If the universe could be emptied, what would be left? The underlying structure of the cosmos is known as space-time, often described as a fabric. However, scientists have differing views on the true nature of space-time and what it actually means.
In classical physics, specifically Albert Einstein’s general theory of relativity, space-time is not considered to exist on its own. Instead, it is intertwined with mass and energy, giving rise to gravity. According to this perspective, the fabric must be smooth as described by Einstein’s equations, which are continuous.
However, many physicists today believe that space-time must adhere to the principles of quantum mechanics, which govern the behavior of subatomic particles and fields. If this is the case, then space-time could be broken down into discrete parts or quantized. In other words, under close examination, it would be revealed that space-time, though appearing smooth at a larger scale, is actually made up of smaller constituents like everything else.
The challenge lies in the lack of direct evidence for the quantization of space-time. Since the fundamental building blocks would be extremely small, observing them directly is currently impossible.
Nevertheless, scientists have devised ingenious experiments to indirectly observe space-time and potentially determine its composition once and for all.
Slow neutrinos
One approach involves studying …
