And there are no infinite particle-antiparticle pairs in a vacuum


We often hear the word ‘virtual particle’ in physics and pop-sci explanations of quantum field theory. But, in reality, there are no such things as virtual particles. Today we will explore why (and how) virtual particles are needed, and also why they don’t exist.


Our story begins begins with QFT, i.e. Quantum Field Theory.

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The Higgs field. Source: Wikipedia

The above picture shows the graph of the Higgs field. Think about it like this: at very point in space and time, we assign a random property. This could be a number, a vector, a tensor, anything you want. Then we try to figure out how that property behaves as time passes and other things interact with it. …

And not destroy physics while you are at it?


Light has a peculiar property. It always travels at the same speed, no matter what.

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Albert Einstein, one of the greatest physicists ever. Source:

In 1905, Albert Einstein, while discovering the Theory of Relativity, showed that light travelled at only a constant speed. The speed of light is around 300,000 kilometers per second.

Now, Einstein did not prove this or anything, he just postulated it (which means he took it as an reasonably made assumption). Using this postulate, he discovered the theory of relativity: a milestone in physics.

The theory of relativity (which we won’t talk about here much) has been experimentally proven several times. Experiments including high speed muons, light itself, and high energy quarks have shown the theory to be true. …

And how is it related to falling elevators?

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Photo by NASA on Unsplash

We all know that astronauts who visit space do not feel gravity. How else do you get all the neat spacewalks and the floating globules of water? But, the reason for why this happens is actually a little-known fact.

The Common Explanation

We are told that astronauts float in space because there is no gravity at such high altitudes. This also makes sense.

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Photo by NASA on Unsplash

The International Space Station is approximately 408 kilometers above the atmosphere. We all know that gravity decreases with height. …

And why the whole universe does not travel at light speed.

Objects are heavy. This may be one of the oldest facts that humans have ever known. A apple, and cartwheel, and big bag of chocolate muffins, they are heavy. But what does ‘heavy’ mean? Let’s look at what physics has to say.


The earliest ‘definition’ of mass can be easily attributed to Isaac Newton.

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Isaac Newton has been hailed as the ‘father of physics’ Souce:

According to Newton, things are heavy because of an internal property all objects possess. He called it ‘inertia’. Inertia is a tendency for objects to not move.

To move an object you have to put an force on it. But, the object still resists. If you try and push a beachball it seems to move quite easily, but actually it does resist the push a bit. That is the beachball’s inertia. An ant on the other hand can conform for you that the beachball is hard to move. The puny force that the ant applies cannot overcome the beachball’s resistance. For the ant, the experience is somewhat similar to you pushing on a three story building. …

How I created a fictional world

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Source: Unsplash

Worldbuilding — the art of creating new, fictional worlds, is an amazing skill. It requires an active imagination as well as a well curated vision to guide you and remind you what you want to actually achieve.

Now, I am an amateur when it comes to worldbuilding. I write a lot of stories, but up till now they have been individual ones or short stories. Then, I suddenly had an amazing idea to go create a fictional world. Here is what I did, how I fared and what I learnt in the making of my own fictional world.

Now, by no means I am an expert in this aspect of writing. So, I don’t know if my set of experiences can be considered as guidelines or steps or tips to create fictional worlds. But I guess it’s still a great foreshadowing to what you are going to deal with if you ever get interested with creating your own imaginative lands or even better — universes. …

Copenhagen, Parallel Worlds and Infinite trajectories: Time to dive into the weird.

Every physicist would agree that the greatest paradigm shift of the last century was the quantum. Quantum mechanics has changed the face of science. It can explain everything. Electricity? Yes. How birds fly in one direction? Yes. Gravity? No. But, today we won’t get to that. Instead we will talk about another conflict in the field, the conflict of interpreting quantum mechanics.

Some background:

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The Solvay Conference. This photo contains some of the pioneers of quantum mechanics. Source: Wikipedia

Quantum mechanics began when Max Planck discovered that light actually consisted of particles with some fixed energy. …

Microscopic strings, looped space, and eight dimensional spheres

Physics can be easily considered the most fundamental of the sciences: it can describe almost any phenomena Nature gives us. Gravity. Yes. Why does my coffee cool? Yes. Do atoms exist? Yes.

But internally, within the vast field there has been one lingering problem: two of the best theories physics has to offer are incompatible with each other. We have been trying to fix it; since the last few decades. But, there is only so far we can get.

That does not mean zero progress. In fact, some new theories have been proposed for fixing this huge problem. Here, we will look at some of them. …

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Photo by Greg Rakozy on Unsplash. A brief explanatiion of the universe.

Cosmology has changed our perception on how the universe as a whole started and grows. But, how would you actually do cosmology?

Einstein’s Gravity:

‘Is gravity a force?’ The answer, surprisingly, turns out to be ‘NO’. Our view on gravity was fundamentally changed in 1915, when a bold new theory dared oppose the greatest physicist: Newton. General Relativity describes gravity as an intrinsic property of space and time itself. Here is how it works:

Imagine an object, like a planet. The standard way of introducing General Relativity, is by a rubber-sheet analogy, like this:

Rubber-sheet analogy of General Relativity. Credit:
Rubber-sheet analogy of General Relativity. Credit:
Credit: Rubber sheet analogy

But this is totally misleading. Instead, it’s better to view it this way

‘In the presence of matter and energy, the surrounding space and time is not Euclidean i.e. …


Pravit Shetty

An ever enthusiastic reader, physics nerd, math geek, and amateur writer.

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