Date: October 3, 2022.
Earlier this week, I measured my weight, and the scale read 41.7N (skinny!). Then I wondered, what is weight? Well, it is the force acting upon me due to gravity, which means on different planets I will have different weights depending upon their respective gravitational acceleration (weight = mass x gravitational acceleration).
But then, what is mass?
Newtonian/ Classical mechanics says, there are two types of mass- inertial mass; the mass that resists motion (the reason why it’s difficult to push a car), and gravitational mass; an object with more mass is attracted by gravity more strongly to other masses (F= G x m1 * m2 / r²). When you drop a hammer and a feather together from a distance, you’d expect the hammer to drop first, right? But No! Galileo stated centuries ago that objects with different inertial or gravitational mass, fall at identical rates because they experience identical inertial acceleration.
It turns out that Newtonian mechanics isn’t fundamentally correct.
However, Newton’s laws are accurate for 99% of the things in 99% of the universe (DAMN!!!). But what is that 1% of the 1%? Let me introduce you to the physics of relativity and quantum mechanics. From the experiment of hammer and feather, Einstein took this idea and said, inertial mass and gravitational mass were identical, which denotes that there is only one kind of mass- relativistic mass (E = mc², m= relativistic mass).
From Einstein’s equation, it can be said that when you’re measuring the mass of an object, you’re actually measuring its complete energy content. Rest mass is the mass of an object which is at rest, relative to us, and it is the main determinant of mass. But this changes in cases such as if the object has less rest mass or when the object is in motion. However, light doesn’t have a rest mass, because it is traveling at the same speed everywhere.
Now that we know about relativity, let’s take a look at quantum mechanics. Like the building block of life is the cell, the building block of matter is elementary particles. Atoms are not the smallest particles in the universe. We have something called the standard model, which is a table that comprises all known elementary particles in this universe.
Each atom has a nucleus which consists of protons and neutrons and orbiting the nucleus are the electrons. The electron was the first standard model particle discovered. Protons and neutrons are made of three quarks each (proton= two “up” and one “down” quark; neutron= two “down” and one “up” quark). The remaining four quarks can only be seen in particle accelerators.
Muon and Tau particles are similar to electrons; muons are 200x and tau particles are 3477x heavier than electrons. The remaining three leptons are neutrinos corresponding to the electrons, muons, and tau particles which are created from the decay of these particles. Neutrinos are neutral and pass through a lot of matter without hitting the atomic nucleus (Fun fact: there are billions of them passing through us right now).
Gauge bosons are particles that carry force. Fundamentally, there are four forces- gravity, electromagnetism, and strong, and weak nuclear forces. Gluons bind the quarks in the protons and neutrons and carry strong nuclear forces. Photons carry electromagnetic force. The Z and W bosons are the carriers of weak nuclear forces.
Then where does gravity fit in this model? That’s yet to be answered. . .
With the standard model, scientists were able to describe the subatomic particles and how they interacted with each other but they couldn’t describe how they gained mass. Later, in 1964, Peter Higgs, and Francois Englert proposed the Higgs theory. The Higgs field is a field of energy that exists throughout all of space and it is composed of the elementary particle- the Higgs boson. All subatomic particles pass through the Higgs field and interact with the Higgs boson, thereby gaining mass. Simply put, the interactions result in mass acquisition. The photons pass through the field without any interactions and are, therefore, massless.
The Large Hadron Collider (LHC); one of the most complex machines built by humanity, is a large ring-shaped machine, inside which beams of charged particles rotating in opposite directions are hit against each other constantly to make them fly faster and faster until they collide leaving tracks of subatomic particles. On very rare occasions, the Higgs boson (one in billion collisions) can be seen and such a golden event did occur on the 4th of July 2012. This event showed us the God particle for the first time and proved the existence of the Higgs field which is present across the whole cosmos.
During the early moments, following the big bang in the universe, all the elementary particles were massless. They were energy streams that traveled at the speed of light. However, as the expansion of the universe was proceeding, the density and temperature decreased below a certain point and that’s when the Higgs field came into action. So we can say that mass isn’t the primary property of a matter, but it gains its value through mere interactions with the Higgs field.
Ironically Higgs field is responsible for only 0.1% of the mass in the universe (WHAT?!!!), the remaining mass comes from dark energy and dark matter. But, if the Higgs field didn’t exist, electrons wouldn’t have mass and therefore atoms wouldn’t exist and so neither would we or anything else in the universe.
0.1% on a cosmic scale, is kind of a big deal!
The detection of The God Particle is just the beginning of a whole world of unknowns linked with the field of science, mathematics, technology, and engineering.
Ah! The sub-atomic world sure is MASSive! Ha ha…
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