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-------------------- 2493 - MASS - what is it really?
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- We say a particle as mass. What do we mean? Sometimes the word “mass” is used interchangeably with the word “weight.” That’s not entirely wrong. The mass of an object is measured by its resistance to a force.
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- When you pick something up to test its weight, it is resisting the Earth’s gravity, so an everyday object’s weight on Earth is indeed one measurement of its mass.
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- But there’s more to mass than just a resistance to gravity, especially on the scale of the smallest pieces of matter. The definition of mass gets a little more complicated.
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- Most fundamental matter particles, such as electrons, muons and quarks, get their mass from their resistance to a field that permeates the universe called the Higgs field. The more the Higgs field pulls on a particle, the more mass it has.
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- When it comes to composite particles like protons and neutrons, which are made up of quarks, most of their mass comes from the pull of the strong force that holds the quarks together. Remember mass and energy are two different forms of the same thing.
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- Photons and gluons, two force-carrying particles, are fundamental, so they don’t host the internal tug-of-war of a composite particle. They are also unaffected by the Higgs field. Indeed, they seem to be without mass.
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- Massless particles are purely energy. These quanta of energy don’t have edges, and they don't have surfaces. These massless particles always travel at the speed of light.
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- A better way to think of ‘particles’ is as ripples on a quantum field. A quantum field has vibration modes like the harmonics on a guitar string. Pluck it with the right frequency and you get a particle.
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- The two particles physicists know to be at least approximately massless are photons and gluons. Both force-carrying particles, also known as gauge bosons. Photons are associated with the electromagnetic force, and gluons are associated with the strong force.
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- The graviton, a gauge boson associated with gravity, is also expected be massless, but its existence hasn’t been confirmed yet.
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- These massless particles have some unique properties. They are completely stable, so unlike some particles, they do not lose their energy decaying into pairs of less massive particles.
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- Because all their energy is kinetic energy, they “always” travel at the speed of light. And thanks to special relativity, things traveling at the speed of light don't actually age.
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- Gravity affects anything with energy, even a particle that has no mass at all. That’s why the gravitational attraction of objects like galaxies and clumps of dark matter curves the path of light passing by them in space.
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- Photons and gluons, two force-carrying particles, are fundamental, so they don’t host the internal tug-of-war of a composite particle. They are also unaffected by the Higgs field. They seem to be without mass.
-
- Massless particles are purely energy. These quanta of energy don’t have edges, and they don't have surfaces
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- A better way to think of particles is as ripples on a quantum field. A quantum field has vibration modes like the harmonics on a guitar string. Pluck it with the right frequency and you get a particle.
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- These massless particles have some unique properties. They are completely stable, so unlike some particles, they do not lose their energy decaying into pairs of less massive particles.
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- Because all their energy is kinetic, they always travel at the speed of light. And thanks to special relativity, things traveling at the speed of light don't actually age. So a photon is actually not aging relative to us. It’s timeless, in that sense.
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- Gravity affects anything with energy, even a particle that has no mass at all. That’s why the gravitational attraction of objects like galaxies and clumps of dark matter curves the path of light passing by them in space.
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- It never entered my mind that my 180 pounds of mass was so complicated? Stay tuned, there is a lot more to learn. I think Thanksgiving dinner is going to add to my mass. But, what you learn does not make you any heavier.
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- November 24, 2019 2493
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--------------------- Sunday, November 24, 2019 --------------------
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