Screaming Coin and a Singing Spoon

By Anupum Pant

Dry ice, or Cardice – as British researchers call it, is a solid form of carbon dioxide. When carbon dioxide is cooled below temperatures of -78.5 degrees centigrade, the gas gets directly frozen into a solid form. -78.5 degrees centigrade is extremely cold, and handling dry ice without proper protection can be very dangerous – could cause frostbite / burns. The point being, it’s extremely cold.

Since it’s too cold compared to something at room temperature, even everyday objects at room temperature can make it vaporize. A simple metal coin at room temperature would feel like a hot pan to dry ice. So, when a coin is shoved into a piece of dry ice, it creates a funny sound, just like water would, on a very hot pan; or, you could say the sound be very much like a hot metal ball being dropped into a cold bath of water (the temperature difference being much less in this case, of course).

This is how it works: The metal piece at room temperature vaporizes some amount of carbon dioxide from the piece of dry ice when it comes in contact. There’s a pressure difference (Bernoulli’s principle) associated with this process and the gas tries to escape. This makes the metal vibrate very fast, creating that funny sound. This is how it sounds…

Metals work best because they have a good thermal conductivity. For the sake of trying it out yourself, if you have a piece of dry ice lying unused, you could dip a spoon in hot water and make it touch the piece of dry ice. A slightly warmer spoon will probably give you a better effect. And then the spoon will be singing…

The Natural Segmented Sleep

By Anupum Pant


The light bulb changed everything. Before it came, when the only practical sources of artificial light were candles & lamps, people did not often use candles to stay awake at night. These sources of artificial light costed a lot more per lumen hour. They were not always used. They were used only when artificial light was totally necessary. Normally, as the sun went down, people preferred sleeping. As bulbs came, they transformed the way we slept. Or, so argued the historian A. Roger Ekirch.

In his detailed published anthropological work – At Day’s Close: Night in Times Past – he mentions that the eight-hour single block of sleep is a recent change in our sleeping schedule. For many many years more than we’ve slept for eight hours in the night, our ancestors had practised a very different kind of sleep schedule which became the natural way of sleeping for humans. It was a segmented sleep.

The schedule went like this…

When the sun went down, there was more or less no artificial source of light. Due to this, our ancestors could do nothing useful. Bored with inactivity, they slept. Then somewhere in the mid-night, they woke up. For an hour or so, they remained awake and went back to sleep again till the morning.

The time for which these people remained awake, was probably the most relaxing and most calm time of their lives. Due to increased levels of pituitary hormone prolactin, people felt a lot at peace during this hour. During this time, people liked involving themselves in some kind of activity. Some preferred reading, others wrote. Some smoked, others visited their friends. And so on… The point is, people found themselves replenished during this time. It was apparently blissful.

This pattern of sleep became a natural way for us humans. Turns out, the eight-hour block of sleep is not the way we always used to sleep!

This sleep pattern has been observed to come back to today’s humans when they were completely deprived of any artificial light. This can be seen in the famous experiments of a psychiatrist, Thomas Wehr.


That waking hour of bliss – a fact of life before the industrial revolution came – was probably a period which I feel, needs to come back to cure the modern world’s rising anxiety, stress, depression, alcoholism and drug abuse.

Some scientists believe that if you give your bodies a chance, they’d go back to a segmented sleep pattern. This is also bolstered by Wehr’s experiments. While others prescribe you sleeping pills if you tell them you wake up at night for an hour or so.

Just for the record, I’m writing this at 2:30 AM. I just woke up, and I’m off to sleep again.

[Read more]

[Mastering Biphasic sleep] A detailed blogpost on the experience by Jayson Feltner…

Weight of the Copper Tube with a Falling Magnet

By Anupum Pant

Remember I talked about Copper tube and a magnet a couple of days back? Turns out the same happens when you use an aluminium tube too. In short, a magnet (a strong one – neodymium magnet) when dropped into an aluminium or copper pipe falls very slowly, as if gravity stops acting on it.

It is due to the opposing magnetic forces generated by the electric field which is in turn generated by the magnetic field of the magnet (more in the link above).

That said, have you wondered what happens to the weight of the tube when the magnet is falling? Does it increase, decrease or remain the same? Just give it a guess and watch the following video.

The Royal Institution Explains:

Hit like if you learnt something today.