Mysterious Hole in Guatemala City

On the 23rd of February 2007, a 330 foot deep sinkhole swallowed up over a dozen homes in a crowded neighborhood in Guatemala City. Over 1000 people were evacuated and two people were killed. The giant hole emitted a foul stench, tremors and loud noises. The authorities blamed the sinkhole on a ruptured underground sewage flow. Sinkholes are caused by changing geological conditions or by a failure to maintain aging underground pipes and sewage systems, but the common factor in both is usually water. Ground underlain with carbonate bedrock - limestone for example - is most prone to sinking because the bedrock erodes with repeated exposure to water. The rock corrodes and the sediment swells with water and eventually everything reaches a critical mass point. The sinkhole phenomenon appears to be intensifying all over the world as ground water continues to face depletion and earthquakes weaken substrata layers of earth.

Here's a local news report on the incident.

Shock Collar

I came across this term while I was searching for some astronomy news across the Internet. I found this to be an interesting fact which I thought I'll share it here. What is Shock Collar. Let's see what Wikipedia explains.

The Prandtl–Glauert singularity or P.G. singularity is sometimes referred to as a vapor cone, shock collar, or shock egg. The point at which a sudden drop in air pressure occurs is generally accepted as the cause of the visible condensation cloud that often surrounds an aircraft traveling at transonic speeds. It is an example of mathematicaly singularity (I don't know what that exactly means. So anyways...). Here are some of the pics of shock collar.

I found only three good pics of Shock Collar as there aren't many.

Interference With Eclipse

Here is one of the most spectacular picture taken during the Partial Solar Eclipse on July 22nd, 2009 at Hong Kong. The picture shows a very rare and unusual pattern of sunlight. The pattern seen here is known as the Interference Pattern. This is caused due to the superposition of the direct sunlight and the light reflected from the  window grids of the building on the left. (To know more about Superposition of light, check your 12th Physics Book ). This picture was taken from the 27th floor of a building.

How Does a Gun Silencer Work?

Well, I was watching so many action movies but every time I see a gun with a silencer I can't stop wondering how it works. As usual I checked on the net and Bingo! I got the answer. But the answer was amazingly simple. There is absolutely no mechanism in a silencer.

All that's required is that, the silencer should be slightly bigger than the gun barrel. That's all it takes to mute the firing sound (not exactly mute though). Well, I'll use the same example as I got through.

Imagine a balloon filled with air. You pop it with a pin and it burst making a huge sound. That is because the air pressure inside the balloon is very high and when the balloon pops, there is a huge drop in the pressure in a very quick time, creating the sound. But when you remove the end of the balloon, the air pressure reduces slowly and hence the sound is very less.

Similarly, in a gun, the gun powder is ignited behind the bullet. The gun powder produces a high pressure pulse of hot air. And as the bullet is out of the barrel, so is the air behind it. The air pressure in the barrel is around 3000 pounds per square inch (psi). So you hear the sound as there is a huge drop in the pressure. But in case of a silencer, when the bullet is out of the barrel, the air is released into a slightly larger volume and hence there is no huge drop of pressure but a considerable one. When the bullet is out of the silencer, the pressure is only 60 psi. Hence the firing sound is so much reduced.

Simple, yet effective!

Nikola Tesla vs Thomas Edison

I was watching the movie 'The Prestige', which is a story of two magicians. The movie also involves the lives of the inventors Thomas Edison and Nikola Tesla. According to the movie, Tesla hides from Edison and Edison is interested in destroying Tesla's works. I surfed through the net to find out about these two men and this was what I found.


Thomas Edison is well known for his invention of Direct Current (DC). But what about Nikola Tesla? Have you ever heard of the inventor 'Tesla' or any of his inventions? The only time one might have heard of him in text books is 'Unit of Magnetic Flux Density', which is named after him.

Check through the encyclopedia and find out who discovered the following.

Who discovered Radio? Marconi?
Who discovered X-rays? Roentgen?
Who discovered Vacuum Tube Amlifier? De Forest?
Also check on who discovered the fluorescent bulb, neon lights, speedometer, the automobile ignition system, and the basics behind radar, electron microscope, and the microwave oven.

Very little would the name Tesla be mentioned in these cases, thanks to Edison.

Tesla worked as an assistant to Edison at first. Edison had just invented the electric light bulb, but he needed a system to distribute electricity to houses. He designed a DC (direct current) system, but it had many bugs in it. Edison promised Tesla lots of money in bonuses if he could get the bugs out. Tesla took the challenge and ended up saving Edison over $100,000, which was millions of dollars by today's standards. Edison later refused to keep his promise. Tesla quit not long after that, and Edison spent the rest of his life trying to discredit Tesla (which is the main reason why he is so unknown today).

But there is a huge hidden stories which you would never come across in any books. Visit this page to know more about Tesla and his discoveries.