Physics and Theology provide paths for understanding reality.<1> Neither one is complete but both provide helpful insights. Ironically, they both uncover deep mysteries, too. In this post I explain some of the mysteries uncovered by physics.
Before 1905 everyone knew that time was universal. If everyone synchronized their clocks they would agree forever.
Everyone knew that three dimensional space extended to infinity. If everyone used identical measuring rods they would always agree on the location of every object.
Everyone knew the universe did not expand or contract. The planets moved in orbits around the Sun, but the stars were fixed.
Before 1905 everyone knew the equations of physics could be used to calculate precise results for the motion of any number of physical objects, for example billiard balls, even if they bumped into each-other.
We knew these things because of the amazing success of Sir Isaac Newton's theories. His book, Mathematical Principles of Natural Philosophy, published in 1687, accurately described the motion of all material objects, even when they collide with others. He invented calculus which, when combined with his theory of gravity, explained not only the arc of a cannon ball flying through air, but also the orbits of the planets around the Sun.
Problems with these theories did emerge. Experiments, starting in 1887, demonstrated that the speed of light was the same no matter what the speed of the person making the measurement. This violated Newton's theories and common sense. For example, if you are running toward a tennis ball at ten miles per hour, and the tennis ball was served toward you at thirty miles per hour, you will measure its speed as forty miles per hour relative to yourself. That is not the case for the speed of light. Even if you are moving toward a source of light at half the speed of light, you will still measure the speed of that light as the same as if you were standing still. How can that be?
That is the question Albert Einstein sought to answer. In 1905 he astonished the world of physics with his solution. His paper, On the Electrodynamics of Moving Bodies, is now known as Special Relativity. It combined space and time into four dimensional space-time. According to Einstein, two people will make different measurements of both space and time, unless they are stationary with respect to each other. But they always measure the same speed of light, no matter what their relative speeds might be.
Special Relativity claims no signal or force can travel faster than light. Isaac Newton's theory of gravity violated this prediction. According to Newton the gravitational force between two objects depended only on their mass and the distance between them. For example, gravity pulls the Earth and our Moon toward each other. According to Newtonian gravity, at each instant of time that mutual pull is in a direct line between them. However, on average the Moon is 1.27 light seconds from the Earth. When we look at the Moon, we see it where it was 1.27 seconds ago, not where it is right now. So, is gravity pulling us toward where the Moon is now, or toward where we see it now?
In 1915 Einstein proposed a solution in, The Field Equations of Gravitation. In it he explained gravity as a curvature in the four dimensional space-time which he had discovered only ten years earlier. The new theory is called General Relativity because it extends Special Relativity. The picture above visualizes space-time curvature as depressions in the grid of space-time around massive objects. Imagine the central green object is moving. The dimple in space-time it creates moves too, but the central part moves sooner than the distant parts. It is similar to moving your finger on the surface of water. Your finger makes a dimple and the movement creates ripples. Massive objects moving in space-time also create ripples. Those ripples are called gravity waves.
According to General Relativity, gravity waves move at the speed of light. So, if Einstein is right, the Moon is pulling on the Earth in a direct line to where we see the Moon, not to where it is at the present time, as Newton thought.
For ordinary speeds and distances Isaac Newton's theory works well enough. For higher speeds and longer distances the greater accuracy of General Relativity is needed. GPS satellites use it to provide accurate information. General Relativity explains our expanding universe, the apparent existence of black holes, and numerous other strange phenomena.
Still there were unanswered questions. Starting in 1877 several experiments showed that atoms could emit and absorb only certain wavelengths of light. Nothing in physics could explain it, including Einstein's relativity theories. Niels Bohr partially explained it in 1913. Albert Einstein contributed ideas too. In 1926 Erwin Schrödinger published a new equation that did explain these observations. That theory is now called Quantum Mechanics.
Quantum Mechanics is more surprising than General Relativity. Solutions to quantum equations are probability wave functions. To be specific, consider an experiment with two electron detectors, A and B, such that Quantum Mechanics gives an equal probability of the electron being found at detector A or B. A single electron will be found at A or at B, but never at both. A million electrons will trigger each detector very close to half a million times. The natural conclusion is that each electron took either the path to A or the path to B, but, that is not correct. According to Quantum Mechanics every electron took the same path, so diffuse that it covers both detectors. How mysterious and odd that idea is.
How can this be reconciled? When an electron is detected at A or B, its "waveform collapses." It collapses into a single value, and triggers one of the two detectors. From the point of view of Quantum Mechanics this is a magical transition. This magical transition out of the quantum description to something we can measure is the only way Quantum Mechanics can be verified. Every attempt to recast Quantum Mechanics into a more sensible and expected theory has failed.
This situation is so odd that many interpretations of Quantum Mechanics have been proposed. Each of them has defenders, but they are all conjectures, not established facts. There is nothing in Quantum Mechanics or any other theory that can answer the questions. In practice, people do not think about what they are doing or why it works. They simply make the required calculations and get a prediction. In all cases tested so far, the prediction turns out to be correct.
We now have two theories, each verified by numerous careful experiments, each still being tested, and each proved correct in all cases. General Relativity describes the behavior of large objects. Quantum Mechanics describes the behavior of very small objects. Despite nearly a century of trying, nobody has found a way to combine these two theories. Is it possible to combine them? We do not know.
In the old physics of Isaac Newton, we thought we knew what we were talking about. Roll the white billiard ball across the table to strike the black one, and compute the result. Quantum Mechanics describes these objects as mostly empty space. Electrons form clouds around the dense nucleus of each atom. As far as we know electrons are simple, not composed of other smaller particles. But what is an electron? The answer from physics is circular. An electron is the thing that behaves the way our equations describe an electron.
General Relativity describes large objects, so maybe it is more definitive? No, it is not. It gives us the famous equation E = Mc2 (Energy = Mass times the square of the speed of light.) The mass of an object is a convenient way to describe its total energy. This is true for large as well as small objects. A rock on Earth may be three billion years old. At the most elementary level what is that rock? It is a bundle of energy. So is the light reaching us from the Sun. Physics reduces everything to energy, but with different appearances to us.
Despite its highly accurate description of the material universe, the physics from 1905 onward leaves us feeling empty and full of questions:
- What are these material things?
- Why do they exist?
- I am composed of these things. What am I?
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- https://www.PrincipledThinking.com/Article/Convergence