What are some things that are widely known by physicists but not by laypeople?

Physicists have a profound understanding of certain concepts that are often not widely known or fully appreciated by the general public. One such concept is quantum superposition and entanglement. In quantum mechanics, particles can exist in a state of superposition, meaning they can be in multiple states simultaneously until measured or observed. Additionally, quantum entanglement is a phenomenon where two or more particles become linked in such a way that the state of one immediately influences the state of the other, no matter how far apart they are. These ideas are deeply non-intuitive and challenge classical views of reality, yet they are fundamental to the behavior of particles at the quantum level.

Another area where physicists have specialized knowledge is in the non-intuitive nature of relativity. Einstein's theory of relativity, particularly special relativity, shows that time and space are not absolute but can change depending on the relative speed of observers. For instance, time can slow down, and lengths can contract for objects moving close to the speed of light, a phenomenon known as time dilation and length contraction. General relativity further expands on this by explaining how massive objects like planets and stars curve space-time, leading to what we perceive as gravity. These ideas, while widely accepted in physics, are often misunderstood or not fully grasped by those outside the field.

Physicists are also familiar with the probabilistic nature of quantum mechanics, which is another concept that contrasts sharply with everyday experience. In classical physics, events are generally deterministic, meaning that given enough information, one could predict outcomes with certainty. However, in quantum mechanics, the behavior of particles is governed by probabilities rather than certainties. For example, the position or momentum of a particle can only be described in terms of likelihoods, not exact values, until a measurement is made. This probabilistic framework is a cornerstone of quantum theory, but it can be difficult for laypeople to reconcile with the deterministic world they are used to.

Finally, physicists understand the scale and structure of the universe in ways that are often surprising to non-experts. For example, the concept of dark matter and dark energy, which together make up about 95% of the universe's total mass-energy content, is something that physicists grapple with regularly, yet these ideas remain largely unknown or not well understood by the general public. Additionally, the vast scale of the universe, the billions of galaxies, and the notion that what we see is only a small fraction of what exists are ideas that physicists routinely work with, but these concepts often elude those who are not deeply engaged in the study of cosmology and astrophysics. Null