Hubble constant, gravitational constant, Planck constant, Boltzmann constant, speed of light, π, dielectric constant of vacuum, magnetic permeability of vacuum, conductivity, resistivity, Coulomb constant, etc... of the constant family The team is still growing. Anyone who has st

Hubble constant , gravitational constant, Planck constant, Boltzmann constant , speed of light, π, dielectric constant of vacuum, magnetic permeability of vacuum , conductivity , resistivity, Coulomb constant, etc... The team of constant family is still expanding. Anyone who has studied basic science has encountered at least one physical constant, such as the speed of light or the mass of an electron. This is inevitable.

Scientists, especially physicists, must memorize these constants (or at least be very familiar with them) because they make many calculations easy. But it’s amazing when you stop to think about these constants and the properties of some aspect of the universe they describe. These huge numbers aren't just for our computational inconvenience.

We know the values ​​​​of many constants, but where do these values ​​come from? Are these constants created by scientists, or do they exist naturally? What do they mean for physics? Will they change? If so, why do we call them "constants"?

What do these constants mean?

The Hubble constant tells us the expansion of the universe and the speed at which stars are moving away from us, ultimately helping us calculate the age of the universe. Nearly 100 years have passed since Edwin Hubble first calculated it in 1929, and scientists are still debating its actual value. With every leap in technology, and with every new (more sophisticated) telescope, the Hubble constant "changes." Finding the precise value of the Hubble constant remains one of the greatest challenges in modern astronomy.

The gravitational constant, sometimes also called Newton's constant, is the proportional constant used in Newton's law of gravity, represented by G. Whether on Earth, on Mars, or on some distant planet thousands of light-years away, the value of the gravitational constant does not change.

Planck's constant gives the relationship between the frequency of a particle and its total energy. This is a breakthrough discovery in the world of physics, because one of the quantities is a property of the wave (frequency) and the other is a property of the particle ( energy). Therefore, the wave-particle duality of matter was proven, and ultimately paved the way for the development of quantum physics.

We can define individual constants by what they represent (physical quantities), but can we give several constants an overall definition (meaning)? That is, we need to define certain quantities of the universe in the units we specify, such as meters, newtons, light-years, and joules.

For example, the unit of G for the gravitational constant is:

When G is multiplied by the mass of two objects and divided by the square of the distance between them, you get the unit of force, Newton (N). This is exactly what we need because we want to know the gravitational force between two objects:

Therefore, the numerical value of the constant will depend on the unit system we use.

So does this mean the constants are constructed by humans? Absolutely not! This definition is about what a constant does, not what it is. In addition, it cannot define all constants, because there are also dimensionless constants, such as the famous pi π.

Pi is an irrational number , and it is a transcendental number. It appears in many phenomena in nature. From the DNA double helix structure, to the ripples in the pond when throwing stones, to zebra stripes and leopard spot patterns, to the famous Heisenberg principle, to the structure of earthquake-resistant buildings, to the rise and fall of ocean waves - pi everywhere. It fades away at the center of the universe and appears in the most complex mathematics.

It is a constant with no unit and we don't know why this is the case.

How are their values ​​determined?

There are some constants whose values ​​are controversial, and errors will always exist, depending on the accuracy and sensitivity of our existing equipment. Constants are not created by scientists. They exist in the universe, we only measure them through repeated experiments and observations.

has another question that delves deeper into the mystery of the constants. In a paper published in Nature on February 20, 1937, the famous physicist Paul Dirac raised a question that still puzzles physicists today: If we look at the entire Are all constants really constants in the history of the universe? After all, all of our measurements are made on Earth. Does what is constant here also be constant elsewhere?

• Paul Dirac's paper

Then there is evidence that the "ratio of proton mass to electron mass" is constant. Over the years, numerous research groups from many countries have explored the most distant corners of the observable universe simply to determine whether the mass ratio of protons to electrons changes. Each time, the result was the same. The mass ratio remains unchanged.

constants do change, such as the Hubble constant (the initial value measured by Edwin Hubble was more than 7 times the current value of the Hubble constant), but this is due to human error and equipment accuracy.

We cannot explain why these constants are the way they are, how they are determined by nature, and whether they can change over billions of years. We can only measure what is already there.