The Amazing Physics of N95 Masks (and more)


After all the intense physics I covered, I thought I should mix things up a bit. So, this post is still kinda physics but it’s more relevant to what’s going on around us.

Let’s explore the mind muddling mask physics (it’s not that hard, I just wanted to use the alliteration).

N95 masks or respirators were practically unheard of before March 2020. I don’t imagine you ever came across the term in 2019 (the good ol’ days) unless you have experienced insane pollution or wildfire smoke or been in a construction environment with loads of dust.

An N95 mask

When you hear of N95 masks, you might think of it as I did, a very very very fine strainer with gaps so small that even dust or minute airborne particles can’t get through. In fact, this isn’t how an N95 mask works. The particles they filter are generally much smaller than the gaps in the fibres of the mask (some of the very large particles do get filtered this way but that isn’t their major mechanism).

N95 masks are excellent at filtering the largest and smallest of the small particles. It’s the medium sized small particles that are trickier for it to block. It isn’t in the slightest like a strainer, an N95 is much cleverer, kinda like an Albert Einstein compared to a regular person. 

The principle goal of an N95 mask is to make a particle touch a fibre in the mask. Regardless of the size of an airborne particle, once it touches a fibre, it stays stuck to it. This is mainly due to the size of the particles. At the microscopic scales (in microns/micrometres), everything is sticky because the weak attraction force between molecules known as the van der Waals force is more than enough to get the particles stuck to the fibres quite like a sticky spider web which catches insects as they touch a strand. N95 masks use several clever physical and mechanical tricks to maximise their filtering efficiency.

First, since many spider webs are obviously more efficient than one, so more layers of these sticky particles increases the chances of a particle getting stuck. The particle’s size is a major factor in deciding how likely a particle is to hit or miss a fibre.

Large small particles(>1micron)- These particles basically travel in a straight line due to inertia. So, they are guaranteed to eventually hit one of the fibres and stick.

Small small particles(<0.1microns) – These particles are so light that collisions with air molecules bounce them around in a zig zag pattern known as Brownian motion. This zig zagging pattern too makes it very likely that particles will hit a fibre and get stuck.

Medium small particles (≈ 0.3 microns) – These particles are rather tricky. Instead of travelling in a straight line or moving around in a zig zag pattern, these particles get carried along with the air as it flows around fibres, making it easy to sneak through several layers.

N95 masks have a final trick to catch these particles. They attract particles of all sizes using an electric field. In the presence of this field, even a neutral particle tends to develop an electrical imbalance, attracting them to the source. This is like when you rub a ruler on your hair and the ruler than attracts neutrally charged paper because it is charged with static electricity. The main difference here though is that an N95 mask doesn’t use static electricity, their fibres are permanent magnets but for electricity, electrets. Since you can permanently magnetise a piece of iron by putting it in a really strong magnetic field, you can permanently electretise plastic by keeping it in the presence of a strong enough electric field. This ability allows the fibres to attract particles and so N95 masks filter around 10 times more particles than a regular mask.

To summarise, an N95 mask:

  1. Takes advantage of the inherent stickiness of matter at the molecular scale
  2. Uses many layers of fibres
  3. Uses an electric field that attracts all sizes of particles

These 3 major functions give you a mask that filters almost all large and small particles and a significant chunk of medium sized particles. How much, 95%, thus the name N95. Just like these, you also have N99 and N100 masks which – you guessed it – filter 99% and 100% (99.7% if we’re being exact) of airborne particles. What about the N in the name though? That stands for not resistant to oil.

These are all the types of respirators, masks that offer enhanced protection.

Lastly, who should use N95 masks in this pandemic?

Since the virus propagates through cough droplets which come in a variety of sizes, so the size of the virus is not that relevant.

Size ranges of particles found around us

Normal surgical masks do a pretty good job of keeping these fluids and droplets out. With a shortage of N95 masks in this pandemic, N95 masks should preferably be reserved for healthcare workers or others who frequently come in contact with Covid-19 patients. In fact, since N95 masks are in shortage, people need to reuse them but they are meant to be used only once. There is a lot of ongoing research and some methods being used but some experts suggest that N95 masks should only be used during certain treatments, though this is a debatable factor.

That’s as far as we are going to go about masks. Let me know in the comments if you enjoyed this post and would like to see similar posts in the future. I hope I didn’t bore you’ll.

Thanks for reading and byee!

More Epic Einstein – The Universe Part 4

Hey Hey!

I’m back with some more epic stuff Einstein did and this time we will be exploring General Relativity-kinda like the sequel to special relativity which sorts out all the puzzling parts.

Here we go!

General Relativity-

Special relativity was a truly ground breaking theory but for Einstein, it just wasn’t ground breaking enough. ‘What about acceleration? What about gravity?’, he asked himself. Well, that’s what he spent the next 10 years of his life on. This eventually led to the rise of the General Theory of Relativity in 1915.

General Relativity is an incredibly complex concept and was the work of 10 years in the mind of Albert Einstein so I’m going to go ahead and simplify it as well as I can.

Just so you get an idea of how hard this concept truly is, here is an explanation of it by a renowned physicist Brian Greene when he was told to explain it at the complex level on the Late Show with Stephen Colbert (try reading it fast-it’s insaneee)-

“Space time is a four-dimensional Hausdorff Differential Manifold on which a metric tensor is imposed that solves the Einstein Field Equations, and that metric tensor gives rise to geodesics and objects that are not experiencing any other force move along the geodesics described by that metric.”

The mathematical form explaining general relativity (Don’t worry about it! The simple explanation is coming).

Now let me translate all that gibberish above into simple English. Essentially, it is a theory of gravity. It can help describe the general case of any sort of motion. The major idea it conveys is that rather than being an invisible force of attraction gravity is the warping of the fabric of space-time. The higher the mass of an object, the more it warps the space-time around it and the stronger it’s gravitational pull. Imagine the sun like a bowling bowl on a trampoline as it warps and curves space and it holds the planets in orbit.

The Sun’s gravity as it warps the fabric of space-time and holds the Earth in orbit.

Now as famous physicist Brian Greene said, imagine kids jumping on this trampoline. These are gravitational waves, waves that travel at the speed of light, ripples in the very fabric of space-time that happen when violent processes like black holes colliding occur. What’s even more insane is that Einstein predicted these with math in 1916 and a 100 years later in 2016, we found evidence of these waves.

Gravitational Waves

Just like moving at a significant chunk of the speed of light, makes time pass slower, so does being close to a gravitational mass. This is called gravitational time dilation. However, unlike objects travelling at a significant chunk of the speed of light, objects close to gravitational masses do not experience length contraction. To better understand the concepts of time dilation and length contraction, check out my previous post.

Gravitational Time Dilation-

The warping and curving of space-time by gravitational bodies causes objects closer to gravitational masses to experience a slowing down of time. Time runs slower wherever gravity is stronger so these effects are especially prominent near black holes. Just a few hours on a planet near a black hole might be a few years on Earth.

Since the speed of light in a vacuum is constant, the distorted space-time that is warped under gravitational influence increases the distance a particle of light travels, effectively slowing time down.


  1. The person on the planet near the black hole does not experience the slowing done of time. Everything on the planet from clocks to computers to his brain signals and other bodily functions will seem to continue at a normal pace. Essentially, time will seem to pass at a normal pace for the person near the black hole.
  2. The person on Earth seeing the moving observer will see that he has slowed down. In comparison to him, or relative to him, a clock on the planet close to the black hole will move slower, the astronaut on that planet will seem to talk slowly and will even age at a slower rate.

But all of this would be wrong if there isn’t really a fabric of space-time to warp. How do we even know there is one? There are several experiments that prove this theory.

One of these is gravitational lensing. Light bends around massive objects like black holes and acts as a lens for what lies beyond. This is a method that is routinely used to study stars or even galaxies that lay behind such massive objects.

Gravitational Lensing

Finally, how does relativity matter and what are its real life applications? From nuclear power plants to GPS and even magnets, relativity plays a part in a lot more than we realize. Check this site out to know a little bit more about relativity in the real world.

That’s it for this one guys! If you are free (which you probably are) and a sci-fi fan, go watch interstellar, it’s an amaaaaazing movie.

Stay safe, stay home! Byeee!

Epic Einstein – The Universe Part 3

Hey there!

Hope all of you’ll are doing well. So, in my introductory post, I explored the idea of relativity. In this post, I will expand upon those concepts and hopefully give everyone a better understanding of some of Einstein’s greatest work.

Let’s jump right into it!

Most photos of Einstein portray him as an old man but he was just 26 when he came up with the theory of special relativity.

Imagine you are a future astronaut and humans have figured out a way to make you travel at a significant fraction of the speed of time, let’s say 99.99%. You go on a space voyage at the age of 20 and when you return, your children will have children who will have children who will have children and so on (you get the point) or a zombie apocalypse might have ended the world (that took a dark turn).

You’re probably confused and understandably so. Well, we have Albert Einstein and his Theory of Relativity to thank for that. He proved that space and even time is relative not absolute.

So what exactly is the Theory of Relativity?

The Theory of Relativity is an overarching name that encompasses Einstein’ theories of special and general relativity.

Let’s start of by looking at how time is relative and then we will explore special relativity.

We always assumed time was absolute and that time passed at the same pace for everyone. Then, Einstein came along, “Nononono,” he said, “Time is relative.”

 I don’t mean different time zones because irrespective of your time zone, time is passing at a constant speed. When I say time is relative, I mean there are factors that affect how fast or slow time passes. For example, when 1 hour might pass on Earth, 2 hours might pass in another planet. This is called Time Dilation. The two major factors impacting how fast or slow time passes are:

  1. Gravity-General Relativity (next post)-The stronger the pull of gravity you experience; the slower time passes for you. So, if I’m in a planet close to a black hole and you are on a planet at a distance from the black hole, time will pass a lot slower for me.
  2. Velocity-Special Relativity- The faster an object moves through space, the slower it moves through time compared to an unmoving observer.

Special Relativity-

The year is 1905 and Einstein has just discovered the ground breaking theory of special relativity. Much of this theory was built around two postulates (fancy word for assumptions).

  1. The laws of physics remain the same in all inertial reference frames (if a body is at rest or moving with constant velocity).
  2. The speed of light in a vacuum is the same for all observers, nearly 300,000,000 metres per second.

These two postulates form the base of special relativity that explains the linkage between space and time for observers in these inertial reference frames. It is especially vital in explaining the behaviour of objects moving very very fast, a significant chunk of the speed of light.

Let’s now explore the nature of time and understand time dilation as Einstein explained it in special relativity. It’s better to not imagine time as a stream from past to present and remember it is relative not absolute.

Don’t worry about the numbers.

Stationary Observer

Take a look at the picture above. The observer on Earth is stationary. He has constructed a simple device that shoots a ray of light up to a mirror and it reflects back down to a detector. Since the speed of light must remain constant, it takes the same amount of time for the light to reach the mirror and to return.

Moving Observer

The observer on the rocket is moving from left to right at half the speed of light (don’t worry this is hypothetical). He too has a device identical to the first observer. However, since he is moving, the light must travel a longer distance as can be witnessed in the above photo.

Minor Math Alert!

Since Speed=Distance/Time and the speed of light must remain constant while the distance for it to travel has increased, the only possibility is that time passes slower for the observer on the rocket.

In real life, this is a negligible effect. If a car zooms past you, time passes slower for the observer in the car, in comparison to you but this is soooo little that it can be ignored.


  1. The moving observer does not experience the slowing done of time. Everything on the rocket from clocks to computers to his brain signals and other bodily functions will seem to continue at a normal pace. Essentially, time will seem to pass at a normal pace for them.
  2. The stationary observer seeing the moving observer will see that he has slowed down. In comparison to him, or relative to him, the clock on the rocket will move slower, the astronaut will seem to talk slowly and will even age at a slower rate.

The speed of light though is insanely fast, and time dilation isn’t enough to account for the speed to remain constant for both of our observers. So, something else happens,

Length Contraction: Yup, it just gets weirder. Space/length too is relative.

When you travel at a speed close to that of light, length too becomes less as observed by the stationary observer. This means that light has to travel a shorter distance. ANY moving object’s length will be measured to be shorter than its proper length but just like time dilation, this is negligible in real life.

The effects of time dilation and length contraction to maintain the speed of light-less time has passed for moving observer compared to stationary one and distance appears to be less.

Time dilation and length contraction work together to ensure that the speed of light remains constant and won’t change irrespective of other factors.

What about E=MC^2?

We all have probably heard of this, what does it really mean though?

This was kinda like an afterthought to special relativity. It explains that energy and mass are interchangeable. It’s like saying energy and mass are forms of the same thing like incarnations of the same God. It’s hard to imagine a beam of light being the same as an apple but that’s nature for you. Under the correct circumstances, mass can turn into energy and vice versa. This also explains why we can’t travel faster than light. As an object gets very close to the speed of light, it’s mass shoots up and if an object reaches the speed of light, it has infinite energy and thus it also has infinite mass. So, to reach the speed of light, you would require infinite energy which is impossible.

With that, we come to an end to our simplified trip through what was years in the complex mind of Albert Einstein. Kudos if you got till here. As a bonus, go check out the twin paradox. It’s an epic intuitive video that will help deepen your understanding of special relativity.

Hope y’all enjoyed that post. Feel free to drop doubts in the comments.

Stay safe, stay home and keep learning awesome physics.

Queer Quantum Mechanics-The Universe Part 2

Hello Hello!

As I explored in my introductory post, the world of quantum mechanics or the world of the very very small is an absolutely mind-boggling and crazy place. There are a variety of particles, categorised under bosons and fermions, based upon how much they spin. There is also the famous thought experiment of Schrodinger’s Cat. If you put a cat in a box with a bomb that has a 50% chance of killing it, the cat is equal parts alive and dead, the instant before you open the box. That’s the level of crazy quantum mechanics reaches. On the math side, you need to solve differential equations and know some calculus too. Obviously, this may seem beyond the understanding of a lay person but not all of quantum mechanics is beyond comprehension. This post will put all the crazy stuff aside and attempt to explain quantum mechanics simply for everyone to enjoy so don’t let the topic freak you out. I promise its not all that hard.

To Quantum Mechanics then!

So, I am going to introduce the basics of quantum mechanics in 3 pieces.

  1. Quantisation-

This piece is in the name itself. The idea of quantisation. It states that certain properties at the subatomic level such as energy) come in discrete (separate/distinct) packets called quanta. For example, an electron in an atom can’t just have some random energy level. Well, that’s because there are energy levels in the atom so you can say the energy in an atom is quantised. You can be on level 1 or level 2 but you can’t be on level 1.2. Matter too is quantised because you can’t have half an electron.

What about force, can we quantise that?

Apart from gravity all the forces are quantised. The Quantum Field Theory explains the quantisation of the other 3 forces (electromagnetic, strong nuclear and weak nuclear).

The energy in an atom is quantised, restricting electrons to certain energy levels.

2.Probability and Uncertainty-

In classical physics, we know that something is in a certain place at a certain time. In quantum mechanics, everything is uncertain and based on probability. In fact, this concept of uncertainty is so vital that there is a principle behind it, the Heisenberg Uncertainty Principle. The principle states that we can’t precisely determine both, the momentum and position of a particle at a given point.

Let me simplify. To see an object, we need light, an electromagnetic wave. This wave hits the object and gets reflected to our eyes. Our brain then processes the wave to create an image. So seeing an object is interacting with it; seeing is like touching. Why should this be a problem? It isn’t with most things but particles are very, very small. The standard waves that allow us to see simply passes over these particles. This problem can be solved by making the wavelength much much smaller which in turn increases the energy. When a particle is touched with a wave with such high energy, it gets altered. So in attempt to measure position or momentum, we interact with a particle and thus change it, making it impossible to precisely calculate both, momentum and position. This isn’t a limit to our capabilities but a fundamental property of the universe.

Everything I just explained in an equation. Research a little to understand it better.

3.Wave Particle Duality-

Does an electron exhibit characteristics of a particle? Yes

Does an electron exhibit characteristics of a wave? Yes

Confused?? That’s quantum mechanics for you. Don’t worry though, I’ll explain.

We always imagined electrons as particles and light as waves right? Electron wave and light particle just sound wrong. But what if I told you that matter and light can be described as particles and waves, that we are literally made of vibes (just for the pun- not to be taken literally ). That would be wave-particle duality. As berserk as that may sound, it is proven and actually explains a lot about our universe. However, this peculiar characteristic is described by a wave-function, the mathematical meeting point between wave and particle. Without these ‘particles’ of light (photons) or ‘waves’ of matter, much of the universe wouldn’t be understood like the photoelectric effect. In fact, these electron waves are integral in the probability calculations of an electron’s position.

The Double Slit Experiment was instrumental in confirming this theory. Imagine firing paintballs through two cracks in a wall onto another wall. You would expect two lines to form. However, if you do this with electrons, you get a striped pattern, characteristic of waves.

The pattern (left) is characteristic of waves. The electron waves go through each slit at the same time and then the waves from each slit overlap. Where the waves add together, there is a higher probability of the electron appearing with the center having the highest probability (right).

I know I promised to keep the math out of this but there is one vital number that much of quantum mechanics revolves around, Planck’s Constant (you probably know about this if you’re a stranger things fan). I’m not going to delve into the maths and significance but you can check this link out for more information.

Random Trivia: The smallest particles in the universe are called quarks. They are found in protons and neutrons.

Just some of real world applications of quantum mechanics

That’s about it for now! I hope you enjoyed (and understood) that! Feel free to ask questions or give me constructive criticism in the comments.


The Universe-Part 1-A Breakdown

Hi everyone!

So, this is my VERY FIRST proper post here and I have challenged myself as I am taking on some of the hardest topics in physics and trying to simplify them so everyone can enjoy learning physics.

Keep in mind that I have broken down the basics here and I intend to do a series delving a little further into these categories.

Let’s do this then!

Before we dive into all these mind-boggling concepts, I’m just going to put the definition of space-time out there.

Space-time: The 3 spatial (space) dimensions and 1 temporal (time) dimensions are fused into a 4-dimensional model. It allows us to better visualise the relativistic universe we live in where different observers perceive space and time differently. So space and time can be viewed as one entity called the space time continuum.

The space-time continuum
  1. Quantum Mechanics
The minuscule quantum universe

 The quantum universe is a bizarre, wacky place. It consists of the extremely small stuff, we are talking atomic, sub atomic, sub sub atomic and more, levels at which conventional physics breaks down and nothing works like it should. Quantum Mechanics is the branch of physics that deals with this weird, random behaviour that classical physics can’t explain and sets a whole set of rules to explain all of this. Just to give you a sneak peek into the crazy of the quantum universe, it dictates that an electron can act as both, a wave and a particle! This was enough to blow my mind and this barely scratches the surface of the queer world of quantum mechanics.

2) Relativity

Einstein came up with the special theory of relativity in 1905 and general relativity, years later in 1915.  

Special Relativity- Special relativity explains the linkage of space and time for objects in inertial reference frames (a body with zero net force-at rest, or moving at a constant speed). It explains the behaviour of objects moving very very fast, a significant fraction of the speed of light. It also includes the ever famous equation: E=MC^2.

What if an object accelerates or slows down or what about the effect of gravity? That’s where general relativity comes in.

General Relativity- Essentially, this is a theory of gravity. It can describe the general case of any sort of motion. The major idea it conveys is that rather than being an invisible force of attraction, gravity is the warping of the fabric of space-time. The higher the mass of an object, the more it warps the space-time around it and the stronger it’s gravitational pull. Imagine the sun like a bowling bowl on a trampoline as it warps and curves space and it holds the planets in orbit.

The Sun’s gravity as it warps the fabric of space-time and holds the Earth in orbit.

3) Theory of Everything

The workings of our universe are governed by two sets of rules right now which we just covered.

  1. You have quantum mechanics, which are the rules of REALLY small things. Rules that can very well explain stuff like the decaying of a uranium atom.
  2. There is general relativity, which consists of the rules for the REALLY big things like us, or stars or planets.

Here’s the thing though, when you use the rules of general relativity in the quantum universe or should I say the world of the REALLY small stuff, you get nonsensical, crazy answers. Likewise, quantum mechanics doesn’t account for gravitational effects which is what general relativity is really about.

So for the moment, quantum mechanics is used to deal with the small stuff and general relativity is used to deal with the big stuff. Kind of like how you might use one key for work and one at home. No big deal, right?

       Here’s the catch. We don’t live in two worlds, we live in a single reality, one universe which consists of big and small things so shouldn’t we also have just one set of rules to explain everything? Back to my lock and key analogy, this is kind of like a master key. If we understood how locks work, we could carry around a key to unlock all locks so if we devise one theory for how the universe works, we have with us a master key to unlock and reveal the mysteries of the universe. This master key is what a Theory of Everything is.

The Theory of Everything is one of the major unsolved problems in physics that escaped and frustrated Einstein and generations of scientists after him. While we have potential candidates like the String Theory or M Theory, none of them can be proven or authenticated. The goal of the theory of everything is simply to unify all four fundamental forces: electromagnetism, strong and weak nuclear forces and gravity, also unifying quantum mechanics and general relativity.

TL; DR- Essentially, we have two sets of rules that govern the workings of our universe and the theory of everything is an attempt to create a single set of rules, a hypothetical framework that can describe and link all known physical phenomena in our universe.

Mind Blown??

I know this is confusing and takes a while to wrap your head around so go ahead and read it all over again if you must and ask me any questions in the comments. I’ll try my best to answer.

That’s about it then! Thanks for reading and until next time! Stay safe, stay home and stay happy😃!