you cannot do this.  If you are to explain the sensations themselves, you cannot distinguish between them and their underlying causes and only explain the latter.  In fact the enormous success of science in producing an integrated physico-chemistry has been achieved at the expense of separating off from the physical world colours, smells, and tastes, and regarding them as purely private sensory phenomena.  The very success of science in achieving its vast integrations in physics and chemistry is the very thing which has made apparently impossible any final success in integrating the world of mind into the world of physics.

Swinburne’s point is profound.  Modern science was never meant to deal with the mind and its mental states.  Not only that, but its very avoidance of explaining the mind is what has made it so successful.  Naturalists who demand that science explain the mind are asking it to do the impossible.  Maybe the mind is not reducible to physical laws.  Maybe it’s just the opposite – physical laws are ultimately reducible to The Mind.

Is Hawking’s Theory about the Creation of the Universe New?

Stephen Hawking NASA 50th (200804210002HQ)

Post Author: Bill Pratt

I was discussing Hawking’s recent book with a regular blog commenter who mentioned that Hawking’s ideas on the creation of the universe were new and that he hadn’t had time to look into them.  This got me thinking about whether Hawking really was on to some new formulation of physics that had never been published before.

It turns out the answer is “no,” according to physicist Stephen Barr.  In his article, “Much Ado About ‘Nothing’: Stephen Hawking and the Self-Creating Universe,” he traces the genesis of Hawking’s ideas:

The idea that Hawking is now touting is not new—in fact, within the fast-moving world of modern physics it is fairly old. My first introduction to it was reading a very elegant theoretical paper entitled “Creation of Universes from Nothing,” written in 1982 by the noted cosmologist Alexander Vilenkin, who argued that our universe might have arisen by a “quantum fluctuation.”

This idea is sometimes referred to as the quantum creation of the universe. There are different variants, but the basic idea is well-known among particle physicists and cosmologists.

Barr then proceeds to describe the nature of this theory:

Right up front, it must be noted that this idea is extremely speculative, has not yet been formulated in a mathematically rigorous way, and is unable at this point to make any testable predictions. Indeed, it is very hard to imagine how it could ever be tested. It would be more accurate to call these “scenarios” than theories.

Having said this, though, Barr warns readers not to blindly dismiss the idea of quantum creation.  He explains that it is based on applying quantum mechanics to entire universes.  Although quantum mechanics is well understood at a sub-atomic level, Hawking and others are speculating what quantum mechanics might look like at the level of entire universes.

After expanding upon the theory of quantum creation, Barr ultimately comes to this point:

Perhaps my explanations are not really necessary. Even the most casual readers recognize that the cosmological theories put forward by Hawking do not bear upon larger questions that motivate classical views of creation out of nothing. Non-scientists are quick to ask the obvious questions. Why a system obeying quantum mechanics, M-theory, superstring theory, or whatever laws of physics that make scientific speculations possible in the first place? Why not no system at all, with no laws at all, no anything, just blank non-being?

Let’s put Hawking’s theories in perspective.  What exactly can these theories tell us?

Physics scenarios and theories are merely mathematical stories. They may be fictional or describe some reality. And just as the words of a book by themselves can’t tell you whether it’s fact or fiction—let alone have the power to make the world they describe real—so with the equations of a physics scenario. As Hawking once understood, equations may turn out to be an accurate description of some reality, but cannot not confer reality on the things they describe.

Finally, Barr reminds us:

There are two answers to the question: “Why does anything exist rather than nothing at all?” The atheist answers, “There is no explanation.” The theist replies, God. An intelligent case can be made for either answer. But to say that the laws of physics alone answer it is the purest nonsense—as Hawking himself once realized.

Why is Stephen Hawking Wrong about God?

Post Author: Bill Pratt

In Stephen Hawking’s latest book, The Grand Design (I haven’t read it yet, but I have read Hawking’s introduction and pre-release interviews), he offers explanations as to why our universe exists and why there is such incredible fine tuning in our universe to support advanced life on earth.  His answer seems to be that the laws of physics are the explanation.  There is no need for God.

Enter Professor John Lennox.  He wrote an excellent piece recently dealing with Hawking’s claims head on.  Lennox begins:

According to Hawking, the laws of physics, not the will of God, provide the real explanation as to how life on Earth came into being. The Big Bang, he argues, was the inevitable consequence of these laws ‘because there is a law such as gravity, the universe can and will create itself from nothing.’

Unfortunately, while Hawking’s argument is being hailed as controversial and ground-breaking, it is hardly new.

For years, other scientists have made similar claims, maintaining that the awesome, sophisticated creativity of the world around us can be interpreted solely by reference to physical laws such as gravity.

It is a simplistic approach, yet in our secular age it is one that seems to have resonance with a sceptical public.

But, as both a scientist and a Christian, I would say that Hawking’s claim is misguided. He asks us to choose between God and the laws of physics, as if they were necessarily in mutual conflict.

But contrary to what Hawking claims, physical laws can never provide a complete explanation of the universe. Laws themselves do not create anything, they are merely a description of what happens under certain conditions.

Lennox then goes on to further explain the mistake that Hawking is making:

What Hawking appears to have done is to confuse law with agency. His call on us to choose between God and physics is a bit like someone demanding that we choose between aeronautical engineer Sir Frank Whittle and the laws of physics to explain the jet engine.

That is a confusion of category. The laws of physics can explain how the jet engine works, but someone had to build the thing, put in the fuel and start it up. The jet could not have been created without the laws of physics on their own  –  but the task of development and creation needed the genius of Whittle as its agent.

Similarly, the laws of physics could never have actually built the universe. Some agency must have been involved.

To use a simple analogy, Isaac Newton’s laws of motion in themselves never sent a snooker ball racing across the green baize. That can only be done by people using a snooker cue and the actions of their own arms.

The rest of Lennox’s article takes on other aspects of Hawking’s arguments and is well worth reading.

*Another response: Alister McGrath has also written a brilliant article addressing Hawking’s book.

Why Do Scientists Believe the Universe is Almost 14 Billion Years Old? Part 2

Post Author: Bill Pratt

Continuing from the first post on this topic, we will look at two more methods that physicists and astronomers use to determine the age of the universe.  Again, this information has been gathered from Hugh Ross’ A Matter of Days.

The third method physicists use to calculate the age of the universe is to measure the age of stars throughout the universe.  Stars are simple objects, composed of 100% gas, that burn through the process of nuclear fusion, which, according to Ross, is very well understood and experimentally verified.

Because the process of stellar burning is so well understood, the physicist or astronomer can determine the age of a star if he knows the mass, color, and brightness of the star (all characteristics that can be measured from earth).  From this data, the astronomer can know how long the star has been burning, which places a boundary on how old the universe must be (it can’t be any younger than the oldest star).

The fourth method physicists use to calculate the age of the universe is to measure the relative quantities of radioactive isotopes in the universe.  Radioactive isotopes are only produced by supernovae, which are supergiant stars in their last stage of burning.

It turns out that radioactive isotopes decay at rates (half-lives) that are well understood.  Uranium and thorium, for example, have half-lives of billions of years.  Since we still find uranium and thorium in the universe, we know that the universe cannot be so old that these isotopes had completely decayed out of existence.  That sets an upper limit of a few hundred billion years.

On the other hand, those isotopes with half-lives of millions of  years or less (e.g., plutonium, neptunium, technetium) cannot be found on the earth, so we know that at least a billion years have gone by for them to have disappeared.  Since astronomers know how much of these isotopes were produced by ancient supernovae, and they know the decay half-lives, by measuring the amounts of these isotopes in existence today, they can calculate how much time has passed since the first supernovae produced the first isotopes.  Obviously the universe must be older than this.

Summary and Conclusion

I hope you were able to follow, at least at a basic level, these four methods.  Ross claims that there are many other independent methods that have been used to calculate the age of the universe, but that these four are the most simple for lay people to understand.  What strikes me about these methods is that they rely on different and independent measurement techniques, but they all arrive at the same answer for the age of the universe – around 13.7 billion years.

It’s easy to attack one measurement technique as being inaccurate, but when four independent methods give you the same answer, you need to pay attention.  And remember, it’s actually more than 4 techniques.  The laws of physics used to date the universe are very well understood and experimentally verified to a great degree of precision.  To dismiss all of these independent measurements as erroneous betrays a lack of understanding of physics and mathematics.

If you find yourself still questioning these findings, ask yourself why.  The age of the universe does not at all undermine Scripture.  Whether the universe is 13.7 billion years old or 6,000 years old has no bearing on the truths taught in the Bible.  As Christians, we are to seek out the truth, no matter what it may be.  The true findings of science will never the contradict the Word of God, so engage with science and enjoy the discoveries that lie ahead of us.  We have nothing to fear!!

Why Do Scientists Believe the Universe is Almost 14 Billion Years Old? Part 1

Post Author: Bill Pratt

Some in the evangelical community dismiss the science that shows the universe is old (almost 14 billion years), and I think partly because they never considered the reasons why scientists make this claim.

I am not a physicist or an astronomer, but I am an electrical engineer, so I had to take physics classes in college and gain an understanding of physics in order to practice electrical engineering.  I am going to present some reasons the universe is old, but I cannot get into the details of it.  These reasons are taken from Hugh Ross’ book, A Matter of Days.  I am hoping that this post, and the next, will spur some of you to do more research on the topic.

The first method physicists use to calculate the age of the universe is to measure the expansion rate of the universe.  The universe is growing larger (like a balloon expanding by someone blowing into it), and if we can measure at what rate it is growing, we can calculate how long ago the universe came into existence.  We can mathematically reverse the expansion until the universe reverts back to a singularity, a point so small the human eye cannot detect it.  This is the beginning of the universe.

The way the expansion is calculated is by measuring the distance from other galaxies to us, and observing how fast these other galaxies are moving away from us.  If we know the distances and velocities of enough galaxies, we can calculate the expansion rate of the universe, and thus the age of the universe.

The second method physicists use to calculate the age of the universe is to measure the cosmic background radiation temperature.  When the universe came into existence, it generated a lot of heat!  Ever since that creation event, the universe has been cooling down as it ages.

When we measure the cosmic background radiation (“take the temperature” of the universe), the readings indicate that the temperatures all around us are about -455 deg F (only 2.725 deg C above absolute zero) and vary little – less than 1 part in 10,000.  Given the geometry of the universe and these temperature readings, physicists can calculate how long the universe has been cooling, and thus the age of the universe.

In the next post, we will look at two more methods for determining the age of the universe.  I hope you’ll stick around to learn about them.