If Earth was a grain of sand in Buenos Aires
in what point in this observable universe map would be LA be?
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$\begingroup$ Of order only ten light years away. $\endgroup$– uhohCommented Feb 7, 2020 at 23:22
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$\begingroup$ LA and BA both at the center. I don't get the question, to be honest. $\endgroup$– AlchimistaCommented Feb 12, 2020 at 10:37
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1 Answer
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The key to this kind of comparisons is to get a ratio. How much bigger is one number than the other?
From Buenos Aires to Los Angeles, there are nearly 10,000km. The size of a grain of sand varies a lot, but let's say it's a millimetre in diameter.
That's 4 orders of magnitude in the numbers themselves, then three orders of magnitude from there being a thousand metres in a kilometre, and three more from there being a thousand millimetres in a metre.
$=10^{10}$
This is how much larger the LA - Buenos Aires distance is than the diameter of that grain of sand. It is also how much larger the distance out in the universe is compared to the diameter of the Earth.
The Earth's diameter is a bit more than ten thousand kilometres, so after multiplication, we will end up with about $\approx 10^{14}km$. A light year is about $10^{13}km$, so we get out to the handful of closest stars.
answered Feb 8, 2020 at 11:25
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$\begingroup$ cs.mcgill.ca/~rwest/wikispeedia/wpcd/wp/s/Sand.htm provides some information of size for various types of sand. $\endgroup$– user21Commented Feb 9, 2020 at 17:24
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$\begingroup$ From that, the 1mm sand would be "coarse sand" $\endgroup$ Commented Feb 9, 2020 at 17:26