Tag: measurement

8 Million Years Later Our Descendants Will Receive Our Message

By Anupum Pant

Thanks to the LAser GEOdynamics Satellite or LAGEOS 1 developed by NASA, we can rest assured that a message ensconced in it will be received by our descendants 8 million years from now, when the satellite is estimated to crash land on Earth.

Note: LAGEOS 2 was a joint effort by NASA and ASI of Italy

Background

Structure: LAGEOS is basically a heavy metal ball measuring 60 cm in diameter containing no electronics or any sensors whatsoever. Its body is made up of aluminum and the internal core is made of brass. The brass core has been used to make sure that it weighs enough to do its job properly – the complete satellite weighs around 400 kg. The outer part is embedded with 422 reflectors. These reflectors make sure that the craft reflects back the light (laser) shone at it, to its source with minimum scattering.

Purpose: The primary purpose of the satellite isn’t to send a message to our future races, rather the satellite has been put up on orbit around the Earth to monitor several kinds of changes in long-term data like – exact shape of the planet, motion of tectonic plates, gravitational field measurement, measurement of the Earth’s wobble etc. This is done by sending laser pulses towards it from bases around the world located in US, Mexico, France, Germany, Poland, Australia, Egypt, China, Peru, Italy, and Japan. These laser pulses are reflected back to the Earth bases by those 422 reflectors. As the satellite has a very stable orbit, the measurement of time difference taken to send and receive the laser pulse gives away a lot of useful information.

 The message plaque:

Quoting from the NASA’s website:

LAGEOS 1 also contains a message plaque addressed to human and other beings of the far distant future with maps of the Earth from 3 different eras – 268 million years in the past, present day, and 8 million years in the future (the satellite’s estimated decay date).

The Coastline Paradox

By Anupum Pant

The length of Australia’s coastline according to two different sources is as follows:

  1. Year Book of Australia (1978) – 36,735 km
  2. Australian Handbook – 19,320 km

There is a significant difference in the numbers. In fact, one is almost double the other. So, what is really happening here? Which one is the correct data?
Actually, it depends. The correct data can be anyone of them or none of them. It completely depends on the kind of precision you decide to use while measuring the coastline. This is the coastline paradox.

The coastline paradox

The coastline paradox is the counter-intuitive observation that the coastline of a landmass does not have a well-defined length. – Wikipedia

The length of the coastline depends, in simple terms, on the length of scale you use to measure. For example, if you use a scale that is several kilometers long, you will get a total length which is much less than what you’d get when you would use a smaller scale. The longer scale, as explained neatly in this picture, will skip the details of the coastline.

This is exactly what happened when the two different sources measured the coastline of Australia. The first, Year Book of Ausralia, used a much longer scale than the one, Australian Handbook used. Ultimately, the great disparity in the result had to do with the precision of measurement. Had they used a scale just 1 mm in length, the result would have been a whooping 132,000 km.

This effect is similar to the mathematical fractal, Koch’s flake. Koch’s snowflake is a figure with finite area but infinite perimeter. Veritasium explains it better in this video:

Another factor is to take into account the estuaries to measure the length. Then,what about those little islands near the coast? and the little rocks that protrude out of the water surface? Which ones do you include to come out with the data?  And the majestic Bunda cliffs? Probably this article from the 1970’s clarifies what was included and what was not during the time the results were published.

So, the next time someone decides to test your general knowledge and asks you the length of certain country’s coastline, your answer should be – “It depends.”

10 Fancy Units of Measurement

by Anupum Pant

There exist a few unusual units of measurement which you must have never heard of, or would have never thought of them as units until now. Here is a list of 10 of the many fancy units of measurement.

Note: These units are not official. They’re often used for their humor value or for simplicity’s sake):

1. Car length – It is not a very unusual unit of measurement and is used normally to mention the braking distance of a vehicle. Deriving its length from a typical car’s length, 4 meters is referred as one “car length”. You must have heard one spy advising another spy to keep a 2 car length distance from a vehicle to avoid detection.

2. Nanoacres – A measure of area which is equal to about 4 sq.mm (4.0468564224 sq.mm exactly). It is the area of a single VLSI chip which is square in shape and measures 2 mm on each side. This unit is widely popular as a joke among electronic engineers – who often are known to make quips about VLSI nanoacres having costs in the same range as real acres.

3. Grave – It is a unit that measures mass and equals 1 kilogram or 1000 grams. Grave was set to be the standard unit of mass for the metric system, but it was replaced by kilogram in 1799. [read more about it]

4. Moment – Moment is actually something that was used to measure 90 seconds during the Medieval times. But for modern times, the Hebrew calendar’s definition of moment makes more sense. According to it, a moment is equal to 5/114 of a second or around 0.0438  seconds. [read more]

5. Jiffy – Jiffy is used popularly as an informal time in English. Think of someone saying “I’ll be back in a jiffy”. But, we’ve never thought of it as a unit. Also, every field has a different definition of Jiffy.

  • Early usage – 33.35 picoseconds or the time take by light to travel 1 cm.
  • Electronics – 1/50th or 1/60th of a second, depending on the AC power supply frequency.
  • Computing – Typically anything between 1 millisecond to 10 millisecond. Commonly: 10 ms.
  • Animation – The time interval between each frame of a dot GIF file or 1/100th of a second or 10 ms.
  • Physics/Chemistry – Time taken by light to travel 1 Fermi or 3X10^-24 seconds.

6. Dog Year – Based on a popular myth that dog’s age can be calculated in human years by multiplying it with 7. So, a single Dog year comes to around 52 days (365/7 – Days in a human year divided by 7)

7. A Bible – Used as measure of digital data volumes. It is like measuring the size of a disk in number of movies it can fit which I used in this article. A single Bible in uncompressed 8-bits, has around 4.5 million characters and 150 of them can be stored in a single CD. Hence, a bible can be measured to be approximately equal to 4.67 Megabytes. Similarly,  Encyclopedia Britannica and Library of Congress are used to represent much larger data volumes.

8.  Kardashian – Yes, it is named after the 72 day marriage of  Kim Kardashian to Kris Humphries. Of course, it measures 72 days of marriage. So, a 25 year marriage would amount to around 126.7 Kardashians.

9. Wheaton – Used to measure the number of twitter followers relative to the popular celebrity Will Wheaton. This became a standard when he had 0.5 million Twitter followers. Today, Will Wheaton himself has 4.88 Wheatons. I, for instance, with 210 followers, have about 0.00042 Wheatons.

10. Warhol – Derived from the widely used expression coined by Andy Warhol – “15 minutes of fame” – 1 Warhol measures exactly what you’d expect it to – 15 minutes of fame. Yes, it measures the amount of fame.
Consequently, 1 kilowarhol is equal to 15,000 minutes of fame or 10.42 days and 1 megawarhol measures 15 million minutes of fame or about 28.5 years.