Why constants exist

To make the stories rigorous, we would have to have an alternate universe in which what differs is some dimensionless constant such as the fine structure constant. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Learn more. Ask Question. Asked 7 years ago. Active 5 years, 3 months ago. Viewed 5k times. Improve this question. Community Bot 1. I think this is the only one which can be maybe refered as duplicate.

Add a comment. Active Oldest Votes. Alice : That is not a very meaningful question. Bob : What do you mean? Alice : try it. Improve this answer. Johannes Johannes Please write a cute allegory explaining that. For example, why does the fine structure constant has the value it does? And then you use that same ruler to compare it to something else. Note how it does not matter at all, how you marked the ruler. As long as you use the same ruler or at least markings.

Units are just rulers. By comparing and reading off the number, you are reading off the ratio of the thing you are measuring to one ruler marking. That is not at all what the question is asking. If I ask "why are most humans roughly five to six feet tall? That's obviously missing the point. Why do these dimensionless ratios have the value they do? I think the questions are meaningful; changing the units will change the constant's value, but that doesn't mean that value is meaningless.

Would you tell them that the question is meaningless because it depends on the units? They define the Planck units. But what about lots of other parameters? For example, the radius of the Earth has a fixed value in terms of Planck lengths and this value should be predicted at least its probability distribution.

And there are lots of much more fundamental parameters: properties of elementary particles, etc. For example, in Einstein's theories of relativity, mass and energy are equivalent, the energy E being directly proportional to the mass m , with the constant of proportionality being the velocity of light squared c 2 -- i.

In this equation, E and m are variables and c is invariant, a constant of the equation. Here, Planck's constant h is the constant of proportionality. The elementary charge e and the electron mass are examples of constants that characterize the basic, or elementary, particles that constitute matter, such as the electron, alpha particle, proton, neutron, muon, and pion. Additionally, they are examples of constants that are used as standard units of measurement.

The charge and mass of atomic and elementary particles may be expressed in terms of the elementary charge e and the electron mass m e ; the charge of an alpha particle, the nucleus of the helium atom, is given as 2 e , whereas the mass of the muon is given as The fine-structure constant alpha is an example of a fundamental constant that can be expressed as a combination of other constants. Because this particular combination of constants always appears in theoretical equations in exactly the same way, however, the fine-structure constant is really a fundamental constant in its own right.

For example, the fine-structure constant is the fundamental constant of quantum electrodynamics, the quantum theory of the interaction mutual influence among electrons, muons, and photons. As such it is a measure of the strength of these interactions. It sets the scale magnitude of the various allowed electron energy states or levels in atoms such as hydrogen. The accuracy with which many of the fundamental constants can be currently measured is a few parts in a million.

By accuracy is meant the relative size of the uncertainty that must be assigned to the numerical value of any quantity to indicate how far from the true value it may be because of limitations in experiment or theory. This uncertainty is a quantitative estimate of the extent of the doubts associated with the value. The most commonly used uncertainty, the standard deviation, symbolized by the Greek letter sigma, is such that there is about a 68 percent chance that the true value lies within plus or minus sigma.

If you have enough universes, then many of them will have the right balance to allow life, no matter how unlikely it is. Now everyone capable of asking the question will find themselves asking it in a universe perfectly suited for life, despite the fact that the overwhelming majority of universes are completely inhospitable.

The idea that there are effectively or actually an infinite number of universes is not new to physics. All quantum mechanical systems which is everything, really exist in every possible state simultaneously. It might be completely reasonable for new universes to have different physical constants. But how about this: When you create a batch of particles using accelerators mostly the stuff that flies out is in the highest entropy it can manage.

The exact results of particle creation are impossible to predict. What if the creation of the universe followed the same rule? That a universe with its constants tuned for very high entropy is more likely to be created.

Looking around at the universe today, it would seem to be set up to maximize its own entropy. Chemicals of amazing complexity are possible, there are almost a hundred natural elements which requires crazy balance , there are dozens of different types of exotic particles that blink in and out everywhere all the time.

Very unpredictable, very high entropy. By contrast, if you kept everything the same, but changed the mass of the proton from 1. No more chemicals or even elements of any kind. Very predictable, very low entropy. You take for granted that anthropic selection is the only form of the the principle that exists and that this has somehow been proven even though that is a false assumption. This is also the most natural conclusion that one would arrive at by projecting the expansion of the universe backwards to the point that inflationary theory becomes necessary to fill in the unexplained volume.

The last question you answered was asking about the fine-tuning of physical constants. In short: why would one believe that physical constants could in principle be different from what they actually are?

When all the physical constants line up it seems too good to be true. The question assumes facts not in evidence. If you were able to put your imaginary spaceship down at some random point in time and space, you would find that the universe is quite hostile to life. As far as we now know, there is only one planet in this incredibly vast universe that harbors life, and there have been tremendous extinction events in its history, where significant portions of the biosphere have been ravaged.

We may be entering yet another one right now. All life that may have existed then was completely destroyed, and had to start over from scratch. The universe is absolutely hostile to life in general. In my opinion, as a layman, I would first decide if I should answer that question or not.

Since I believe in a God who could have possibly set these constants, it will be entirely hard for me to even start to concentrate on that question. God does not speak to us directly. This question about physical constants will take us to a completely different world.

Dominic, what god do you believe in? God does still speak to us also, you just need to learn to listen the right way. Secondly, I am an uneducated man, but God seems to be the easiest answer in this case.

Just a piece of my brain for you. But nothing in it is really expanding. Everything is curved. But not only that. Everything in it runs in a circle. Its not expanding, its a giant sphere. Energy cannot be created or destroyed. Its not infinite, its perpetual. We invented the right angle.

And corners. I hate school, math, physics, all that shit they made us learn. I hate having to do all of that. I like to look at the broadness of everything and use bigger puzzle pieces. But I remember parabolas and whatever, in math, its always getting closer to zero but will never reach it.

Life, death. I feel the write-up and responses to this question beg another deep and debatable? Us, humans as we understand ourselves, accept certain temperature, pressure, gravity ranges and require certain nutrients, and water. Light and sound are helpful too; extreme sensory deprivation experiments leave the subject raving mad in a short time.