4 ms·

Turn this around: How many people have seen the speed of light, even for a second? How many people have seen a kiloton of TNT being blasted? You're only advocat

by nayuki 4y ago

Turn this around: How many people have seen the speed of light, even for a second? How many people have seen a kiloton of TNT being blasted? You're only advocating for these units because they are commonly reported in the media and are thus familiar - at least in print, not in physical experience. Angstroms are needless jargon because nanometres already cover roughly the same scale. Do you want to go back to the bad old days when every town had its own definition of feet and pounds, and consumers were routinely cheated through the use of confusing and obfuscated units?

dotnet00 4y ago
People haven't seen the speed of light, but they have an understanding of the fact that it's the maximum possible speed. Similarly, while people haven't seen a kiloton of TNT being blasted, they can easily visualize what a kiloton of TNT is and understand what that means. Your claim that I'm only advocating these units because they're common in media is ignoring the fact that these are also very common as formal units in their respective fields. Another great example is AU, no one has seen what 1AU exactly is, but everyone can intuitively understand that 5AU means 5x further from the Sun than the Earth is, 0.74 terameters conveys absolutely nothing on its own and even for someone who is aware that 1AU=0.15 terameters, it takes a bit of extra mental effort to obtain the same information while not really adding anything because '1AU=0.15 terameters' is fundamental knowledge in the field anyway. This is not going back to the old days of units for two big reasons, they have important meaning within their field and there is widespread knowledge of conversion factors. Normalized units are also very popular in physics as they simplify the math and are more intuitive due to being directly tied to physical properties. Hell, even going back to the old metric vs imperial debate, there were very good benefits to the imperial system back when calculators were rare as multiples of 12s were more convenient to divide in the most common fractions (2, 3, 4, 6). Even now our clocks are based on those multiples due to their convenience for general use.
timr 4y ago
Angstroms stick around in chemistry and biochemistry because they're approximately the length of a carbon-hydrogen bond (~1.09Å), and therefore easy to reason about and talk about. Saying 1.09e-10 meters is fine, I guess, but it's a lot easier and more intuitive to think in terms of units of CH (plus 10%), especially when you're talking about more than one. Remembering that CH is about 1Å and CC is about 1.5Å is such a basic approximation that it's become universal.
zmgsabst 4y ago
Lots of people have seen the speed of light: 1ft per nanosecond. (Okay, 11.8 inches.) There’s also reasons that the speed of light is the “natural” speed to discuss large distances in — particularly astronomical ones. https://www.wolframalpha.com/input?i=%28speed+of+light%29*%281+nanosecond%29 https://www.wolframalpha.com/input?i=%28speed+of+light%29*%2...
djtango 4y ago
Angstroms are like cm - we could express everything as 10x mm or even 1/100 m, when you are deep in the subject matter having intuitive units facilitates communication by abstracting the 100pm or 0.1 to an A is helpful as that is the order of magnitude that covalent bonds exist within eg Bohr radius is roughly half an angstrom and width of H2 gas is just under 3A By expressing them in pm they actually lose some context as then they're all just numbers. Daltons is a similar concept that springs to mind

by nayuki 4y ago

dotnet00 4y ago

People haven't seen the speed of light, but they have an understanding of the fact that it's the maximum possible speed. Similarly, while people haven't seen a kiloton of TNT being blasted, they can easily visualize what a kiloton of TNT is and understand what that means. Your claim that I'm only advocating these units because they're common in media is ignoring the fact that these are also very common as formal units in their respective fields. Another great example is AU, no one has seen what 1AU exactly is, but everyone can intuitively understand that 5AU means 5x further from the Sun than the Earth is, 0.74 terameters conveys absolutely nothing on its own and even for someone who is aware that 1AU=0.15 terameters, it takes a bit of extra mental effort to obtain the same information while not really adding anything because '1AU=0.15 terameters' is fundamental knowledge in the field anyway. This is not going back to the old days of units for two big reasons, they have important meaning within their field and there is widespread knowledge of conversion factors. Normalized units are also very popular in physics as they simplify the math and are more intuitive due to being directly tied to physical properties. Hell, even going back to the old metric vs imperial debate, there were very good benefits to the imperial system back when calculators were rare as multiples of 12s were more convenient to divide in the most common fractions (2, 3, 4, 6). Even now our clocks are based on those multiples due to their convenience for general use.

timr 4y ago

Angstroms stick around in chemistry and biochemistry because they're approximately the length of a carbon-hydrogen bond (~1.09Å), and therefore easy to reason about and talk about. Saying 1.09e-10 meters is fine, I guess, but it's a lot easier and more intuitive to think in terms of units of CH (plus 10%), especially when you're talking about more than one. Remembering that CH is about 1Å and CC is about 1.5Å is such a basic approximation that it's become universal.

zmgsabst 4y ago

Lots of people have seen the speed of light: 1ft per nanosecond. (Okay, 11.8 inches.) There’s also reasons that the speed of light is the “natural” speed to discuss large distances in — particularly astronomical ones. https://www.wolframalpha.com/input?i=%28speed+of+light%29*%281+nanosecond%29 https://www.wolframalpha.com/input?i=%28speed+of+light%29*%2...

djtango 4y ago

Angstroms are like cm - we could express everything as 10x mm or even 1/100 m, when you are deep in the subject matter having intuitive units facilitates communication by abstracting the 100pm or 0.1 to an A is helpful as that is the order of magnitude that covalent bonds exist within eg Bohr radius is roughly half an angstrom and width of H2 gas is just under 3A By expressing them in pm they actually lose some context as then they're all just numbers. Daltons is a similar concept that springs to mind