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Today I learned that skills improved by participating here on scienceforums can, at least in some minor way, be helpful in the current virus situation. I joined a local initiative where students study

I found out you can be superstitious, but not a little bit stitious.

Today I learned that you only need 39 digits of π to calculate the circumference of the observable universe with a precision of one atom.

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Today I learned that a certain species of fish - orange-spotted tusk fish is capable of using tools. Specifically, it finds clams and smashes them against a certain kind of rock to get to the meat inside. This is from a 60 minute first episode of a BBC documentary entitled „Blue Planet 2” Stunning visuals, literally every frame of those 60 minutes could be framed and put on a wall. Plus Hans Zimmer made the soundtrack.

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Today I learned that you can measure the speed of light with a microwave oven and some chocolate.

You put some previously molten chocolate evenly spread out across a plate and place the plate in an oven with the integral plate of the oven upside down to prevent the chocolate from spinning while heating up. Put it on low for about 40 seconds and take the plate out. Since a microwave oven creates a standing wave which heats the chocolate unevenly, you get „hotspots” of molten chocolate on the plate. You take a toothpick and poke the chocolate to find the hotspots and leave the toothpics there - you just found the peaks of your wave. You now measure the distance between the toothpics sticking out of the chocolate with a ruler and multiply it by the frequency of the oven. Pretty awesome experiment especially for kids. A guy on youtube got an 0.3% error margin result which is very impressive considering the crude methodology of this measurement. Theres a youtube film explainig the whole thing, its in Polish but I’ll post it anyway for reference if anybody wants to see that the numbers really add up surprsingly accurately:

 

Edit: This is such a simple and cool experiment which you can perform in any kitchen without any lab gear and yields a wonderfuly accurate result. I wonder if any physics teachers are using this in class @swansont

Edited by koti
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Much of Puerto Rico has been without power for four months, and many of its citizens have relocated to the US, especially Florida. The Kotch brothers are funding a little aid for these displaced people to provide essentials, including English lessons. Seems odd, considering they think medicare expenditures are wasted, IIRC.

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13 hours ago, koti said:

Today I learned that you can measure the speed of light with a microwave oven and some chocolate.

You put some previously molten chocolate evenly spread out across a plate and place the plate in an oven with the integral plate of the oven upside down to prevent the chocolate from spinning while heating up. Put it on low for about 40 seconds and take the plate out. Since a microwave oven creates a standing wave which heats the chocolate unevenly, you get „hotspots” of molten chocolate on the plate. You take a toothpick and poke the chocolate to find the hotspots and leave the toothpics there - you just found the peaks of your wave. You now measure the distance between the toothpics sticking out of the chocolate with a ruler and multiply it by the frequency of the oven. Pretty awesome experiment especially for kids. A guy on youtube got an 0.3% error margin result which is very impressive considering the crude methodology of this measurement. Theres a youtube film explainig the whole thing, its in Polish but I’ll post it anyway for reference if anybody wants to see that the numbers really add up surprsingly accurately:

 

Edit: This is such a simple and cool experiment which you can perform in any kitchen without any lab gear and yields a wonderfuly accurate result. I wonder if any physics teachers are using this in class @swansont

As I understand, microwave ovens employs frequencies of electromagnetic radiation.  My presumption have been that to cook food this has primarily involved frequencies of sound.  For a novice, such as myself, could you briefly explain how the speed of light and electromagnetic radiation are linked?  

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28 minutes ago, DrmDoc said:

 For a novice, such as myself, could you briefly explain how the speed of light and electromagnetic radiation are linked?  

'Visible light' is just a range of frequencies in the Electromagnetic spectrum.

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49 minutes ago, DrmDoc said:

As I understand, microwave ovens employs frequencies of electromagnetic radiation.  My presumption have been that to cook food this has primarily involved frequencies of sound.  For a novice, such as myself, could you briefly explain how the speed of light and electromagnetic radiation are linked?  

Sound waves are really slow compared to electromagnetic waves (343 m/s) Electromagnetic waves (radio, microwave, visible light, UV, etc) all have the same speed which is refered to as the speed of light (300.000 m/s) 

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4 hours ago, koti said:

Sound waves are really slow compared to electromagnetic waves (343 m/s) Electromagnetic waves (radio, microwave, visible light, UV, etc) all have the same speed which is refered to as the speed of light (300.000 m/s) 

Today I learned how difficult it is to keep count of the zeroes.

299 792 458 m / s

 

It confuses matters even further when you realise that some folks use the ,  where others use the . to delineate the decimal point and the thousands separator.

In the UK 343 m/s is a bit faster than 300.000 m/s

The speeds are about 3E2 and 3E8 m/s.

Sound is roughly a million times slower than light

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3 hours ago, John Cuthber said:

Today I learned how difficult it is to keep count of the zeroes.

299 792 458 m / s

 

It confuses matters even further when you realise that some folks use the ,  where others use the . to delineate the decimal point and the thousands separator.

In the UK 343 m/s is a bit faster than 300.000 m/s

The speeds are about 3E2 and 3E8 m/s.

Sound is roughly a million times slower than light

I wrote „m/s” instead of „km/s” - it is a big difference and I stand corrected. I’m going to blame the „.” instead of „,” on typing from my phone but it is also a horrible error and I stand corrected here as well. Thank you for your usual accurate assistance John. 

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9 minutes ago, EdEarl said:

Today I learned quotes are sometimes written „km/s” instead of "km/s." Is there a reason other than culture/language differences?

It depends on your keyboard language preference. The English correct quotation marks are ”text” whereas my device is set to a different language where „text” is the correct quotation. I hope thats ok. 

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11 hours ago, DrmDoc said:

As I understand, microwave ovens employs frequencies of electromagnetic radiation.  My presumption have been that to cook food this has primarily involved frequencies of sound.  For a novice, such as myself, could you briefly explain how the speed of light and electromagnetic radiation are linked?  

Got an actual NASA engineer to confirm this.(turned out to be a lot easier than I thought)

Anyways, here's a video he suggested.

 

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Today I learned:

Quote

“For the first time in history, more people die today from eating too much than from eating too little; more people die from old age than from infectious diseases; and more people commit suicide than are killed by soldiers, terrorists and criminals combined.’” Yuval Noah Hariri

 

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Today I learned about the Mobius strip. It is a surface with only one side (when embedded in three-dimensional Euclidean space) and only one boundary. The Möbius strip has the mathematical property of being unorientable. It can be realized as a ruled surface.

375px-M%C3%B6bius_strip.jpg

A Möbius strip made with a piece of paper and tape. If an ant were to crawl along the length of this strip, it would return to its starting point having traversed the entire length of the strip (on both sides of the original paper) without ever crossing an edge.https://en.wikipedia.org/wiki/Möbius_strip

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Today I learned an Astronomical Unit (AU) is the average distance between Earth and the Sun, which is about 93 million miles or 150 million kilometers. Astronomical units are usually used to measure distances within our Solar System. For example, the planet Mercury is about 1/3 of an AU from the sun, while the farthest planet, Pluto, is about 40 AU from the sun (that's 40 times as far away from the Sun as Earth is). http://coolcosmos.ipac.caltech.edu/ask/301-What-is-an-Astronomical-Unit

https://en.wikipedia.org/wiki/Astronomical_unit

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To my mind, the interesting thing about the astronomical unit is that it was fairly widely used before anyone really knew how big it was.

http://curious.astro.cornell.edu/physics/62-our-solar-system/planets-and-dwarf-planets/venus/262-how-did-a-transit-of-venus-provide-astronomers-with-the-first-measurement-of-the-earth-sun-distance-intermediate

Another interesting issue is that the abbreviation AU is also used for Absorption Units (in spectroscopy) and for also fro Angstrom units (not everybody has an "Å" on their keyboard.)
The former issue can be resolved by context- only one of them is a unit of length.

The second can be resolved by asking "is it bigger than a breadbox?"

A similar approach can be taken with the distinction between the nanometre (nm) and teh nautical mile (nm)

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Today I learned, in terms of true depth,  the Kola Superdeep Borehole is the deepest borehole in the world. It  is the result of a scientific drilling project of the Soviet Union in the Pechengsky District, on the Kola Peninsula. The goal was to to drill as deep as possible into the Earth's crust. https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole

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5 minutes ago, Itoero said:

Today I learned, in terms of true depth,  the Kola Superdeep Borehole is the deepest borehole in the world. It  is the result of a scientific drilling project of the Soviet Union in the Pechengsky District, on the Kola Peninsula. The goal was to to drill as deep as possible into the Earth's crust. https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole

Why do you think it stopped there?

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