Unanticipated Discoveries in Science
FEST log
Entry #007
May 10, 2024
The mystery of gravity
In the previous entry I presented a short narrative of the first three centuries of natural science, the science of matter. The two highlights of radically new theory formation were Newton's laws of motion and of universal gravity, and Einstein's special and general relativity theories. I described how Newton unified the dynamics of Aristotle's separate views of Earthly and celestial phenomena, and how Einstein unified space and time, as well as matter and energy, according to special relativity.
In addition, I mentioned how general relativity is even weirder and its results were even more unexpected. It completely changed our view of what gravity *is*. Let me repeat in more detail the fact-of-the-matter description I gave in entry #006, to try and convey more of a sense of the enormity of the revolution implicit in general relativity. In short: while gravity was seen and felt as a force by Newton, albeit a mysterious force acting at a distance, suddenly it was no longer considered a force in its own right. Rather, the status of gravity was relegated to a side effect.
A side effect of what? Something even more powerful than the crushing forces of gravity that are everywhere and govern anything in the Universe? What could that possibly be?
Spacetime, it turned out.
The mysteries of space and time
Long seen as non-physical and non-substantial, space as an ungraspable empty stage or container for anything physical, was discovered by Einstein as conspiring with time, the equally non-physical and non-substantial inexorable whatever-it-is that seems to let us age and that makes motion in space possible.
Both pure potential, three-dimensional space allows objects to be, and one-dimensional time allows objects to change. Philosophically the two can be classified as innocently sounding abstract concepts called "conditions of possibility". Space and time are the two enabling somethings for anything to happen. Or more accurately some-non-things enabling any-thing to happen.
When space and time present themselves as a carefully woven four-dimensional unity, mathematically defined as a differentiable four-dimensional pseudo-Riemannian manifold, voilà, we can make an accurate representation of the world we live in.
When you live and move in a dynamical four-dimensional spacetime, its curvature prevents you from going in a straight line. Why? Well, you just can't draw a really straight line on a curved surface.
Gravity without gravity
Generalized to a 3-dimensional non-flat space or 4-dimensional non-flat spacetime, the same is true: there just aren't any straight lines. The best you can do is move on a line that is as straight as possible, but still a minimally curved line. That is the closest you can get to Newton's law of inertia in a space with no masses and hence no gravity. In that case Newton tells you that you will move in a straight line if there are no other forces acting on you.
When there are masses, Einstein offers a precise description of how those masses curve spacetime. Having mapped out the bumpy terrain around you, it becomes possible to translate the side effects of traveling in that uneven environment as if there was a mysterious force called gravity, acting on you.
It is those side effects that toss and turn you as in a car on a bumpy road. Moving in a spaceship through the solar system, for example, the Sun warps spacetime like a giant pothole, while each planet adds its own bump to the spacetime scenery -- all in 4-D, mind you, the mathematics of it takes a while to get familiar with. Even so, gravity is benign, in that it still makes your journey as straight and undisturbed as can be, given the world you happen to live in.
As John Wheeler, the greatest popularizer of complex physics in simple terms of the second half of the 20th century, expressed it: the result is "gravity without gravity". Just think about it. The gravity that you feel while reading this, sitting, standing, or lying down, is a constant reminder that you are traveling through space and time. You came into this world inside a bumpy background of four dimensions, partly acting as a space-like container, partly acting like a time-like one-way conveyor belt. Neither space-as-such or time-as-such, but an extremely complex four-dimensional unification of space-like and time-like properties, producing gravity as a side effect.
Who could have thought?
However, gravity without gravity, while presenting itself as a deep mystery, was only one in a series of mysteries, unveiled by science during the last few centuries. Each of those came as a complete surprise.
An early surprise: universal gravity
The whole history of physics, and of science in general, is one of discovering mysteries in ways that, time and again, no scientist had anticipated, or could have anticipated, given what they knew. But given that physics is the simplest, and hence also the oldest, of disciplines in modern science, let us start with physics.
Where did modern science start? One milestone was reached by Copernicus, who placed the Sun in the center of the planetary system, rather than the Earth. But he was not the first to do so. Aristarchus, some eighteen centuries earlier, had proposed the same swap on the chessboard of the solar system. The idea behind what is often called the Copernican revolution, was indeed revolutionary, but not in itself completely original.
In contrast, what was totally unanticipated was Newton's proposal that the laws of motion as well as the law of gravity applied exactly in the same way on Earth as well as among the heavenly bodies: the Moon, planets, moons of planets and comets. The idea of universal gravity was shockingly new: one concept governed by one simple equation, telling us that the strength of gravity falls off as the inverse square of distance.
A 19th century surprise: the role of atoms
Philosophers in different cultures had speculated that matter consists of atoms. This is not surprising, really, given that it was the most conservative choice. The alternative would have been to imagine that matter can be divided infinitely often, which is harder to imagine than the presence of a finite limit to divisibility.
What was really surprising, and could have hardly been guessed, is that real atoms turned out not to carry properties like earth, water, air or fire, as had been generally assumed. Unlike the lucky guesses of ancient philosophers, we learned that a single type of atom or molecule, like H2O, can behave as a solid, liquid, gas, or even plasma when ionized into H and O atoms, solely depending on pressure and density. It was the 19th century theory of thermodynamics that made this clear.
Nobody had guessed that those four phases, as physicists call them, did not reflect built-in properties of atoms, but rather processes between large aggregates of atoms. And even more surprising, those starkly different phases can spontaneously appear whenever we turn up a single dial, for example temperature.
More unpredictable surprises in the science of matter
We have just seen three surprises that for all intents and purposes can be classified as unpredictable: Newton's universal gravity, the atomic nature of matter as producing phenomenology through processes rather than properties, and Einstein's gravity without gravity.
The list goes on. Maxwell discovered that light is a wavelike phenomenon, and naturally he assumed that light would consist of waves in a medium, which he called aether. But he was wrong, as again Einstein showed, in his special theory or relativity. No medium could possibly have the characteristics necessary to produce light or any electromagnetic radiation obeying Maxwell's equations.
Practically speaking nobody could have predicted that yes, light behaves like a wave, but no, not in any kind of medium to make waves in. Or, alternatively, if it were a medium, it was not any medium in space that showed waves happening in time. And it would not have any mass. It would literally be an empty medium, which is why it was dropped as unnecessary.
Other totally unanticipated surprises would follow in rapid succession, during the twentieth century. Quantum mechanics was and is the most mysterious of all, definitely not predicted or even conjectured in any way. That nuclear processes can provide a million times more energy than chemical processes in the same amount of fuel, similarly was unimaginable, until it was discovered and used, for better and for much worse.
Art and science: different goals, similar creativity
Artists desperately want to be original, adding to what has already been produced by humanity in new and ever more creative ways. Scientists, on the contrary, desperately want to avoid unnecessary originality. They want to discover more of the depths of the nature of reality. Peering deeper into how the world of matter works is the holy grail, and the simpler the theories and explanations, the better.
In science, flamboyant and highly original ideas as such are not valued at all. On the contrary, those will be either just ignored, or attacked in the most critical ways to see whether and where they fail. Only if a new theory holds up in a variety of experiments, will it become a candidate for acceptance over time.
Yet, against all their intentions, over the last few centuries scientists have been producing the most stunningly original and totally unanticipated ideas humanity has ever stumbled upon and verified in objective, more accurately intersubjective, ways.
Science as a multigenerational enterprise
The eighteenth century came and went, and so did the nineteenth century. During all that time, while the world changed dramatically, for a large part through enormous advances in science and technology, one thing did not change: the dogmatic scientific belief in viewing the material world as a mechanism, and by extension the whole of reality. How could that finally come to an end? Protesting artists were ignored, as we saw in section "After Newton" in entry #006 in this log. It was only when scientists were forced, kicking and screaming, to accept that, no, reality is not at all like a clockwork or whatever mechanism it was believed to be like.
The greatest thing about science is that they *did* eventually change their minds, by their own lights, in decisions made collectively as a self-governing group of peers. In entry #001, I listed this as the fourth and last characteristic of science, when I wrote: "The above four aspects, theory, experiment, working hypotheses and peer review, are absolutely essential for an area to deserve recognition as a field of science."
Science is a multigenerational enterprise. Sometimes change comes slowly, but when it comes, and is finally generally accepted, there is no turning back. In entry #003 I have described the process as the essence of science being called empirical, within a given accuracy. Also, in entry #006, in the section "Extending validity and accuracy", I have come back to this point while making a plea against hype in presenting novel theories.
In that same entry, in the section "Using science of matter as inspiration", I explained why I was going to make a detour through the history of science of matter, before continuing with our attempt to start up a science of mind. Having reached, for now at least, the end of the detour, in the form of a rich exhibition of mysteries, it is time to take stock of possible lessons that we may have learned, to inspire us in designing new theories and experiments for use in a science of mind.
We will do so in the next entry, where we will return to the theme of entry #005, where we started to experiment with shifts in perspectives on any material object, from seeing it as matter to seeing it as experience to seeing it as appearance. There we will start to explore whether shifts in perspectives on gravity, from Aristotle to Newton to Einstein, may have anything in common with the shifts toward experience, first, and then toward appearance.
– Piet Hut