The two most prominent hypotheses differ with one another by a factor of one hundred googol quintillion when it comes to attempting to estimate the energy of empty space.
A scientific theory that is successful is one that can produce predictions that are specific and accurate. When two separate theories make predictions that are consistent with one another, it makes the scientific community even happier. Therefore, physicists feel somewhat embarrassed when they employ their two finest theories to forecast the simplest conceivable quantity, and the outcome is that they differ in a manner that is so egregiously significant that it is frequently referred to as “the worst prediction in the history of science.”
Simply said, empty space is just that: empty. Since empty space does not have anything in it, it would seem that calculating its energy would be an easy task, and the prediction would be that it has no value. However, the reality does not live up to that anticipation.
The theory of general relativity and the standard model of particle physics are the two theories that, when combined, serve as the foundation for all of modern physics. The theory of general relativity applies to the enormous structures that can be found throughout the universe and defines the behavior of the force of gravity. In contrast, the standard model of particle physics is applied to the explanation of all other types of forces and is employed to control the quantum world of extremely small things.
Both hypotheses can be tested using zero-g environments. What conclusions can we get from applying these two theories to the problem of determining the energy density of actual vacuum?
The perspective of general relativity
The structure and mobility of space itself are topics that are discussed in Einstein’s theory of general relativity. We have known for over a hundred years that the universe is expanding, and the hypothesis that describes the development of the universe is referred to as the Big Bang theory. In its most basic form, the idea proposes that something started the expansion of the universe when it was much smaller than it is now.
Given that gravity is an attractive force, this suggests that when the expansion began, this expansion would proceed at a more glacial pace given that gravity is an attractive factor. Why? Because every piece of matter in the universe attracts every other piece of matter there is.
As a result, the discovery that was made in 1998 by academics investigating the development of the universe that not only was the universe expanding, but that the expansion was speeding up, came as a very big surprise to everyone. The only way that something like this could occur is if space has a negligible but recognizable amount of energy. If the energy was of the proper kind, the outcome would be a form of gravity that repelled rather than pulled. Researchers refer to this type of repulsive gravity as “dark energy,” and they are able to compute the exact amount of dark energy that is necessary to explain the evolution that has been observed in the universe. This energy is extremely low – it is about comparable to the energy that is released by four hydrogen atoms for every cubic meter of space.
The perspective of quantum mechanics
Therefore, does the standard model anticipate the existence of an energy in space, and if it does, how does it do so?
According to the usual model, every inch of space is packed with an infinite number of fields. When such fields vibrate in particular ways, the particles that make up the quantum universe, such as electrons, quarks, and so on, become visible. However, even when the fields are quiescent, which means they are ostensibly at rest, there is still a continuous residual “hum,” which is characterized by minute transient vibrations in the fields that have a variety of wavelengths. Because in the universe of quantum mechanics, particles and waves are the same thing, this suggests that empty space includes a chaotic mix of ephemeral particles that appear and disappear in what is effectively an instant. The point at which the different fields have the least amount of energy is referred to as the zero point, and the energy that they contain is referred to as “zero-point energy.”
Add up the effects of all the quantum waves to arrive at a calculation of the zero-point energy that exists in the quantum universe. Since there is no theoretically required minimum wavelength, shorter and shorter waves must be added together. Since a short wavelength indicates a high energy level, this indicates accumulating energies of a higher and higher level. Because we know that the normal model eventually breaks down at very high energies, you can only add up energies to a certain maximum (and, thus, only to a certain minimum wavelength). However, if you took this to its logical conclusion, you could add up near-zero wavelengths with near-infinite energy.
The precise value of the maximum energy that should be utilized in the computations is a topic of theoretical debate; nonetheless, the vast majority of scientists agree that the Planck energy is the highest conceivable energy to which the standard model may be applied. If you use that energy as the threshold for your computation, you will find that the energy at the zero-point is significantly more than you expected. The energy density is comparable to having the mass of a hundred quintillion times greater than the entirety of the observable Universe packed into a single cubic meter.
The worst scientific forecast ever
In point of fact, according to this relatively straightforward calculation, the energy density that is anticipated by the standard model is around 10120 times that which is predicted by general relativity. That is a 1, followed by 120 0s in numerical order. This difference unequivocally justifies the moniker of “the worst prediction in the history of science.”
A worst-case situation is represented by the factor 10120. The situation could be improved according to certain unproven suggestions that have been offered. For instance, if a theory known as supersymmetry turns out to be correct, there is “only” a factor of 1060 difference between the two hypotheses.
When there is such a significant gap in opinions, it suggests that either of the two ideas has a serious flaw. It is still possible that our current theoretical understanding is incorrect; nonetheless, general relativity performs a decent job of describing the cosmos, and the standard model does a good job of explaining quantum phenomena. The issue is only brought up when both of these things are contrasted to one another.
Several feasible options
What are some of the potential solutions that have been suggested? To put it simply, there are plenty. For instance, one answer can be derived from the fact that the conventional model presupposes that there is no space that is divisible into smaller and smaller units. This indicates that even the tiniest volume that can be conceived of is capable of being subdivided into even more inconsequential parts in an endless sequence. But what if there is a smaller unit of space? What if there is something that might be thought of as the “atom” of space? If what you say is accurate, then the calculations need to be adjusted, and in that case, the disparity between cosmic energy and quantum energy might no longer exist.
There is also the possibility that our senses have played a trick on us. It may feel as though we are moving through three dimensions of space as we experience the world around us. If there were more than three dimensions of space, then our existing theory of gravity would have to be completely rethought, and the quantum calculations that we carry out (which are based on the assumption that space only has three dimensions) would be inaccurate.
Even though we don’t know the answer for sure, it appears more plausible that we’re missing something in our comprehension of the world when it comes to things that are very small. After instance, if the prediction made by the standard model was accurate, the universe would have expanded at such a rate that it would have been impossible for stars, galaxies, or people to ever have existed.
Nevertheless, a riddle remains a mystery. The plain and basic truth is that scientists have no idea why our theories of the quantum world and the cosmic realm produce such contradictory predictions. Despite decades of research, some of the most brilliant minds in the history of science have not been able to figure out the solution. We will simply have to put off our plans until the day in the distant future when someone solves this cosmic mystery and earns a place among the greats of the physics canon.