In physics you have four fundamental forces and four fundamental dimensions and two fundamental types of stuff with associated properties and fates. In each case you have something, the odd one out – the one that is not symmetrical – the jokers in the physics deck.
Continued from yesterday’s blog…
4) What are the relationships between the three jokers?
Recall that there’s gravity (which refuses to be unified with the other three forces of nature); time (which carries you along for a wild and woolly one-way ride whether you like it or not); and entropy (which in the final analysis is going to make a real irreversible mess out of you).
*Gravity [+] Time: This is a lopsided, unidirectional relationship. Einstein’s General Theory of Relativity tells us that the higher the gravitational field, the slower time passes. So, clocks at the surface of the Earth will tick-tock ever slightly more slowly than identical clocks that are on the Moon which has lesser gravity relative to the Earth. However, the passage of time influences gravity not a bit. Gravity gets neither stronger nor weaker with the passage of time.
*Gravity [+] Entropy: Gravity has no apparent broad-brush effect on the natural decay of the Universe from order to disorder. Entropy in turn can’t affect gravity because gravity itself just is; it has no more or less order today than it did yesterday. However, when gravity becomes extreme, say when you form a Black Hole, what you get in the centre, the heart of a Black Hole, is a singularity which is about as uniform a bit of stuff as you are ever likely to encounter. Well, uniformity is in fact the highest state of entropy – maximum disorder – that you can obtain. You can’t get more disordered than something which is 100% uniform, for example like the ultimate ‘Heat Death’ of the Universe referred to above. A singularity has no structure, no architecture, and no distinguishing features that can further degrade into something even more disordered and bland.
*Time [+] Entropy: Time flows in one direction; entropy flows in one direction. However, in some cases, one can change the direction of a small bit of entropy albeit while adding to its general unidirectional flow in a broader context. For example, one can assemble a jigsaw puzzle, going from an initial disordered state to a more ordered state. However, that’s at the expense of energy expenditure on your part, ordered energy that has been transferred now into energy (of heat, movement, etc.) that’s no longer available to you after-the-fact – an overall increase in the disorder of the Universe even if a small part of the Universe, the completed jigsaw puzzle, has locally reversed the general trend. That’s not a trade-off that’s possible with time. You can’t grow a bit younger at the expense of making something else grow a bit older a bit faster.
5) So which one (if any) is the greatest joker of them all?
*Gravity is weird. Unlike say electromagnetism, you can’t shield yourself off from gravity – there’s no barrier you can put between yourself and gravity (and thus help reduce the daily wear and tear on your body or improve your athletic skills). Since its range is infinite, there’s no escape. However, it does drop off in intensity via the inverse square law relationship. That is, if you go twice as far away from the source, the force is one quarter of what it was. If you go three times farther away, the force is but one-ninth; four times farther away, one-sixteenth, and so on. You can also ‘cheat’ gravity by living on a lower gravity object, like our Moon (one-sixth Earth’s gravity) or on an asteroid. Even though gravity dominates the entire Universe; holds stars and solar systems and galaxies even clusters of galaxies together in its embrace, and even though there’s no shield that cuts it off, if you hate gravity that much, there’s a solution. You of course could just fall in gravity’s well of attraction indefinitely, and as long as you’re falling, you don’t experience or feel any gravity. You are weightless. Translated, go into orbit and experience Zero-G. Orbiting is just indefinite freefall under gravity’s unrelenting pull. Or, one can seek out the gravitational equilibrium point between two high gravity objects where the gravity of the one matches the gravity of the other. For example, there’s a point between the Earth and the Moon where the gravitational attraction of the one equals and balances the attraction of the other. However, this is only a quasi-solution because there are lots of other objects also coming and going and orbiting around and their ever shifting locations and their gravity disturbs that otherwise pristine point that would exist for all eternity if just those two objects existed. Alas, life’s not that simple. Still, to a first approximation, it’s a solution for gravity haters.
However, gravity probably isn’t the ultimate joker in the physics deck. That’s because there does appear to be at least a quasi-symmetrical counterpart, an ‘antigravity’ of sorts, called “dark energy” (or “funny energy”), also known or related to Einstein’s Cosmological Constant (revisited); quintessence; or quantum fluctuations. Dark energy is a repulsive force that is apparently causing the expansion of the Universe, contrary to commonsense, to ever accelerate. Also, physicists are 100% convinced that gravity can be, ultimately must be, unified with the other three forces. There is no logical way, it is in fact unthinkable, that there are two sets of software running the cosmos, unless of course the cosmos we think of as real is just a simulated, virtual reality universe that resides on someone’s (or something’s) super-computer.
*Entropy is not quite the ultimate joker either since local pockets of entropy can be reversed at the expense of increasing entropy outside of that local pocket. Your life and activities are one constant battle trying to reverse local entropy, but all that is at the expense of increasing entropy (via expending your store of energy) in the broader arena called the cosmos. You’ll win all the battles, except the last, but those local reversals were fun while they lasted.
*Time is the ultimate joker in that it’s unidirectional everywhere for everyone and despite all the speculation about physics allowing time travel to the past, well there really does appear to be, in astrophysicist Stephen Hawking’s phraseology, a “Chronology Protection Conjecture” making the Universe safe for historians. Apart from that, we just don’t see time travellers from the future coming around to gawk at their primitive ancestors.
But even if you could go back in time, it achieves nothing for you personally. Time travel to the past, even if possible and when postulated in the popular or technical literature, you don’t anti-age. If you time travel back to the year of your birth, you don’t revert back to being a baby again. You still retain your before-the-fact actual chronological age, and you just keep on ageing, ever ageing at one second per second.
Now time, rate-of-change can slow down for someone undergoing high and constant acceleration and/or being in the presence of or experiencing a very high gravitational environment. That was postulated by Albert Einstein and has since been experimentally verified many times over. The fly in the ointment is that the slowing down of time, the slowing down of rate-of-change, is only from the point of view of an external observer. The person undergoing the acceleration, or experiencing a high gravitational field, still notes their own personal time ticking away at the usual rate of one second per second.
Time is absolutely the one thing in physics you have no control over. Nothing you do will ever alter your personal rate-of-change (ageing) at that rate of one second per second. And that’s the unfortunate bottom line.
In conclusion from this little, admittedly layman’s analysis, you can escape (even if not shield yourself from) gravity’s joker; you can reverse your local entropy joker; but you are absolutely powerless against the ultimate joker, time.
I’m not entirely sure what the actual significance of any of this is, but if there is none, that still leaves behind some rather amazing asymmetrical facets that’s part and parcel of our Universe. However, as we’ve seen, the trio of jokers have relationships between them (time and entropy are obviously connected; ditto gravity and time; and gravity can freeze entropy at say a singularity that lies at the heart of a Black Hole). Ultimately there’s still a lot yet to be learned about the nature of gravity, entropy and especially time, and why these pieces of the cosmic jigsaw don’t seem to fit all that neatly into the overall puzzle due to their asymmetrical relationships within that broader cosmic context.
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