Changing the Laws of Physics - what would be the results?

Question

A godlike character starts screwing with the laws of physics to demonstrate its terrifying power (and, on a weirder level, to help save the universe from something even worse). But when your resident Eldritch Abomination starts changing the laws of physics, what, exactly, would it look like?

Specifically, what would be the effects of changing Planck's Constant? Rapidly turning off and on the Laws of Motion and Thermodynamics? Slowing down the speed of light to a few thousand miles per hour? Drastically strengthening or weakening the force of gravity?

I'm well aware that this will break the universe (which is actually part of the goal here). But how quickly would screwing with physics like this break things, and what might it break?

You can do whatever you like, thus you can have whatever result you want. — Vincent, Oct 10 '15 at 15:37
Relevant comic from SMBC: http://www.smbc-comics.com/?id=807 — Nzall, Oct 10 '15 at 18:39
Turning the Laws of Thermodynamics on and off? http://i.imgur.com/VGZJg0L.gif — Arturo Torres Sánchez, Oct 10 '15 at 22:51
check out George Gamow's Mr. Tompkins books--they very-simply explain some of the changes you describe — nitsua60, Oct 11 '15 at 01:06

score 21 · Accepted Answer · edited Jun 16 '20 at 11:03

Messing With Constants = Breaking Physics Really Fast

I have a degree in physics. Trust me on this—fiddling with Planck's constant, universal gravitation constant, permittivity of free space, etc. have far reaching effects. As I understand it, this deity can take the laws of physics, the actual things that our equations are modeled on, and change them as it divinely wills. The short answer is that messing with these things can cause unforeseen consequences, so take my answers as a small subset of things which can happen.

Planck's Constant

Planck's constant is fundamentally connected to quantum effects—and thus the effects we see in a human scale! It is common practice in undergraduate QM class to simply scale up masses until it approximates Newtonian mechanics.

Looking at Schrödinger's Equation, and some of the equations derived from it, you can do lots of things, such as knowing the position and velocity of a particle, making photons hit like bullets, teleportation, average radii of atoms, strength of chemical bonds, and in short, just about anything by modifying this constant. Unfortunately, a universal change in this constant would likely result in everything getting destroyed.

Turning On/Off Thermodynamics + Laws of Motion

Infinite energy, perpetual motion, anything could happen. This one is basically a free ticket to do whatever you want.

Speed of Light

Sadly, slowing down the speed of light will not allow other things to exceed it, if Einstein is right. Since the speed of light is the universal speed limit, you can't go faster than it, even if it's going at a snail's pace.

What would happen, though, is that relativistic effects would happen very easily. It would be disorienting, as things are dilating and people disagree when events happen. Humans are not well equipped to handle this sort of experience.

Strengthening/Weakening Gravity

Doing this could:

Throw planets out of alignment
Make buildings crumble (under their own weight)
Quickly form black holes which can very quickly consume everything
Divert missiles, birds, comets, etc.

Perhaps the easiest, and least destroy-everything-right-now option is just to change the gravitational constant for one individual. They'll notice how heavy or light they are, and that may be enough to show off a little without completely destroying everything! This doesn't rule out, of course, people thinking it's just their mind playing tricks on them.

Altering Charges and Masses

The big change here would be in the magnitudes of forces (and energies) related to atom size. Looking at both Newton's law of Gravitation and Coulomb's law, you can see that an increase in mass (or charge) will result in larger forces. Some important impacts from fiddling with these:

Bond Length: Longer bond lengths mean that some previously stable molecules may become unstable.
Orbital Sizes and Transmutation: smaller atom sizes means that electrons could more easily go into the nucleus, resulting in certain types of transmutation for elements.
Density: altering the mass or volume a thing takes up alters its density. This means some things can float, but also some structures couldn't support themselves or be able to support much more.

Reflection/Refraction

Changing how refractive indices work can have some unusual impacts on other things, as you can see by perusing the wikipedia article. Of course, we're not entirely sure if a materials refractive index explains properties of things or if a materials refractive index is explained by properties of things. In any case, messing with this could mean holograms, illusions, and lenses at-will.

Messing with Trig Tables / Functions

If you think math simply describes the world, then messing with these values and functions does nothing. If you think math is inherently in the world, or exists outside of our human minds, then this can mess with the effects of geometry on items. To truly answer this, we really need to determine how math relates to the natural world. Numberphile does a good video outlining this problem.

Upvote for the extremely informative and interesting explanation! Can you explain further how fiddling with some other constants (mass/charge of electron/proton, electromagnetic force related constants, refraction and reflection related constants, trignometric table changes etc) would change/destroy the world? — Youstay Igo, Oct 10 '15 at 17:42
I suppose that this would also likely transform regular minerals into explosives, which could destroy anything on the Earth of what remained (if anything remained) — porton, Oct 20 '15 at 15:30
We have also forgotten to note, that everything would be much heated (and such things as concrete building are likely to melt even if concrete happen to remain hard after orbitals changes). — porton, Oct 20 '15 at 16:24
@YoustayIgo There you go, Youstay! I've addressed some of the things you/others wanted to be addressed. I don't want to add much more, because this is just a peek down the rabbit hole which is the answer to this question. — PipperChip, Oct 21 '15 at 15:54
Now that's a fun read! Can I use this content on my website? Plus I like the lenses at will idea :D — Youstay Igo, Oct 21 '15 at 16:12
@YoustayIgo Thanks for asking permission. I'm okay with it, as long as you follow the provisions set out in the copyright. It seems the content of SE sites are under the Creative Commons Attribution Share Alike License. This means you can use it, but must correctly attribute and distribute content under the same license. http://stackexchange.com/legal — PipperChip, Oct 21 '15 at 16:30

score 11 · Answer 2 · answered Oct 10 '15 at 17:17

To expand on @Vincent's comment, when you start playing with laws of physics, you start to realize how unbearably fragile the things you wanted for your story actually were. As it turns out, life as we know it is remarkably balanced on a razor's edge. The particulars of the path we've taken to get here are intimately entwined with the physical rules that we believe our universe obeys. Making even small changes can have such unbelievably sweeping changes that you won't be able to recognize the life that emerges in such a world. Change those rules mid-reality, like your god wishes to do, and it is almost guaranteed to end in a disaster! The wikipedia page on the Fine-tuned Universe has many great examples of just how exacting the balances need to be for the universe to even resemble what we consider to be reality today. One of the famous examples, is that if you increased the coupling power of the strong nuclear force by just 2%, the entire main-sequence of the stars would change, because hydrogen would fuse into deuterium instead of helium!

If you constrain your god's fancy a bit, there are some neat behaviors that show up in Lagrangian mechanics. Lagrangian mechanics are the fundamental tool used to describe a lot of classical concepts like kinematics. By Nother's theorem every symmetry in a Lagrangian system mathematically defines the existence of something which is conserved. This sounds a bit wishy washy until you look at some of the examples, and realize how profound this is:

If a process is time-invariant, meaning the fundamental physics work the same now as they did a second ago, or a year ago, the conserved value turns out to be energy. Conservation of energy is a natural consequence of the laws of physics working the same at any point in time!
If a process is position independent, meaning the fundamental physics are the same over here as they are over there, the conserved value turns out to be momentum. Conservation of momentum is a natural consequence of the laws of physics working the same at every point in the space.
If a process is orientation independent, meaning the fundamental physics are the same, no matter what direction you claim "up" to be, the conserved value turns out to be angular momentum. Conservation of angular momentum is a natural consequence of the laws of physics working the same, no matter which direction you are facing.

So, if you god is kind enough to limit its activities to things that can be described using normal Lagrangian mechanics, we see interesting effects. If a god wants to disobey the conservation of energy, he/she must have introduced something which is not time-invariant... perhaps its a one time event. If your god wants to disobey the conservation of momentum, he/she must have introduced something which is not position-invariant... perhaps there is a nexus at the core of a deep cave where the rules of physics shift slightly.

It's not quite as much fun as just poking random values into the universal gravitation constant and watching people turn into pancakes, but playing with such limits at least makes it so that the models we have of physics provide interesting and powerful effects.

Upvoted because the "razor's edge" is precisely what this deity is attempting to convey to the universe by destroying everything except a few "lucky" observers, because Langrangian mechanics are a perfect way to describe the way the god usually limits itself, and because the science here is absolutely fascinating. Goodness, I hope to understand all of this someday. Thanks! — Midwinter Sun, Oct 10 '15 at 19:26
What if I have a position independent system that acts like ours except with inertial dampening / friction against vacuum in place? Do I get a non-Lagrangian system, or just momentum that's $mvc^{-t}$ rather than $m*v$? — John Dvorak, Oct 10 '15 at 23:01
@JanDvorak It depends on the particulars. As a general statement, friction like behaviors tend to be dissipation, and dissipative systems are not Lagrangian. In particular, they tend to show path-dependent behaviors which do not show up in Lagrangian mechanics (they use generalized coordinates to avoid a lot of path specific stuff that can be difficult). Newtonian physics doesn't actually fit into modern Lagrangian mechanics because of this. To handle things like friction with Lagrangian mechanics, we have to track things like the kinetic energy from thermal movement of molecules. — Cort Ammon, Oct 11 '15 at 05:07
To get away with inertial dampening and still target Lagrangian mechanics, you'd have to cover questions like "where did the energy/momentum go?" Alternatively, there are some very specific friction like behaviors that do fit directly into Lagrangian mechanics, but their behaviors tend not to be good at describing "inertial damping" — Cort Ammon, Oct 11 '15 at 05:09
It may also be valid to play games with what is conserved, as you suggested with one of your equations. The real key is that something has to be conserved if you want position-invariance. The exact equation for that something depends on the physics of your universe. — Cort Ammon, Oct 11 '15 at 05:12

score 3 · Answer 3 · answered Oct 11 '15 at 05:59

Adding to PipperChip's comprehensive answer, it may be common in SF to "change the speed of light" but really that doesn't make sense. You can't just change the speed of light: look at how the speed is predicted by Maxwell's equations and measured values for magnetic and electrical constants.

If you change the spe3d of light, you affect which atomic orbitals exist, because only standing waves are allowed.

On a deeper level, the speed of light is just a scaling factor. What makes it interesting is how that speed relates to the speed of everyday events like the flight of a mosquito. You define the speed as 1, and measure other things relative to that. So you actually change everything else, not the speed of light!

The things that can actually be fiddled with are the dimensionless constants like "the fine structure constant" and things that as far as we know are arbitrary values like the mass of an electron.

You might try fiddling with changing those things to have the overall result of light moving slower relative to other things and otherwise unchanged, but you'll get into a quagmire fast.

Also, you can speculate about a different universe, but for changing this one in-place, what happens when the overall size scale changes? That is, change the fine structure constant etc. and have atoms be twice as large but seem the same to objects and beings made of them: does it take more space and how do you put the changed system where the old one was?