The beauty of physics is that it can rigorously predict things nobody has seen before, before the emergence of any empirical evidence. Compare to fraudulent fields like psychology that overfit from naive "empirical evidence" to predict nothing.

When Physicists speak of "beauty" in their theories, they really mean that their theory possesses at least two essential features: 1. A unifying symmetry 2. The ability to explain vast amounts of experimental data with the most economical mathematical expressions.

Physics is the ultimate intellectual adventure, the quest to understand the deepest mysteries of our Universe. Physics doesn’t take something fascinating and make it boring. Rather, it helps us see more clearly, adding to the beauty and wonder of the world around us. When I bike to work in the fall, I see beauty in the trees tinged with red, orange and gold. But seeing these trees through the lens of physics reveals even more beauty.

To the scientist, the universality of physical laws makes the cosmos a marvelously simple place. By comparison, human nature—the psychologist’s domain—is infinitely more daunting. In America, local school boards vote on subjects to be taught in the classroom. In some cases, votes are cast according to the whims of cultural, political, or religious tides. Around the world, varying belief systems lead to political differences that are not always resolved peacefully. The power and beauty of physical laws is that they apply everywhere, whether or not you choose to believe in them.
In other words, after the laws of physics, everything else is opinion.

A physical law must possess mathematical beauty

Physics is awesome... because the same patterns are universal... in the kitchen and in the furthest reaches of the universe.

Physicists describe the two properties of physical laws—that they do not depend on when or where you use them—as symmetries of nature. By this usage physicists mean that nature treats every moment in time and every location in space identically—symmetrically—by ensuring that the same fundamental laws are in operation. Much in the same manner that they affect art and music, such symmetries are deeply satisfying; they highlight an order and coherence in the workings of nature. The elegance of rich, complex, and diverse phenomena emerging from a simple set of universal laws is at least part of what physicists mean when they invoke the term "beautiful."

General relativity is certainly a very beautiful theory, but how does one judge the elegance of physical theories generally?

... now I know that physics is about uncovering the reality behind appearances. It's about glimpsing this deep and hidden architecture of existence itself. It's about embracing that the world is not what it seems and that everything is stranger and simpler than we can imagine, and yet comprehensible.

Our attraction to that quality which we have come to call 'beauty', and which we associate with the detection of innate unity and harmony in the face of superficial diversity, has led us to expect that the unity of the Universe should be expressed in certain particular ways. If we are physicists we might often hear talk of the 'beauty' or 'elegance' of particular ideas or theories to such an extent that, like Dirac, *we make aesthetic quality a guide or even a prerequisite for the formulation of correct mathematical theories of nature.

Suppose the apprehension of beauty is itself a way to truth? Suppose that “elegance” — as the word is used by physicists to describe their discoveries — is a key to ultimate reality?

[W]hat I had been missing... and what Feynman realized: physics is the ultimate intellectual adventure, the quest to understand the deepest mysteries of our Universe. ...[I]t makes us see more clearly, adding to the beauty and wonder of the world ...[T]he lens of physics adds more beauty to the world ...

It is the great beauty of our science, chemistry, that advancement in it, whether in a degree great or small, instead of exhausting the subjects of research, opens the doors to further and more abundant knowledge, overflowing with beauty and utility.

Bacon in his instruction tells us that the scientific student ought not to be as the ant, who gathers merely, nor as the spider who spins from her own bowels, but rather as the bee who both gathers and produces. All this is true of the teaching afforded by any part of physical science. Electricity is often called wonderful, beautiful; but it is so only in common with the other forces of nature. The beauty of electricity or of any other force is not that the power is mysterious, and unexpected, touching every sense at unawares in turn, but that it is under law, and that the taught intellect can even now govern it largely.