How long is a meter

[Donald]

Most people know a meter is about a yard but did you know:

Since 1983, the metre has been officially defined as the length of the path travelled by light in a vacuum during a time interval of 1/299,792,458 of a second.

New knowledge to this 70 year old brain to store. But how to bring the topic up at a cocktail to talk about?

 

[goingplacesanddoingstuff]

Presuming the speed of light in a vacuum is constant…

 

[Donald]

Presuming the speed of light in a vacuum is constant…

Everyone knows Warp 1 is a constant speed.

 

[Astro14]

Presuming the speed of light in a vacuum is constant…

Why would it not be?

Look, this definition borders on a tautology.

The speed of light* is defined in meters/second.

Meters are defined by seconds/the speed of light.

*The speed of light in a vacuum, commonly denoted c, is a constant, defined as 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour

 

[ecotourist]

A meter = 39.37 inches (close enough).

 

[Astro14]

A meter was once defined as 1/10,000,000 of the distance from Earth’s pole to the equator.

 

[goingplacesanddoingstuff]

Why would it not be?

Look, this definition borders on a tautology.

The speed of light* is defined in meters/second.

Meters are defined by seconds/the speed of light.

*The speed of light in a vacuum, commonly denoted c, is a constant, defined as 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour

This topic is a can of worms, but it boils down to parsimony. It’s both convenient and parsimonious to assume that c is constant, but there is no actual proof that it is or is not. It borders on non-falsifiable, and gets very touchy… just like the question of whether the rate of flow of time, as we perceive it, has been, is, and will be constant.

 

[Passport1]

A meter is 2X the distance from this computer screen to my eye balls.

 

[twX]

A meter is 2X the distance from this computer screen to my eye balls.

If you measured that by turning your monitor on and using a stopwatch, I'm impressed.

 

[Passport1]

If you measured that by turning your monitor on and using a stopwatch, I'm impressed.

My measurements aren't that precise. Just an estimate.

 

[Donald]

So what did they decide on first. How long a meter is? How fast was the speed of light? How long a second was? Something had to come first.

I think George Washington did surveys in rods.

 

[Blueshound]

Just take the number of feet, double it and add 30.

 

[Leo99]

I think I recall that a meter was officially defined as the length of of a special metal bar archived in some vault in France.

I'm a big metrology fan. I've had to break away from it at work as my responsibilities expanded but I do love metrology.

 

[Jetronic]

I think I recall that a meter was officially defined as the length of of a special metal bar archived in some vault in France.

I'm a big metrology fan. I've had to break away from it at work as my responsibilities expanded but I do love metrology.

It was, but they are going with all new definitions, not dependant on objects like that. The length is the same though, at the proper temperature.

 

[BHopkins]

So what did they decide on first. How long a meter is? How fast was the speed of light? How long a second was? Something had to come first.

I think George Washington did surveys in rods.

Interesting fact. Until 1960, a meter was defined by a physical artifact, of two marks inscribed on a platinum-iridium bar. I did not know what @Astro14 shared above, defining the physical size of a meter in relationship to the earth's size.

A meter = 39.37 inches (close enough).

Since the inch was shortened several decades ago, in an effort to unify standards of measurement, so that the inch is now precisely 25.4 mm, it would be more correct to say that a a yard = 0.9144 meters.

Interesting fact, in the early 14th century an inch was defined as “three grains of barley, dry and round, placed end to end lengthwise.” It sounds like historically speaking, the meter was based upon a much better constant.

 

[BHopkins]

I think I recall that a meter was officially defined as the length of of a special metal bar archived in some vault in France.

I'm a big metrology fan. I've had to break away from it at work as my responsibilities expanded but I do love metrology.

Yes, the historical physical meter is still stored in an environmentally controlled room somewhere in Paris.

 

[Astro14]

So what did they decide on first. How long a meter is? How fast was the speed of light? How long a second was? Something had to come first.

I think George Washington did surveys in rods.

Meter came first.

Just after the French Revolution, when they were looking to break with the past.

 

[JeffKeryk]

Well, a meter stick is what the Nuns used to instill discipline in me with. They gave it their best...

 

[BHopkins]

Well, a meter stick is what the Nuns used to instill discipline in me with. They gave it their best...

You brought tears to my eyes!

 

[Warstud]