The world appears solid, fixed, and immovable. A wall is a wall, a window is a window, and the difference between them seems obvious: one blocks vision, the other allows it. Yet upon closer examination—through both modern physics and the teachings of Torah—this certainty begins to dissolve. A wall and a window are, in truth, both made of solid matter. The distinction between opacity and transparency is not absolute; it results from an interaction among the observer, the material, and the nature of light itself. This subtle yet profound idea opens a doorway to a deeper understanding: the world we perceive is not as rigid as it seems, and under the guidance of Torah, a person can refine his perception to the point that even a “wall” can become transparent.

From a scientific perspective, the difference between a wall and a window lies not in their solidity but in how their atoms interact with light. All matter is composed of atoms, and within those atoms are electrons that occupy specific energy levels. These energy levels function like a staircase—fixed and discrete. Light, composed of photons, carries energy in discrete amounts. When a photon encounters a material, it can transfer its energy to electrons. If the energy matches exactly what is needed to move an electron from one level to another, the photon is absorbed. If not, it continues onward.

In materials such as wood, brick, or drywall, the energy levels of electrons closely match those of visible light. As a result, visible light is absorbed almost immediately, making the material appear opaque. Glass, however, is structured differently. Its electrons require much higher energy to transition between levels. Visible light does not have enough energy to be absorbed, so it passes through. The same solid object becomes a “window” rather than a “wall.” In other words, transparency is not the absence of matter—it is a specific relationship between matter and perception.

This leads to an even more striking realization: what we see is only a narrow slice of reality. If human eyes were sensitive to other wavelengths—such as radio waves or X-rays—walls would appear transparent. Indeed, radio waves pass through walls........

© The Times of Israel (Blogs)