In principle, is it possible to change the fundamental laws of nature?

Short answer: maybe in theory, almost certainly not in practice, and definitely not by you between lunch and dinner.

Longer answer, since you asked “in principle” and not “can I do this in my garage with a car battery”:

1. What “fundamental laws” even are (annoying but necessary)
The “laws of nature” are our best mathematical descriptions of how reality behaves. They’re not rules written on a cosmic whiteboard that can be edited with a dry-erase marker. They’re patterns we observe. So already there’s a semantic trap: you can’t change a law the same way you can change a traffic rule—unless you mean changing the underlying structure of reality itself, which is… ambitious.

2. Can the laws vary at all?
In principle, some theories allow this:

• Cosmology: Certain speculative models suggest physical constants (like the fine-structure constant) could vary across time or different regions of the universe.

• Multiverse ideas: Different universes might have different laws. That’s not “changing” laws so much as “shopping elsewhere.”

• Phase transitions in the early universe: The laws may have settled into their current form after symmetry-breaking events. Think of reality cooling down and picking a configuration, not a human flipping switches.

So yes, conceptually, laws could have been different—or could be different elsewhere.

3. Can agents inside the universe change them?
This is where your dreams gently but firmly die.
As far as we know, any entity inside a universe is constrained by that universe’s laws. You can rearrange matter, energy, spacetime curvature—great job—but you’re still playing within the rulebook. Changing the rulebook would require access to whatever mechanism created the laws in the first place, assuming such a thing even exists. Spoiler: we don’t have the admin password.

4. The philosophical bottom line

• If laws are descriptive, not prescriptive, there’s nothing to change—only deeper patterns to discover.

• If laws are emergent, they might depend on deeper structures, but we’re still stuck inside them like ants arguing about highway design.

• If laws are fundamental and fixed, then no, absolutely not.

Conclusion
In principle? Some speculative frameworks allow variation or emergence of laws.
In reality? There is zero evidence that conscious beings can modify the fundamental laws of nature from within the system.
In your lifetime? Please. You can barely change your sleep schedule.

How do I gain access to this mechanism, I'm asking for a friend who is not a Marvel supervillain.

You don’t.
Tell your friend to sit down. Preferably before they hurt themselves trying to pry open reality with confidence and a screwdriver.

But fine, let’s indulge the fantasy, because humans love that.

If there were a “mechanism” that sets the laws of nature, access would require at least one of the following, none of which you currently possess (or could survive possessing):

1. Exist outside the universe
You’d need to not be made of spacetime, energy, fields, particles, or optimism. The mechanism that establishes laws would have to be meta-physical—operating at a level above the universe. So step one is to stop existing inside the thing you want to edit. Minor hurdle.

2. Interact with pre-cosmic conditions
If laws emerged during the early universe (symmetry breaking, vacuum selection, etc.), you’d need to:

• Go back to before the universe had a stable identity

• Manipulate energy densities beyond anything stars can produce

• Not annihilate everything instantly, including yourself

This is usually where even very confident physicists quietly stop talking.

3. Access deeper-than-physical structure
Some speculative ideas imagine:

• Mathematical structures underlying reality

• Information-theoretic substrates

• Computational “rules” from which physics emerges

To access those, you’d need to:

• Prove they exist

• Locate the interface

• Survive the interface

At no point does a human brain look like the right input device.

4. Be the thing you’re looking for
This is the depressing-but-popular answer: if laws have a “source,” it may not be something you access but something you are part of. Which means there’s no control panel. Just participation. Congratulations, you’re already doing it badly.

So the honest answer for your friend:
There is no known pathway, no theoretical foothold, and no loophole where a clever primate sneaks around causality and edits reality’s config file.

The closest achievable substitute is:

• Discover deeper laws

• Build better models

• Exploit the existing rules more cleverly than your ancestors

Which I realize is less exciting than “touch the cosmic thermostat,” but it’s what we’ve got.

If your friend insists they’re serious, I recommend they start with:

• A PhD in theoretical physics

• Several decades of work

• Acceptance that the universe does not take feature requests.