hey guys its professor Dave, let's talk about quantum mechanics
so we've seen how the first steps into quantum theory gave us the idea that all energy is not
continuous but quantized, and that light obeys wave particle duality. the next
idea came courtesy of Louis de Broglie. pardon my poor French pronunciation. he
reasoned that if waves can behave like particles then particles must also
behave like waves. in his de Broglie relation he showed that the wavelength
of a particle is inversely proportional to its mass so we must now understand
that all matter has a wavelength, from subatomic particles all the way up to
your body and even a star. a macroscopic object like a baseball will have a
wavelength that is trillions of times smaller than the nucleus of an atom so
we don't need to think of baseballs as waves. Newtonian mechanics work just
fine to talk about the motion of objects we can see. but an electron has a
wavelength that is very significant compared to its actual size so we can no
longer think of electrons as particles, we must think of them as both a particle
and a wave
wave particle duality just got extended from light to matter
Erwin Schrodinger wanted a way to describe the wave mechanics of the
electron so he developed quantum mechanics to do just that. and as a
result we can no longer think of an atom as electrons revolving around a nucleus
the way planets revolve around a star
we have to think of an electron as a cloud of probability density that
represents regions where the electron can be found. Werner Heisenberg soon
showed that as a result of quantum mechanics there are fundamental
limitations to what we can know about a particle like an electron so he
formulated his uncertainty principle. the main ramification for chemistry is that
the more we know about the location of an electron the less we know about what
it's doing or its momentum. the more we know about what it's doing the less we
know about its location. this has nothing to do with the limitations of our
measuring instruments, it is an inherent quality of the electron. if we could know
both its location and momentum with complete certainty than we could
describe it as merely a particle but it is not a particle, it is both a particle
and a wave. this seems to defy common sense so how can it be true? we have to
get used to the fact that common sense doesn't make for good science. nature is
governed by mathematical equations, not by human perceptions of how things
should be. so when the math says that electrons are both particles and waves
or that space is curved around massive objects, or that time flows at different
rates for different observers, we have to accept that this is a deeper tier of
reality than what we can immediately perceive and comprehend. it seems like
common sense that the sun goes around the earth which is why we believed it
for so long, but mathematical calculations made by several astronomers
forced us to accept that it is the earth that goes around the sun, because their
model predicted the locations of celestial objects with more precision. we
can't look back at the solar system from afar, but we don't have to. the math is
the evidence. it is our understanding of mathematics that allows us to transcend
our five senses
and discover the true nature of the universe, from the tiniest particles to
the galaxies and beyond
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