The one about Energy

In my last blog, we learnt how all matter is made of two basic building blocks — quarks and leptons. We also learnt how these two ingredients combine to make all the elements on periodic table. And we learnt that every single one of these elements is fused inside stars under immense pressure. In this blog, I hope to explain the energy side of things. Remember only 5% of universe is made of matter. That 5% also includes all the energy that we will discuss in this blog. Rest 95% is dark matter and dark energy which we won’t discuss.

What exactly is energy? Per science textbooks, energy is anything that allows us to do work. This work could be moving, heating, breaking, or lighting up an object. But what exactly is it?? What fundamental property allows us to do all those things? Let’s try tackling this by first understanding two facts about energy:

1. Every matter in the universe radiates energy. Some less, some more, but they all do. This is because all fundamental particles vibrate. Higher temperature = higher vibration; lower temperature= lower vibration. In fact, it is impossible to stop this vibration. You would have to cool something down to absolute zero (-273 C) to take away ALL of its energy. But cooling something down to absolute 0 is prohbited by universal law just how going faster than light is prohibitied.
2. All the energy that exists inside these vibrating particles was once inside that infinitely small point in spacetime that existed right before Big Bang. It’s that very energy that has been circulating till today converting from light to heat to movement to electricity to anything and everything. Every single energy example can be traced back to the Big Bang.

There are 3 basic kinds of energy:

1.Potential energy — This is stored energy. For example, rock perched on a ledge has gravitational potential energy, gasoline contains chemical potential energy hidden in the carbon bonds. Mass itself is a form of potential energy (remember from last blog how 99% of mass of an atom is hidden inside the energy required to bind the quarks into protons and neutrons?), as described by Einstein’s famous equation E=mc²

2. Kinetic energy — This is energy of motion. For exmple falling rocks, orbiting planets, moving molecules in air, vibrating fundamental particles all have kinetic energy. The vibrating particles also have thermal energy which is classified as a kind of kinetic energy. Again higher temperature = more vibration and not possible to stop vibration because that would require absolute 0 temp. But it’s important to understand the difference between thermal energy and temperature. This difference allows you to put your hand inside a 400 F oven without burning yourself, while putting your hand in a 100F boiling water would burn you pretty bad. The difference is in density of particles (more in boiling water and less in oven air). This same difference allows us to send the Parker Solar Probe to 1,000,000 F atmosphere of Sun without much problem because there arn’t enough particles in space to transfer this heat.

3. Radiative energy — This is energy carried by light (heat from campfire or sun, electricity). This is everything on the electromagnetic spectrum. Electromagnetic radiation is one of the many ways that energy travels through space. The heat from a burning fire, the light from the sun, the X-rays used by your doctor, as well as the energy used to cook food in a microwave are all forms of electromagnetic radiation. While these forms of energy might seem quite different from one another, they are related in that they all exhibit wavelike properties. Radio, microwave, infrared, visible light from red to blue, ultraviolet, x, and gamma rays are all forms of light. The tiny range of frequency (380–740 nm)that human eyes can detect falls under the visible spectrum of EMR. This starts with Red having the lowest energy and ends with violet having the highest energy. This is why blue flame is hotter than red flame. Our sun shoots out all photons from radio waves to gamma waves. Photons with more energy (uv,x,gamma rays)will vibrate faster creating higher frequency waves. These higher frequency waves are also more likely to knock off electrons causing damage. Luckily our atmosphere protects us from the more damaging high energy waves. Some UV rays make it through which sunscreens protect us from. Some of these highest energy waves called gamma rays are created during supernovas and inside black holes.

The Electromagnetic Spectrum- Radiowaves have long wavelength and low frequency so they have less energy compared to Gamma rays that have short wavelengths and high frequency.

High frequency = high energy ; Low frequency = low energy

How is the energy carried by these waves transferred to other objects? For example it’s these very waves that heat up earth’s surface or evaporate water on a hot day. The waves can be divided into smaller packets of energy called photon.

PHOTON

A photon is the basic unit of light or of the electromagnetic spectrum. It’s a particle of light but also a wave (this is the realm of quantum physics that I will tackle on a different blog). Every photon carries a specific amount of energy which is depended on it’s frequency expressed by this equation:

E=hv where h is the Planck’s constant and v is frequency

So, u can see that higher frequency yields higher energy. If you know the frequency of the radio, red light, or uv light photon then you can calculate just how much energy it’s carrying. These photons then go and hit an electron on an atom. If it had just the right energy, the electron will absorb the photon and gain energy moving to a higher level. Eventually, that electron will lose the same frequency photon and drop back to a lower energy level.

In this diagram, the x-ray photon had enough energy to knock the electron off the atom completely. Now, that atom is a positively charged ion. This is why x-rays are considered ionizing radiation and can be harmful.

What photons get reflected vs absorbed by the atoms on a surface determine what color the surface appears. Because the energy of photon required to knock electrons off is so precise and specific to the atom, each element on periodic table has something called the electromagnetic signature. It’s like a finger print but for elements. So, what this means is that just by collecting light/photons being reflected off surfaces we can tell exactly what the surface is made of. Light really is information. It’s data. Instead of 0s and 1s, it’s frequencies.

Electromagnetic signatures of different elements. The bright lines show frequencies of reflected photons. Hydrogen atom will always reflect photons of specific frequencies and so will neon, iron, and all elements creating a fingerprint of a sort.

Interesting fact: Photons take 8 minutes to reach earth from the surface of sun, but it takes them 100,000 years to go from Sun’s core to surface!!!

There are also two different sources of energy:

Renewable energy — solar, geothermal, wind, biomass, hydroelectric

Nonrenewable energy — fossil fuels (petroleum, coal, natural gas), nuclear

FOSSIL FUELS — Focusing on fossil fuels because this is where 80% of the worlds’ energy comes from

About 350 million years ago, during the Carboniferous period, many plants, algae, and microorganisms died and got buried in clay or other material that kept them from decomposing and releasing all the stored potential energy back to the ecosystem. Over millions of years, as more stuff piled over, the intense pressure turned the stored carbon into coal, oil, and natural gas. By burning those fossil fuels, we are releasing 350 million year old carbon that Earth’s carbon cycle had already accounted for.

Where did those dead plants gain the energy from in the first place? PHOTOSYNTHESIS — process where plants use sun’s energy to convert carbon dioxide and water into an energy storing molecule called glucose releasing oxygen as a byproduct. Burning a log is essentially reverse photosynthesis. Carbon and oxygen combine to made carbon dioxide which is released in atmosphere and the stored energy is released as fire. Similar to burning fossil fuels. As far as we know, photosynthesis is the only way to convert light into food. So, we reallllly need those plants. Plus they also release oxygen.

Energy is stored in the carbon-carbon and carbon-hydrogen bonds of glucose which other living organisms consume for energy.

Now finally to tie it all together let’s look at two examples:

1. I am able to type this blog because I gained kinetic energy from the potential energy stored in the chemical bonds of the apple i just ate(how our body metabolizes food into energy currency called ATP is an amazing story for a future blog). My apple got its energy when the tree it was part off used photosynthesis to create the apple. The suns energy came from the fusion happening inside. The fusion energy comes from the intrinsic properties of atoms created during the Big Bang.
2. My laptop is able to publish this blog on the internet because of the energy from the electrical grid. Electricity is just flow of electrons. Remember photons with specific energy are able to knock electrons off. Attach this to a copper wire and you have electricity. Also you can think of electricity as a universal currency of energy. With electricity, we are capable of converting one energy source to any kind of energy. We take this for granted now, but before electricity, this was not possible. In my laptops case, this electricity is created from fossil fuels. Fire from the fuels heat up water creating steam which turns a turbine connected to a coil of copper wires surrounded by magnet. This creates electricity that’s sent to the power grid. Energy was deposited in fossil fuels from the Sun which got it from the Big Bang.

And that’s all that you need to know about energy. Hope you found this informative and not boring. Until next time :)