Is Physics just the study of the physical world—matter, energy, motion, and the laws that connect them. If we look more closely, that definition already assumes a lot about what exists. Suppose, just for the sake of argument, that the world turns out to be dualistic: that there are both physical and non-physical forms of existence. Would physics still concern itself only with the physical? Or would it have to broaden its reach to remain true to its spirit as the study of all existence?

Imagine a hypothetical scenario where ghosts or unphysical aliens were shown to be real—not in the sense of folklore or belief, but through consistent and intersubjective evidence. In that situation, it would not make much sense to say, “Yes, they exist, we can attest to that, but since they are not made of matter like pendulums or springs, they are outside the realm of physics.” A better, more scientific response would be: “Okay, they exist, we can attest to that—let’s study how they behave under different conditions, carefully.”

The point is: we shouldn’t exclude phenomena based on preconception. We should include whatever reality presents to our experiences, as long as we can study it with rigor. The boundary of physics, then, is not metaphysical—it is methodological. What distinguishes physics (and science in general) is how it studies the world, not what it studies.

Traditionally, physics has been described as the study of what is lawful, measurable, and publicly testable. But even that might be too narrow. In principle, we might encounter phenomena that resist any identifiable law and yet can still be rigorously described and agreed upon through shared observation. So perhaps the most minimal and inclusive definition would be something like this:

This definition doesn’t assume that the universe is orderly, material, or even entirely comprehensible. It only assumes that we can describe what we find honestly, precisely, and in ways others can confirm. Under this view, the “physical” simply means whatever can be shared, examined, and discussed in public terms.

Of course, such a minimal definition must be used responsibly. It should not be a license to wander into the occult or the untestable. The commitment is to disciplined and intersubjectively verifiable description—approached with clarity, completeness, and intellectual honesty—not to speculation for its own sake. Nothing is excluded in principle, but everything is held to the same epistemic standards.

Seen this way, physics becomes not just one branch of science but the root of all scientific inquiry. Every field that studies the world carefully, clearly, and collectively—whether it’s biology, archaeology, or clinical psychology—shares that same spirit. All of them, in their own ways, are physics: the ongoing, honest attempt to describe existence as it truly appears.

The requirements for physics, however, are not merely procedural—they are also moral commitments. Honesty requires that we report what is found, not what we wish to be true. Humility reminds us to recognize the limits of our understanding and methods. Responsibility restrains us from inflating claims or wandering into untestable speculation. Respect for shared experience calls us to value intersubjectivity as a communal form of truth-seeking. In this sense, the definition of physics rests not on metaphysical grounds but on a blend of epistemic and moral ones. Even the epistemic virtues—clarity in concepts and communication, carefulness in method and observation, intersubjective verifiability, and openness to revision—rest upon an ethics of reciprocity. We expect from others the same intellectual honesty we owe to them. It is difficult to imagine any serious academy tolerating someone who ignores these moral obligations. Physics, at its core, is thus both a method of knowing and a moral practice of truthfulness toward the world we share.