Tag: physics

Yes, Light Can Push Physical Objects

By Anupum Pant

Tim is a 71-year-old eccentric who has been collecting interesting toys for 50 years now. Today he has a collection of around 250,000 absurd toys in suitcases, labeled and stacked in a room from the floor to the ceiling. He shows them off in a Youtube channel regularly. I almost never miss any of his toys. Usually most the toys he displays amaze you, but do not blow off your mind. The last one did.

Before this, I had not known that light can push or move a physical object. So, I decided to investigate a bit.

The Extraordinary Toy

In his last video, he showed off a beautiful glass bulb mounted on a wooden stand, that he says has been made by some German company. The bulb has a very good vacuüm (not complete vacuüm, just enough to not create unnecessary drag for the vanes) and encloses a fan-like structure that starts rotating when a bright light is switched on near it. Some people call it the light mill – like the wind mill moves with the wind, this one moves when photons hit it. If give enough time, the mill can accelerate to really good speeds (at thousands of rounds per minute). Watch the video below. [Video]

Theories on how a radiometer really works

The device, a special kind of radiometer, was invented around 140 years back in the year 1873, by Victorian experimenter Sir William Crookes to measure the radiant energy of heat or light. It has four vanes mounted at the edge of four stiff wires to make a fan, each of which has a black side and a silvered side. All of this is enclosed in a bulb which is evacuated enough to not cause drag due to air. In complete vacuüm the vanes move in an opposite direction, but that experiment is really difficult to recreate!

  1. When light is turned on, the fan moves in a way that makes it look as if light is pushing away the black colored side. The theory of photons pushing the black side was accepted initially. But soon a problem was seen with the theory. If light is absorbed at the blackened side and reflected at the silvered side, the fan should be moving in the opposite direction.
  2. Then came in the other explanation which explained that the heated black side due to absorbed radiation rarefied the air near the black side and hence caused the gas to rush in and push that side. The greater the heat, the more this back side would get pushed and it would spin faster. Later even this theory was proved to be wrong. But, Britannica, till date decides to go with this explanation – to some extent this theory goes in the right direction, you will see why…
  3. One more theory claimed that the heat evaporated the impurities on the black side, whose force made it spin.

How the radiometer really works?

The correct explanation was given by a  prominent Anglo-Irish innovator, Osbourne Reynolds. He explained it by mentioning a porous plate, where the air inside the holes would flow from the colder sides to the warmer side (obviously) and make the vanes spin in the opposite direction. He called it “Thermal Transpiration” – makes sense and is easy to understand. But the vanes here are not porous. So…

He said that “Thermal Transpiration” in the vanes takes place at the edge of the vanes and not the faces. Think of edges as small pores, he said.

Due to a temperature gradient formed, the air starts moving along the surface from colder to the warmer side through the edges. The net pressure difference around the vane is created which pushes it in a direction that is away from warmer air and towards the colder air – makes sense for the apparatus.

This is the reason, if it is cooled, it moves in the opposite direction.

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Gravity Defying Chain of Beads

By Anupum Pant

Chain of Beads

Suppose, you have a neat pile of a really long chain of beads in a beaker (Newton’s beads) and you give one end of the beads a tug and let it drop on the floor, what do you think will happen?

Steve Mould, a YouTuber, did the same with a 8000 bead chain. It was 50 meter long chain of beads placed neatly in a container. Then, after he tugged it out and let it drop, the chain mysteriously formed an arc above the beaker and continued to self-siphon away till the end. Just like a water-siphon.

Watch it in video to see what happens. [Video]

What keeps it going?

To figure out what was actually going on here and to understand the exact physics of it, a group of physicists recorded the “gravitational defiance” using a hi-speed camera. Here is a five-minute long video-bliss, brought to you by the Earth Unplugged channel. [video]

As Steve explains, it is like a tug-of war between the outer chain and the inner chain. The inner chain has to keep up with the fast-moving outer chain. As a result, it [the inner chain] goes up fast. It builds up momentum and is unable to stop itself. So, it ends up forming that arc while it is trying to slow down and change direction.

Meet a 12-year-old Scientist – Peyton Robertson

By Anupum Pant

Today we meet a 12-year-old ‘man’ who has been on an invention spree since he was just 8 years old. If I may use a pop-culture reference, this adorable boy is a Sheldon Copper in the making.

Peyton Robertson from Fort Lauderdale, Florida, presently has 3 patents pending:

  1. A case (box) to maintain a resting golf ball’s temperature – Peyton loves golf. And on one cold day, when he observed that his golf balls weren’t bouncing the way they should have been, he, instead of sleeping on the problem, thought of finding a solution.
  2. Retractable training wheels: This one is a pair of retractable training wheels connected to a lever mechanism on the handle of a bicycle – you press the lever and the training wheels rise up. A perfect solution for kids who want to experience the joy of biking while they are learning to ride. He invented this to help his sister when she was learning to ride a bicycle. Today, bike manufacturers are flocking around him to buy his idea.
  3. A sand-less sand bag: When the super-storm Sandy struck 24 US states in October last year, the entire eastern sea-face from Florida to Maine suffered great losses. It caused a damage of around $65 billion. Peyton saw this and figured that the sand bags that were being used for flood defense contributed to a lot of inefficiency. These bags were 40 pounds each; moving them from one place to another was tough. But they had to be heavy to stop the water. Besides that, the bags when stacked left undesirable gaps in between, which caused a leakage. Peyton felt a need to contribute to make people better equipped for floods in the future.

His solution – A sand-less sand bag – is better than the traditional bag in two ways. Firstly, weighing around 4 pounds, it is significantly lighter than the sand bag. It contains a mixture of, a polymer that expands when it comes in contact with water, and salt which makes it heavy when it wets. Secondly, this bag comes with an interlocking fastener which keeps the bag in place when it expands – Removing any gaps which could create a leak during the floods. Moreover these bags can be dried later to be reused.

The witty sandbag made him the youngest ever person to win the Discovery Young Scientist Challenge. The prize – $25,000 and a trip to Costa Rica!

In an interview with TED blog he said:

Failure is progress and a normal part of the process. Whether it’s science or life, you have to start, fail and just keep pushing. In a football game, time runs out, and a golf match ends after the last hole. But when you are working on something and it doesn’t work, you just extend the game – and give your experiment or your prototype another go.

It was a delight to watch the charming boy speak on The Ellen DeGeneres Show. Sadly, that video no longer exists, here’s a replacement with the guy’s own pitch:

Brazil Nut Effect – Saving Lives in Snow

By Anupum Pant

The effect

Have you ever noticed that the larger nuts (Brazil Nuts) in your Muesli boxes or bowls end up on the top? It turns out, scientists have a name for this effect. They call it the Brazil Nut effect or Muesli Effect. Well, actually scientists prefer to call it Granular convection.

If you haven’t heard of Muesli, think of a bowl full of random nuts. Or Indians could think of the Haldiram Navratan Mix – A popular snack mixture that contains several types of fried ingredients in various sizes. Irrespective of the kind of snack or even a mixture of sand you think of, it shouldn’t come as a surprise to you that the smallest of particles always end up at the bottom of a mixture when shaken enough.

If you think there is nothing cool about this effect, you are probably picturing it wrong. Watch this video where, on shaking, big marbles magically come on top of a rice heap.

Research studies

Normally, isn’t it common sense to assume that the largest (presumably the heaviest also) particles should end up at the bottom? Such is the counter-intuitive motion of particles in granular mixtures that it gives scientists a great insight about the real physics that goes inside. So they love to study more about this phenomenon.

This effect is so popular among scientists that some have studied it in martian and lunar gravity simulations. To do this they had to go on a plane that moves in parabolic arcs to simulate a specific reduced gravity conditions – A reduced gravity aircraft.

It saves lives

In the snow, sport persons or people taking part in extreme sports carry an avalanche safety bag with them.  On a free ride down a snowy cliff, sometimes these people get caught in avalanches. Being on top when the avalanche has settled helps the rescue teams find them. The avalanche safety bags are huge when they are inflated. And thanks to the Brazil Nut effect, these big bags attached to the sports person, often end up on the top.

The Reverse Brazil Nut Effect

And sometimes there is a reverse Brazil nut effect. Meaning, if certain conditions are met, the largest nuts can end up at the bottom of a container.

The shape of the nuts, shape of the container and the relative sizes of nuts plays a role in determining if the effect reverses or not. As a simple example, using cone shaped container reverses the effect.

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Sun’s Green Flash

By Anupum Pant

More often while setting than rising, if the conditions are right, a part of the sun (on the top) can appear green. This happens for very short interval lasting for about 2-3 seconds and is considered a rare phenomenon. Since it is green and lasts for a very small interval, it is also called the green flash, emerald flash or green ray. If you have ever captured it or plan to do it in the future, do share your results with me through mail/twitter. [See the animation] [Real GIF]

What does it look like?

Sometimes the sun’s rim can appear green (in optically zoomed images). Otherwise, when the sun is set, for a brief moment, it appears as if a part of sun has separated from the main body and has turned green. It is usually seen as a horizontal line, like in the video below. But, a few lucky ones have captured complete green auras too.

Why does it happen?

The sun gives out a white light, which contains all the colors – Green is one among  them. Normally, our eye isn’t able to resolve the separate colors and sees them as a mixture which is white. When the sun sets, our atmosphere acts like a prism and bends the colors. A few colors get bent more than others. For example, green bends more than red. As a result the two colors get separated enough to be resolved by our eye. But the right amount of bending happens only if the atmospheric conditions are right.

In extremely rare cases, blue or violet flashes have been reported. [image]

For a detailed explanation you can go through this – [Geometric Optics of Green Flashes]

At poles where the sun moves in a different manner, probably the green ray can last much longer. Admiral Richard Byrd has claimed to have seen this green flash for 35 minutes while on an expedition to Antarctica.

 

Is Glass Liquid Or Solid

By Anupum Pant

Glass stories have tormented me for years. A few well informed gentlemen, over the years, have communicated to me anecdotes that have contradicted and shown glass as liquid or solid, without solid proofs that could have helped me believe just one of them. A few days back, like I cleared my doubts about the gas station and cellphone story, I decided to find this out too. So, what is it really? Is glass liquid or solid?

Glass is a liquid?

1. Antique glass panes: A couple of years back I was told (I don’t remember where it came from) that glass windows of very old buildings have glass panes that have been found to be thicker at the bottom. That, according to them, absolutely proves that glass is a liquid that flows very slowly. And apparently explains, how the lower parts of these old panes get thicker – the glass from the upper part of the pane flows down as time passes. I thought it would be something like the world’s slowest experiment; so it could be true.

Till today, I had believed the same. It turns out, I was wrong all along.

Explanation: Firstly, there is no statistical study ever conducted that proves, all antique window panes are thicker at the bottom. Secondly, even if all of them are really thicker at the bottom, the difference in thickness has nothing to do with whether glass is a solid or a liquid. The cause of thicker bottoms is due to the fact that glass manufacturing process that was employed at the time wasn’t able to create perfect glass panes (with uniform thickness). The process made it almost impossible to produce glass panes of constant thickness.

Or, you could simply wait for a few years to see if perfect glass panes stuck on skyscrapers today mysteriously turn thicker in the bottom.

If you think you can NOT take my word for it, I have a quote for you from a distinguished science textbook – Glass Science – below:

Glass is an amorphous solid. A material is amorphous when it has no long-range order, that is, when there is no regularity in the arrangement of its molecular constituents on a scale larger than a few times the size of these groups. A solid is a rigid material; it does not flow when it is subjected to moderate forces. – Doremus, R. H. (1994)

2. Glass is a Super-cooled liquid? : This misunderstood phrase from Gustav Tammann’s book is probably the origin of the myth that glass is a liquid. The quote “glass is a frozen supercooled liquid” has been misquoted hundreds of times with the word “frozen”, forgotten. Today, this misquotation has grown to such great levels that it is actually difficult to go down and extricate the original quote that contained the word “frozen” in it. One word can indeed make a huge difference.

Finally, glasses are only amorphous solids. Where the term amorphous and solid have been separately been explained clearly in the year 1994 by Doremus R. H.
Together, these two words mean the same as definition of two separate words put together. Glass is not a liquid.

If you haven’t read about the ancient Nanotech marvel, Lycurgus cup, you are probably missing something amazing about ancient glass technology.

[Read more]

There Is No Pink

By Anupum Pant

As we’ve seen before in a talk by David Eagleman, that there is nothing like colors really. They are simply electromagnetic waves with varying wavelengths. Colors are perceptions created by our brains that give us an evolutionary advantage to differentiate things easily. Without colors it would have been really difficult for us to spot fruits on trees. Of course that is just one of the millions of examples of how colors help us.

Perception kept aside for a while, we actually do know that there is a spectrum of visible light as we see it – ranges from violet to red. We see this spectrum on rainbows and thin films. Each of these colors on the spectrum is a wave (and particle) that has a particular frequency.
Mysteriously, the universal symbol of love, the color pink, is absent in this spectrum. There is no specific frequency for the color pink. There is no pink. Still we see it. So, what is pink, really? If it isn’t in the spectrum, why do we see it?

Why do we see pink?

Single type cone alone: We detect colors through these things called cones that are present at the back of our eye. There are 3 types of cones – let us call them red, blue and green. So, if an object absorbs all the white (sun) light and sends just the red color [waves] towards your eyes, red cones get activated and your brain tells you, you are seeing the color red. Similarly, green or blue cones get activated when the respective green or blue waves come towards your eye and then you are able to see the colors green or blue.

2 of them together: For other colors, things can get a bit complicated. To see pure yellow, both red and green cones have to get activated. Similarly, when green plus blue cones get activated, you see cyan, and blue plus red cones let you see the color magenta.

But cone aren’t switches that go either one or zero. They are like sliders. For instance, to see the violet color, your blue cones get fully active, while the red cones are activated only to a certain extent. As a result, your brain says, violet! That is 2 types of cones working together.

3 of them together: Now let us see how three of them work together. The color white activates all the 3 type of cones fully. Black activates none. And so on…

Pink does something similar as it uses three types of cones. To see pink, all three types of cones have to work together.  When red cones get fully active and the other two are only partially activated, we see the color pink.

So, even if objects don’t reflect magenta, yellow or pink (or several other RGB combinations like that), our cones can send mixed signals to our brains and the brain in turn creates these colors for us. In reality, they don’t exist.

[Read more]

What is pink really?

Henry Reich of minute physics, in his video explains this by referring to pink as white minus green. So, according to them, the color pink is actually minus green.  In short, absence of green color is nothing but pink. I’ve attached the video below:

A Flashlight That Uses Body Heat Instead of Batteries

By Anupum Pant

I talked about a light that utilizes the power of gravity to light up a few days back. This flashlight is a bit similar in a way that, it also doesn’t need any batteries. But the underlying mechanism it uses, is completely different.

The winner of this year’s Google Science Fair, in the age group of 15-16, was a 15-year-old girl from Canada, Ann Makosinski. In her project she created a flashlight that, instead of batteries, uses our body heat to light up. She calls it “Hollow Flashlight”

The flashlight uses 4 Peltier tiles to convert the temperature difference (between body and room temperatures) into energy. One side of the tiles is heated by our body heat and the other side is at room temperature. This temperature difference creates electricity using the Thermoelectric effect. The tiles used for this light need a minimum of 5 degree difference of temperature to work.

Peltier Tiles

Peltier tiles utilize thermoelectric effect to convert temperature difference into electricity. When there is a enough temperature difference, charge carriers move from hot area to the colder area. This separation of charges builds up a potential difference across the height of the tile. This potential difference can be used up for various things. In this case, it was used to light up LEDs.

Advantages: The amount of potential difference produced depends on the material. Peltier tiles are great because they are compact and they do not use any moving parts. Elimination of any moving parts eliminates wear and tear. They last long and do not need a lot of maintainance. However, their efficiency is not so great. So, they are used only where long life is essential.
The Voyager space probe and other deep space probes, where long life is of prime importance, use Thermoelectric generators (another image). The heat there is produced by a radioactive isotope. Implanted pacemakers which require long life also use it as a source of energy. All of them work utilizing the same effect – thermoelectric effect. The eco-fan, a wood stove fan, also uses the same effect in a very creative way.

Thermoelectric Generators have a very interesting history.

Dancing Drops of Water and Dipping Hands in Molten Metal

By Anupum Pant

When you sprinkle water on a hot pan, you’ll find that the droplets start dancing on the surface, as if there was no friction at all. From far, this effect looks a lot like water droplets on a lotus leaf (a super-hydrophobic surface). But, the physics behind this phenomenon is completely different. Read on to find out what is the mystery behind these dancing drops of water.

The Leidenfrost Effect

Why does this happen?
Unlike the drops on a lotus leaf, this happens at a particular temperature for a specific liquid. Different kinds of liquids display this effect at different temperatures.
For water, at a temperature when a small amount of water in contact with the pan gets heated enough to form a thin-film of vapor below the drop, water is no longer stuck on the pan (water sticks to some surfaces due to low surface tension). The drop has a thin vapor film below it which enables the drop to move around on the film. The formation of this vapor film is a continuous process, till the whole drop turns into water, one film at a time. This is called the Leidenfrost Effect.

Some liquids like liquid Nitrogen are extremely cold. At normal room temperature, they start boiling. A normal room’s floor is like a hot pan for liquid Nitrogen. So, it forms these dancing drops on a floor which is just at room temperature. You can try this yourself – If you can find some liquid Nitrogen, you can simply drop it on the floor and watch droplets moving effortlessly. They won’t stop moving!

Dipping hands in Liquid Nitrogen

The temperature of liquid Nitrogen is around -195 degree centigrade. It is one of the coldest substances and is used with extreme caution in industries and laboratories. If it touches you, your skin can easily get burnt. Yes, burnt – at extremely low temperature. It could probably also make the dipped limb useless for life. So, you shouldn’t try stuff with liquid Nitrogen at home.

But, it turns out, you can safely dip your hand in it for a small amount of time and return unharmed. Thanks to the Leidenfrost effect. Our hot-pan like hand – for cold liquid Nitrogen – makes a thin film of vaporized Nitrogen around the whole hand. This film, protects our skin from the ill effects of extremely cold temperatures. Still, there is no reason for you to try this. It has been done already.

The crazy duo from Myth Busters tried this with molten lead. It worked!  They, of course had to wet the finger with water – for the vapor film formation.

Water flowing uphill

Recently, an undergraduate research student group from the University of Bath found out a way to manipulate the movement of water on a specially designed surface, using this phenomenon. They found that machining ridges on the surface (and heating it) would make the thin vapor films under water droplets move in such a way, that they could use it to propel drops against gravity. They were able to demonstrate this by showing water moving uphill on a slope. It is enthralling to see it for yourself. I’ve attached their video below.

Prince Rupert’s Drop – Exploding Glass

By Anupum Pant

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What is it?

At first, a Prince Rupert’s Drop is an interesting yet harmless looking drop of glass with a long tail. It looks like a tadpole: [image]

It is no different from an annoyed person who refuses to let out his resentment – A slightest something might make him explode suddenly, but it isn’t easy to make him let it out. Confused? Read on…

Now, think of a glass drop that has immense amounts of potential energy stored inside it – It explodes (actually implodes) when the tail is disturbed, but it is impossible to hit it hard with a hammer and break it.

How?

A Prince Rupert’s Drop is formed when a drop of molten glass is suddenly dropped into a water bath. This quick cooling, solidifies the surface fast, while the inner part remains molten. Now, glass formed on the surface, being a poor conductor of heat doesn’t allow the inner part to cool quickly. When the inner part starts cooling, it tries to shrink and pulls the surface towards it. As a result, great amount of potential energy gets stored inside, in the form of stresses (stresses are seen using a polarized filter). This stored energy gets released when the tail is disturbed – It explodes into very tiny pieces of glass.

Toughened glass – a stronger variety of glass used in several places – also uses a similar technique to make strengthened glass.

On Wikipedia, a user asked about the possibility of utilizing the energy released from this explosion, being used to fire a bullet from a barrel. An interesting possibility, I must say.

The Name

Prince Rupert of Rhine did not discover the drops, but played a role in bringing them to Britain. He gave them to King Charles II, who in turn delivered them to the Royal Society for scientific study. Prince Rupert’s Drop was a widely known phenomenon among the educated during the 17th century – far more than now.

Watch it being explained better

Probably the best demonstration of this glass drop exploding is right here on the internet. Couple of months back, a YouTuber, Destin (Channel: SmarterEveryDay) posted a video demonstrating the physics behind it. He recorded  the progression of the explosive fracture using a hi-speed camera (at more than 100,000 frames per second) and calculated the speed of the fracture travelling through its tail (~ 1.5 miles per second). I’ve attached it below for you to watch.

Why is a Metal Plate “Colder” Than a Plastic Plate?

by Anupum Pant

No, it isn’t!

What is Cold?

According to the dictionary, a body at a relatively lower temperature, especially when it is compared to the temperature of a human body is described as a colder one. So, any object below the normal human body temperature – about 37 degrees Celsius – is a cold thing. But wait a minute!

When you touch an object, what does it tell you about the temperature of the object? Can you really judge if it is a cold one or a hot one? Unfortunately, our bodies aren’t thermometers, we are not so smart when it comes to judging the temperature. Consider the following case.

A book and a steel plate kept in the same environment for a long time attain the same temperature eventually (it is called thermal equilibrium). This can be checked by using a thermometer on both the objects. But, when people are asked to touch a metal plate and a book, they find the former to be much cooler. You can try this out yourself by touching different materials around you. You’ll see how some things ‘feel colder’ while the others feel warmer. A YouTube channel Vertasium conducted a social experiment to record this on camera. See the video below:

There is no cold – only heat

So, in the video, ice melts faster, if kept on steel plate than on a plastic plate, even when the steel plate ‘feels colder’. Common sense dictates that the colder thing is supposed to sustain the ice block for a longer time, just like your refrigerator does. So why does the opposite happen?

A better way to understand this ‘contradiction’ (not really a contradiction) can be this:

According to thermodynamics, simply put, everything has heat in it. So, even a cold ice block has some amount of heat stored in it (say, around 273.15 Kelvin or 0 degree Celsius). When one object comes in contact with other object, it loses or gains heat till their temperatures get equal or till they attain ‘thermal equilibrium’. Which object loses heat and which one gains it, is decided by their relative temperatures. In case of ice and steel, ice has a lower temperature than steel (assuming it isn’t already freezing out there). Therefore, here, ice gains heat from steel till they attain the same temperature and ice melts.

Side note: The ice is also in contact with a relatively ‘hotter’ atmosphere. Hence, it gains heat from there also. In this case, we are only concerned about the steel and ice interaction.

Why does it melt faster on steel?

There is a particular property which depends on the kind of material and is called thermal conductivity. This is the parameter which decides which objects lose heat quicker and which ones do it slower.

Here, for instance, steel has a higher thermal conductivity than plastic. Hence, the steel plate gives away heat to the ice block faster than a plastic block does. As a result, ice melts faster on a steel plate than on a plastic one.

Incidentally, this effect can also be used to explain why one plate feels colder than the other, in our hands. Think of it like this, the ice is replaced by our hand. So, a steel plate, due to its better thermal conductivity, draws heat faster from our hand than a plastic plate. This makes us feel that the steel plate is colder than the plastic one.

As checked by a thermometer, both the plates have the same temperature, our bodies are only fooled into believing that the thing we feel is temperature; it isn’t. None of the plates is actually colder than the other (according to the dictionary – see first paragraph). We don’t feel the temperature. What we feel is actually the rate of heat being drawn away from our hand. Faster an object draws heat, the colder it feels.

Understanding the Impending Helium Crisis

by Anupum Pant

There is too much Helium?

Helium is the second most abundant element in the observable universe, present at about 24% of the total elemental mass. Helium is also the second lightest element. So, 24% by mass is too huge a mass for a single light element. It equates to a measure that is probably millions of times more than what humanity could use up in millions of years. Close to about 12 times the mass of all the heavier elements combined, this element will almost never run out. But, that is only when we talk about the universe. Back in Earth, it is completely a different story.

Helium sources for us

On Earth, Helium is relatively rare. It amounts to only a 0.00052% volume of the earth’s atmosphere. Although 0.00052% is not too less, you also can’t consider it as an abundant element. Moreover, extracting Helium from air is almost 10,000 times more costly than fractional distillation (mentioned in the next paragraph). So, all that Helium in air is nearly useless to us till better methods of extraction are invented.
Thankfully, Helium is also present under the surface of the earth. The source of this kind of deposit is, radioactive decays which take place down there. It mixes with the natural gas and is lost to space, if released into the atmosphere. It is separated from natural gas using a process called fractional distillation – The best process to make Helium.

The largest known underground reserve estimated to contain about 10 billion cubic feet of Helium is a federal reserve (mostly under Texas and Kansas). For years US reserves had been the largest global suppliers of Helium (90%). Even today, these reserves contribute to more than 35% of the total global supply. The price of Helium coming from this source has remained almost unchanged for a long time. While during the same period (10 years) privately held Helium prices have tripled. The gap in prices is increasing every day, creating a big distortion in the market.

Helium Usage

Uses of Helium range from manufacturing smart phone screens (all LCD screens) to optical fibers (Internet cables) to health care (MRI scanners) to scientific research etc. [Uses of Helium]

The Problem

Since Helium has been made artificially cheap due to the Helium privatization act, it is popularly believed to be a cheap gas and is wasted a lot. Instead of using it up for important things, we consume it by filling up party balloons, distort voices and other entertaining activities. In fact, the warning issued by the Nobel Prize winner Robert Richardson that Helium could be depleted within a generation, seems to have had no effect on us. We still continue to waste a lot of Helium, release it into the air and keep losing it forever. Not many realize that it is a non-renewable resource.

We have almost reached a crisis already, but it was temporarily averted by the congress. In the future, after about 6-7 years, when the Federal Reserve stops supplying it (at below-market prices), it could be a big problem. I’m not very optimistic about market adjusting within such a small span either. In under a decade, we’ll probably see smart-phone prices, optical fiber prices and health care (MRI scans etc.) prices shoot up precipitously due to this artificial market distortion, if we do not start using Helium properly.

How Loud Can it Get?

by Anupum Pant

Wives and moms can scream really well. But is it loud enough to inflict physical pain? Can sounds get louder than a nuclear bomb? How much damage can a loud sound cause? How about mass extinction? Read on to find out the answers.

What is sound?

Sound, as most of us know is a longitudinal, mechanical wave. That means, it is just a series of pressure changes [compressions and rarefactions] in a particular medium. So, the property of sound is as good as the medium it uses to travel. For instance, sound cannot travel in a vacuum due to the absence of any medium, but it can travel much faster in solids than in air. That is the reason you can’t hear someone talking in space (yes, movies that show loud explosions in space, lie). Also, the faster speed of sound in steel rails is exactly the reason why, you can tell a train is approaching, if you stick your ears to the rails (do not try this on electric rails).

Two of the fundamental parameters that describe a sound wave in numbers are pitch and amplitude. Pitch is measured in hertz – we’ll talk about it some other day. But, the amplitude of a sound wave determines how powerful it is; greater the amplitude, louder the sound. The loudness of sound is measured in Decibels (abbreviated dB).

More about decibel scale

Like most other linear scales, Decibel isn’t as easy to understand. A 10 point rise in the dB scale can be visualized as a 10 times increase in the loudness. Adding dB levels of different sound sources also doesn’t really work, the calculation is much more complicated; the resultant loudness depends on the coherency of the source [See this decibel addition applet]. Also, the perceived loudness is obviously lesser as you go away from the sound. Normally, a decibel scale ranging from 0 dB to 130 dB is enough for measuring the loudness of most things. But, things can get louder…much louder.

To get an idea of the decibel scale: 10 dB is 10 times more powerful than 0 dB, not 10 points greater. Similarly, 20 dB is 100 times more powerful and 140 dB is 100,000,000,000,000 times more powerful than a o dB sound.

0 dB is the loudness of near silence (a mosquito 10 feet away), while 120 dB is the loudness of a loud car horn heard from 1 meter away. Humans can hear sounds starting from 0 dB. But it can be quieter than 0 dB [the world’s quietest room]. It measures record setting -9 dB and can literally drive you crazy. In fact, the longest someone stayed in that room was for 45 minutes.
On the upper side of dB spectrum, a whisper is around 15 dB, conversations range from 40 – 60 dB and a jet engine measures 130 dB on the decibel scale. Like I said before, the perceived loudness depends on your ear’s distance from the source, so the loudness of a lawnmower can range anything from 90 dB to as much as 110 dB if you stand 3 feet away from it. [see the Decibel chart]

90 Decibels or a sound as loud as only a raised voice can cause gradual hearing loss (Refer to the hearing safety chart here). While 140 dB can cause physical pain. After 150 dB (firecracker) sounds can be felt in the form of shock waves. The pressure difference they cause in the medium can actually be felt by your body.

Beyond Decibels

Since the loudness depends on the medium, the maximum loudness a medium can propagate is dependent on its density. Our atmosphere can do nothing more than 190 dB, that, by the way, is enough to make you deaf or cause death. Sounds in water can get louder. A pistol shrimp is able to create a 200+ dB sound at 97 km/h to stun or kill its prey by snapping claws really fast. This is a very short lived pulse which doesn’t carry enough energy to do us any harm.

For events like the Saturn V launch, volcanic explosion, nuclear bomb explosion, earthquakes, star-quakes the concept of sound doesn’t really apply anymore. They are measured in terms of the shock wave they produce using the Richter scale. On this scale, 9 means total destruction (8.2 was measured during the explosion of the largest bomb ever, Tsar Bomba). An earthquake or earthly event measuring 10 has never been observed.

However, in the universe beyond earth, the starquake on the magnetar SGR 1806-20 registered 22.8 to 32 on the Richter scale. The magnetar released more energy in one-tenth of a second than our sun has released in 100,000 years. An event which thankfully took place 50,000 light-years away from earth. Had it been even 10 light-years away, the energy released would have wiped off life on earth. [read this BBC article for more information on this event]