|How small can things get?|
|Question Date: 2017-10-14|
The observable level:
water --> water molecule --> atoms (two Hydrogen
atoms and one Oxygen atom, size is about 1
Angstrom or 10-10 meter)
Not directly observable level:
atom --> nucleus (10-4 Angstrom) +
electrons (10-6M Angstrom) -->quarks
(below 10-8 Angstrom) --> Strings ?
--> Planck length (10-35 meter)
Up to the quark level, it has been
verified. But even smaller scale, it is beyond the
detection limit for now (therefore, I put a
question mark over there). Hope we can get the
answers in the future.
People used to think atoms were the smallest
objects in the universe, but now obviously they
are not. The smallest particles that have been
found so far are quarks (protons, neutrons are
made of quarks). A quark is no bigger than
10-18 meter. Just to get an idea
of how small this is:
Suppose we amplify a quark to the size of a grain
of sand (10-3 meter), and amplify a man
by the same factor, then this man would be so big
that he could swallow the entire solar system like
We don't know. There is a law in quantum mechanics
that limits how small the location of something
can be based on how quickly it may be moving, but
this size is bigger than an atom for electrons,
yet electrons fit into atoms.
There are theories
about what quantum mechanics of space and time
might look like, and they would be very small
indeed, but it's hard to know whether these
theories are right or not because we lack the
technology yet do experiments to test them.
Things can get extremely small, and we now have
many ways of observing these extremely small
things! Things that make up our bodies, the
surroundings and naturally occurring objects in
space can get as small as 9.1 *
10-31 kilograms (an electron). For
reference, an apple has an average mass of 0.1
kilograms, so an apple, on average, has
1029 times the mass of an electron.
Things that are classified as alive can get
very small, too. A single bacterium has a diameter
on the order of micrometers, which are
one-one-millionth of a meter, or 0.00004 of an
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