Showing posts with label Today I learnt. Show all posts
Showing posts with label Today I learnt. Show all posts

Wednesday, June 21, 2017

Wow , thats disappointing



The 40-Year Old Mystery of the "Wow!" Signal Was Just Solved. Background: In 1977, the sound of extraterrestrials was heard by human ears for the first time — or so people at the time thought. The Wow! Signal was detected by astronomer Jerry Ehman using Ohio State University’s Big Ear radio telescope. It is a radio signal detector that, at the time, was pointed at a group of stars called Chi Sagittarii in the constellation Sagittarius.

When scanning the skies around the stars, Ehman captured a 72 second burst of radio waves: He circled the reading and wrote “Wow!: next to it, hence the signal’s name. Over the last 40 years, the signal has been cited as evidence that we are not alone in the galaxy. Experts and laypeople alike believed that, finally, we had evidence of alien life.

For a very long time , this was the strongest candidate we had as proof of extraterrestrial intelligence. It could not be explained any other way. However, Professor Antonio Paris, of St Petersburg College, has now discovered the explanation: A pair of comets. The work was published in the Journal of the Washington Academy of Sciences.

These comets, known as  266P/Christensen and 335P/Gibbs, have clouds of hydrogen gas millions of kilometers in diameter surrounding them. The Wow! Signal was detected at 1420MHz, which is the radio frequency hydrogen naturally emits. Notably, the team has verified that the comets were within the vicinity at the time, and they report that the radio signals from 266/P Christensen matched those from the Wow! signal.

Monday, May 29, 2017

Pluto Is Still A Planet….

 

…in New Mexico !

As far as most of the world is concerned, poor Pluto got downgraded from planet to dwarf planet (or planetoid) back in 2006 when the International Astronomical Union revised their definition of what constitutes a planet. For the curious, Pluto was downgraded because it lacks enough gravitational pull to distinguish itself from other dwarf planets in similar nearby orbits.

Whatever the reason was for the change in Pluto’s classification, New Mexico’s House of Representatives was having none of it. For you see, the man who discovered Pluto back in the 1930s, Clyde Tombaugh, was a long-time resident and a former professor of astronomy at New Mexico State University. Regardless of what the international astronomy community had to say about the matter, the people of New Mexico had a very strong opinion about the matter. Kandilley, karimeen puttaakee ?

In 2007, the House of Representatives passed a resolution declaring that March 13, 2007 would be observed as Pluto Planet Day and that whenever Pluto is in such a position that it can be observed in New Mexico’s night skies it is, in fact, still a full-fledged planet.

Bonus Trivia: Because Clyde Tombaugh was born in Illinois, the Illinois State Senate passed a resolution in 2009 that asserted Pluto was “unfairly downgraded to a dwarf planet” by the IAU.

Sunday, May 14, 2017

Today I read about ETOPS certification for planes

 

“It’ll be a cold day in hell before I let twins fly long-haul over-water routes.” Those were the words of Lynn Helms—administrator of the Federal Aviation Administration during the Reagan administration. At the time, no commercial american airplane with two engines was allowed to fly anywhere farther than 60 minutes from a diversion airport. The belief was that, if one engine failed, the other could only safely fly the plane for about an hour, but this rule severely limited what smaller planes could do. On North Atlantic routes like New York to London, twin-engine planes could only fly in these areas but a direct route looked like this. The options were to either fly a twin-engine plane on an inefficient routing or fly a inefficient three or four engine plane. There was no place for long-and-skinny routes between smaller cities using smaller planes since airline couldn’t legally fly those smaller planes. This one simple rule changed the very way airplanes were built. Now, in the 60’s, this 60 minute regulation only applied to planes with two engines. Of course aircraft manufacturers could build quad-engine jets but those had to be huge for airlines to make their money’s worth with their high fuel consumption. The 747’s of the time could carry more than 400 passengers. They could therefore only fly on super high-demand routes like New York to London to have any hope of being full. In order to start flying more convenient non-stop routes from smaller markets, planes had to get smaller while still being legally allowed to hop the pond.

That’s where trijets came into play. With three engines, these planes weren’t subject to the same 60-minute regulation as twinjets. They could easily fly any transatlantic route. That’s why in the 70s or 80s, the long-haul jets you’d see at airpots were, for the most part, either 747’s or trijets like the DC-10.

This 60-minute regulation was inconvenient for Atlantic Crossings, but in the Pacific it actually changed how Hawaii developed. There are zero diversion airports between California and Hawaii so the route isn’t even close to covered under the 60-minute rule. As a result, airlines could only fly huge planes between the mainland and Hawaii which meant that planes could pretty much only fly to Honolulu. Puttakke puttakke karimeen puttaakkee. There was virtually no service between the other islands and the mainland which meant the other islands were severely isolated. That’s part of the reason why the tourism industry only picked up on the other islands in recent decades. Luckily, change was coming. The 60 minute rule originated from the days of piston driven propeller aircraft.

With these, it was far more common for engines to just stop working mid-flight. That’s why there were contingency engines. The regulations just didn’t adapt to the increased reliability of jet engines. Statistically, for every failure of a jet engine, there are 117 piston engine failures. Once the jet age rolled in, engine failure just wasn’t as much of a concern, so, in 1985, the FAA begrudgingly granted permission to Trans World Airlines to fly their twin-engined

767 direct between Boston and Paris—a route taking it up to 120 minutes away from diversion airports. This was the first example of a brand new FAA certification called ETOPS—“Extended-range Twin-engine Operational Performance Standards,” or more colloquially, “engines turn or passengers swim.” Before an airline can fly a long over-water route they have to buy a plane with what’s known as an ETOPS type rating. Basically that means that the plane was built with adequate redundancies, communications systems, and fire suppression systems to fly safely if one engine fails. For example, the 767—the first plane to get an ETOPS certification—has a type rating of 180 minutes meaning it can fly anywhere as long as its 180 minutes from a diversion airport.

But just because a plane has a type rating doesn’t mean an airline can fly it ETOPS. They have to have a special maintenance plan, a special flight crew, special cabin crew, special dispatchers, special fuel quantities, and special passenger recovery plans since, just because there’s a runway doesn’t mean that a plane can safely divert since the emergency doesn’t end once the plane lands. Cold Bay, Alaska, for example, is a perfect diversion airport for routes between Asia and North America. It only has six commercial flights per week nowadays but as a former Air Force Base it has an enormous runway. The only issue is that the town of Cold Bay has a population of 108—its tiny—so any diversions automatically double or triple the amount of people in the small town. There certainly aren’t enough hotel rooms or restaurants to house and feed stranded passengers so, if airlines plan to use Cold Bay as a diversion airport, they need to make a plan for how to house, feed, and recover passengers within 48 hours of landing. Last year an American Airlines 787 was flying from Shanghai to Chicago when its right engine had an issue halfway across the Pacific Ocean. The plane quickly took a left turn diverting to Cold Bay. Even before landing the plan was implemented as flight attendants served a second meal service early. Just a few hours after safely landing in Cold Bay, American’s mechanics took off from Seattle bound for Cold Bay to start fixing the plane while Alaska Airlines, American’s partner, sent a 737 from Anchorage to pick up the stranded passengers. Meanwhile, flight attendants served the third set of meals they had stocked while waiting on the ground and the coast guard opened their heated hanger to passengers.

Just 10 hours after the emergency landing, passengers were on their way to Anchorage where they spent the night before taking an American 757 to Chicago. That was a perfect example of how the passenger recovery plan worked. The quick response and defined plan helped the airline get passengers out safely and quickly. Now, because of the solid engine reliability, numerous redundancies, and well-designed passenger  recovery plans, airlines and airplanes can now receive insane ETOPS certifications. The 787 Dreamliner, the plane that diverted to Cold Bay, has a type rating of 330 minutes. That means it can fly up to 5.5 hours away from a diversion airport. Certain routes over long-ocean stretches in the southern hemisphere were theoretically possible in the past with four engine planes but were economically impossible since airlines could never fill the large planes on the low-demand city pairs like Melbourne to Santiago.

With the ETOPS 330 certification, LATAM Airlines can fly their small 787 economically on this relatively low-demand route across the South Pacific. The Airbus a350 is even rated for ETOPS 370—it can fly 6 hours and 10 minutes away from diversion airports. This plane can therefore fly everywhere on earth except directly over the South Pole. Because of this simple rule change, three and four engine planes are largely a relic of the past. Boeing and Airbus’ largest jets are both their only four engine planes in production—the 747 and a380. Nearly all North Atlantic traffic today is on twin-engined planes as smaller and smaller planes get ETOPS certifications. Air Canada, for example, flies their tiny 120 passenger a319 with ETOPS certification daily between St Johns Airport and London Heathrow. British Airways even sends the even smaller a318 between New York and London City Airport. These routes would have been unimaginable 30 years ago but the reliability of the airplanes of today mean we need not fear flying small planes over big oceans.

Saturday, August 13, 2016

United States Wins 1,000th Olympic Gold Medal

 

The United States won its 1,000th Olympic gold medal on Saturday when the American women swimmers won the 4x100 meter medley relay at the Rio Games.  Not 1000 medals. 1000 Gold medals !

 

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Now that’s just awesome ! This is due to the high importance given to all kinds of sports there.

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Tuesday, April 26, 2016

Its Flipkart’s own Fault

 

Today I read a fantastic, long and detailed article on Flipkart’s past, present and future. Although many people and media have tried to explain Flipkart’s business and strategy in the past, this is by far the most detailed one I have read. A rather long read, the author explains that Flipkart had essentially painted itself into a corner, dug its own pit, and now  on one side they will see more competition from Amazon, on the other side, their own investors are asking for results. It was a series onfortunate decisions and the chaotic Indian market place which lead to this.

Flipkart’s decision to go app-only was the single most stupidest decision which came out from those brilliant minds. Having worked in CRM all my career, I can vouch that such customer un-friendly decisions is going to piss them off, when what customers expect is for you to listen to them. And their Billion days sales, the first time it happened, media loved it. The second time, they got smart and figured out that Flipkart was artificially inflating the price of products, and then giving a discount on that price, thus fooling the customer to spend more.

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And then there is the really big problem of the dollar- rupee ratio. When VCs fund Indian companies, they spend in dollars, but earn in rupees ! They have to sell 50 times more to make the equivalent same.

But I think the biggest hurdle they have, and all internet-startups for that matter, is the chaos that is India. The Indian market place is incoherrent and punishing. The Indian customer is slow and thinks a lot before making a purchase. And there is brand loyalty. Customers will go entire days deal hunting even for the smallest purchase.

Anyway, its a fantastic read, if you want to learn from others mistakes and avoid them on your own venture, go gobble it up.

Wednesday, March 9, 2016

The Primary Function Of Water Towers Is…..to pump Water !

 

I didn’t know this. All these years I used to look up at water towers and say “Why did they have to build them that tall ?” Here in India, water towers are used primarily as…landmarks ! The Koramangala water tank is well known, then there is the Sankey water tank. But today I learned that the reason of building the water reservoir on a tower is to let gravity act on it, and the water pressure thus created will let the water rise up into higher floors in buildings. Look at the diagram:

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At first glance, it would be easy to assume that water towers exist to store water. They are, after all, giant above ground vessels filled with anywhere from tens of thousands to millions of gallons of water.

But whether you’re talking about a modest little water tower perched atop an apartment building in New York City or a giant municipal water tower, water storage is not the primary function of the tower (if water storage was the only goal, it would be significantly cheaper to build a reservoir). The primary function of water towers is to pressurize water for distribution. Elevating the water high above the pipes that distribute it throughout the surrounding building or community ensures that hydrostatic pressure, driven by gravity, forces the water down and through the system.

The design helps keep the cost of water distribution lower for two reasons. First, it allows for centralization of pumping and pressurization, and decreases the number of pumping stations needed in the vicinity of the water tower. Second, it allows the water company to pump water up to the tower during off-peak energy times to decrease the expense of running the pumps.

Tuesday, September 15, 2015

How the Speed of Light was first measured

 

 

The speed of light in a vacuum stands at “exactly 299,792,458 metres per second“. The reason today we can put an exact figure on it is because the speed of light in a vacuum is a universal constant that has been measured with lasers; and when an experiment involves lasers, it’s hard to argue with the results. As to why it comes out somewhat conspicuously as a whole number, this is no coincidence- the length of metre is defined using this constant: “the length of the path travelled by light in vacuum during a time interval of 1/299,792,458 of a second.”

Prior to a few hundred years ago, it was generally agreed or at least assumed that the speed of light was infinite, when in actuality it’s just really, really, really fast-  for reference, the speed of light is just slightly slower than the fastest thing in the known universe- a teenage girl’s response time if Justin Bieber were to say on Twitter, “The first to reply to this tweet will be my new girlfriend.”

The first known person to question the whole “speed of light is infinite” thing was the 5th century BC philosopher Empedocles.  Less than a century later, Aristotle would disagree with Empedocles and the argument continued for more than 2,000 years after.

One of the first prominent individuals to actually come up with a tangible experiment to test whether light had a speed was Dutch Scientist, Isaac Beeckman in 1629. Despite living in a time before lasers- which gives me the chills just thinking about- Beeckman understood that, lacking lasers, the basis of any good scientific experiment should always involve explosions of some kind; thus, his experiment involved detonating gunpowder.

Beeckman placed mirrors at various distances from the explosion and asked observers whether they could see any difference in when the flash of light reflected from each mirror reached their eyes. As you can probably guess, the experiment was “inconclusive”.

A similar more famous experiment that didn’t involve explosions was possibly conducted or at the very least proposed by Galileo Galilei just under a decade later in 1638. Galileo, like Beeckman also suspected that the speed of light wasn’t infinite and made passing references to an experiment involving lanterns in some of his work. His experiment (if he ever conducted it at all), involved placing two lanterns a mile apart and trying to see if there was any noticeable lag between the two; the results were inconclusive. The only thing Galileo could surmise was that if light wasn’t infinite, it was fast and that experiments on such a small scale were destined to fail.

It wasn’t until Danish Astronomer, Ole Römer entered the fray that measurements of the speed of light got serious. In an experiment that made Galileo flashing lanterns on a hill look like a primary school science fair project, Römer determined that, lacking lasers and explosions, an experiment should always involve outer space.  Thus, he based his observations on the movement of planets themselves, announcing his groundbreaking results on August 22, 1676.

Specifically, while studying one of Jupiter’s moons, Römer noticed that the time between eclipses would vary throughout the year (based on whether the Earth was moving towards Jupiter or away from it). Curious about this, Römer began taking careful notes about the time I0 (the moon he was observing) would come into view and how it correlated to the time it was usually expected. After a while, Römer noticed that as the Earth orbited the sun and in turn got further away from Jupiter, the time Io would come into view would lag behind the expected time written down in his notes. Römer (correctly) theorised that this was because the light reflected from Io wasn’t travelling instantaneously.

Unfortunately, the exact calculations he used were lost in the Copenhagen Fire of 1728, but we have a pretty good account of things from news stories covering his discovery and from other scientists around that time who used Römer’s numbers in their own work. The gist of it was that using a bunch of clever calculations involving the diameter of the Earth’s and Jupiter’s orbits, Römer was able to conclude that it took around 22 minutes for light to cross the diameter of Earth’s orbit around the Sun.  Christiaan Huygens later converted this to more commonplace numbers, showing that by Römer’s estimation, light traveled at about 220,000 kilometres per second.  This figure is a little off (about 27% off) from the figure noted in the first paragraph, but we’ll get to that in a moment.

When Römer’s colleagues almost universally expressed doubt in his theory about Io, Römer responded by calmly telling them that Io’s 9th of November eclipse in 1676 was going to be 10 minutes late. When the time came, the doubters stood flabbergasted as the movement of an entire celestial body lent credence to his conclusion.

Römer’s colleagues were right to be astounded in his estimation, as even today, his estimation of the speed of light is considered to be amazingly accurate, considering it was made 300 years before the existence of both lasers, the internet, and Conan O’Brien’s hair. Okay so it was 80,000 kilometres per second too slow, but given the state of science and technology at the time, that is remarkably impressive, particularly given he was primarily just working off a hunch to begin with.

What’s even more amazing is that the reason for Römer’s estimation being a little too slow is thought to have less to do with any mistake on his part and more to do with the fact that the commonly accepted diameter of the Earth’s and Jupiter’s orbits were off when Römer did his calculations. Meaning yes, Römer was only wrong because other people weren’t as awesome at science as he was. In fact, if you slot the correct orbit numbers into what is thought to be his original calculations from reports before his papers were destroyed in the aforementioned fire, his estimation is nearly spot on.

So even though he was technically wrong and even though James Bradley came up with a more accurate number in 1729, Römer will go down in history as the guy who first proved that the speed of light was not infinite and worked out a reasonably accurate ballpark figure on what the exact speed was by observing the movements of a speck orbiting a giant ball of gas positioned about 780 million kilometres away. That right there ladies and gentlemen is how a badass, lacking lasers, does science.