- Included in the Stephen Hawking Posts List.
- If you are instead going to hang your hat on scientific determinism, there are many constraints on that concept as well, as I see it.
(Part V)
I found a discussion of scientific determinism in Stephen Hawking’s book Brief Answers to the Big Questions, so I now have a greater understanding of what he is talking about in that regard. As I mentioned in Part III of these posts, Hawking contends that “[t]he basic assumption of science is scientific determinism”. In the chapter optimistically entitled “Can We Predict the Future?”, Hawking talks about the origin of this concept that was built upon foundations laid by Isaac Newton, which “implies that we can predict the future, in principle at least”:
“This led to the idea of scientific determinism, which seems first to have been publicly expressed by the French scientist Pierre-Simon Laplace, but Laplace was rather like Proust in that he wrote sentences of inordinate length and complexity. So I have decided to paraphrase the quotation. In effect what he said was that if at one time we knew the positions and speeds of all the particles in the universe, then we would be able to calculate their behaviour at any other time or place in the past or future.”
I give a counter-example of believing in this kind of determinism in Part III – how keeping track of all of the particles in a closed container of air is obviously unattainable, even on a theoretical basis – that I won’t repeat here. I should point out that the meaning of “particle” to Stephen Hawking might not agree with the way that most of us perceive the term. In an example about escape velocity in the chapter entitled “What Is Inside a Black Hole?”, Hawking begins: “If one fires a particle, such as a cannon ball, vertically upwards . . .”
So, using this more elastic definition of particle, I recognize that the movements and orbits of stars, planets, moons, and similar heavenly bodies can be expressed to an incredible degree of precision. An example is the successful fly-by on New Year’s Day 2019 of the minuscule Kuiper Belt object called Ultima Thule – now known as 486958 Arrokoth – by the NASA space probe New Horizons after it went past the Pluto planetary system. The object turned out to be two planetesimals fused together having an overall length of just 22 miles, and orbiting at a distance of more than 4 trillion miles from the Sun, or over 40 times farther from the Sun than the Earth is. Use whatever analogy you like – that is a staggering feat of astronavigation.
However, the movements of all heavenly bodies are not so set in stone as might be supposed. Besides the planets and moons, our Solar System contains innumerable asteroids, comets, centaurs, etc., with many orbiting near the Earth; from the article on Near-Earth Objects (NEO’s) in Wikipedia: “There are over 30,503 known near-Earth asteroids (NEA’s) and over a hundred known short-period near-Earth comets (NEC’s). A number of solar-orbiting meteoroids were large enough to be tracked in space before striking the Earth.” These NEO’s are small enough that their orbits can be easily affected by planets, moons, the Sun, etc.
The large NEO’s have been reliably tracked by astronomers and do not pose a major threat to Earth. However, even relatively small bodies can create enormous destruction. The best-known recent example is the Tunguska Event, described in Wikipedia as follows: “The Tunguska Event was an approximately 12-megaton explosion that occurred near the Podkamennaya Tunguska River in Yeniseysk Governorate (now Krasnoyarsk Krai), Russia, on the morning of June 30, 1908. The explosion over the sparsely populated Eastern Siberian Taiga flattened an estimated 80 million trees over an area of 2,150 sq. km. (830 sq. mi.) of forest, and eyewitness reports suggest that at least three people may have died in the event.”
More recently, also from Wikipedia, and as shown on a video that has been widely aired throughout the world: “The Chelyabinsk meteor was a superbolide that entered Earth’s atmosphere over the southern Ural region in Russia on 15 February 2013 at about 09:20 YEKT (03:20 UTC). It was caused by an approximately 18 m (59 ft) diameter, 9,100-tonne (10,000-short-ton) near-Earth asteroid entering the atmosphere . . . The asteroid had a total kinetic energy before atmospheric impact equivalent to a blast yield of 400–500 kilotons of TNT (about 1.4–1.8 PJ), estimated from infrasound and seismic measurements. This was 26 to 33 times as much energy as that released from the atomic bomb detonated at Hiroshima.”
Additionally, atomic clocks are often used to measure time when extremely accurate readings are needed. Current atomic clocks using the element cesium are now more accurate in measuring time than the rotation of the Earth itself, requiring occasional adjustments to “official” time by the use of “leap seconds”.
As a further complication, while the equations for calculating gravitational attraction between two heavenly bodies are relatively straightforward, making the same calculations when there are three bodies involved – such as the Sun, the Earth, and the Moon – are virtually impossible, since the calculated movements are often so chaotic and unpredictable. This casts doubt in some instances on the precision of calculations involving their movements. This is known as the “three-body problem” and is described in Wikipedia this way:
“In physics and classical mechanics, the three-body problem is the problem of taking the initial positions and velocities (or momenta) of three point masses and solving for their subsequent motion according to Newton’s laws of motion and Newton’s law of universal gravitation. The three-body problem is a special case of the n-body problem. Unlike two-body problems, no general closed-form solution exists, as the resulting dynamical system is chaotic for most initial conditions, and numerical methods are generally required.”
Another issue, as Stephen Hawking recognizes in his discussion of scientific determinism, is the immense complexity of the calculations that would be necessary to “predict the future”. He summarized the issue as follows: “Do the laws governing the universe allow us to predict exactly what is going to happen to us in the future? The short answer is no, and yes. In principle, the laws allow us to predict the future. But in practice the calculations are often too difficult.”
There is also the principle of chaos, as Hawking explains: “As those who have seen Jurassic Park will know, this means a tiny disturbance in one place can cause a major change in another. A butterfly flapping its wings in Australia can cause rain in Central Park, New York. The trouble is, it is not repeatable. The next time the butterfly flaps its wings, a host of other things will be different, which will also influence the weather. This chaos factor is why weather forecasts can be so unreliable.”
In another part of his book, Stephen Hawking provides a clear discussion of quantum mechanics and the Heisenberg uncertainty principle that omits the counter-intuitive concept that simply having an observer on hand affects the outcome of a scientific experiment: “It was not until 1927 that Werner Heisenberg, another German physicist, pointed out that you couldn’t measure simultaneously both the position and speed of a particle exactly. To see where a particle is, one has to shine light on it. But by Planck’s work one can’t use an arbitrarily small amount of light. One has to use at least one quantum. This will disturb the particle and change its speed in a way that can’t be predicted.”
Finally, Hawking brings up extreme instances of gravity: “The problem arises because gravity can warp space-time so much that there can be regions of space that we can’t observe . . . even in principle”, such as the interiors of black holes.
Scientists and others often ask questions about the Creation like: Did God have any choice about how the Universe was created?; or, What is left for God to do considering how much science now knows about how everything came to be? But if you are instead going to hang your hat on scientific determinism, or some other form of determinism, there are many constraints on that concept as well, as I see it.