Heisenberg's uncertainty principle
http://www.youtube.com/watch?v=a8FTr2qMutA (4+ min)
Heisenberg's uncertainty principle tells us that it is
impossible to simultaneously measure the position and
momentum of a particle with arbitrary precision. In our
everyday lives we virtually never come up against this
limit, hence why it seems peculiar. In this experiment a
laser is shone through a narrow slit onto a screen. As the
slit is made narrower, the spot on the screen also becomes
narrower. But at a certain point, the spot starts becoming
wider. This is because the photons of light have been so
localized at the slit that their horizontal momentum must
become less well defined in order to satisfy Heisenberg's
What is the Heisenberg Uncertainty Principle? - Chad Orzel
https://www.youtube.com/watch?v=TQKELOE9eY4 (4+ min)
The Heisenberg Uncertainty Principle states that you can
never simultaneously know the exact position and the exact
speed of an object. Why not? Because everything in the
universe behaves like both a particle and a wave at the same
time. Chad Orzel navigates this complex concept of quantum
Quantum vacuum fluctuation (or Quantum Fluctuation for short)
Quoting from the above Wikipedia page:
"In quantum physics, a quantum vacuum fluctuation (or
quantum fluctuation or vacuum fluctuation) is the temporary
change in the amount of energy in a point in space, arising
from Werner Heisenberg's uncertainty principle.
"According to one formulation of the principle, energy and
time can be related by the relation
"That means that conservation of energy can appear to be
violated, but only for small times. This allows the creation
of particle-antiparticle pairs of virtual particles. The
effects of these particles are measurable, for example, in
the effective charge of the electron, different from its
"In the modern view, energy is always conserved, but the
eigenstates of the Hamiltonian (energy observable) are not
the same as (i.e., the Hamiltonian doesn't commute with) the
particle number operators.
"Quantum fluctuations may have been very important in the
origin of the structure of the universe: according to the
model of inflation the ones that existed when inflation
began were amplified and formed the seed of all current
Quoting from A USENET Posting by Steve Carlip (UC Davis):
"CMB fluctuations give evidence for (though not proof of)
"So far, I haven't said anything about where the initial
density variations of the pre-recombination plasma came
from. There are many possibilities. We know, at least, that
they must be there -- even if we try to start with a
perfectly smooth, unvarying plasma, the Heisenberg
uncertainty principle tells us that there must be a minimum
level of quantum fluctuations.
"Inflationary" models propose that the very early Universe
-- before the time of primordial nucleosynthesis --
underwent a very rapid expansion. Such an expansion would
smooth out/dilute any earlier inhomogeneities, leaving only
the quantum fluctuations, which would be "stretched" in size
by the rapidly expanding space.
"Such models predict a special pattern of fluctuations. In
particular, although any particular fluctuation is random,
the average number at any particular scale is predictable.
This pattern on initial variations, in turn, should show up
in the details of the CMB variations. So far, observations
match the predictions of inflation very well. Most people in
the field don't consider this conclusive -- one can imagine
other ways of getting a similar pattern of initial
perturbations -- but it is suggestive."
Cosmic Inflation and the Accelerating Universe - Part 1 - Alan Guth
http://www.youtube.com/watch?v=HwCCMHH378Q (9+ min)
Alan H. Guth describes the theory of inflation and presents
evidence that indicates our universe very likely underwent a
perod of inflation in its early existence. He also discusses
the surprising observation that the expansion of the
universe is accelerating, offers possible explanations for
this acceleration, and describes its impact on particle
1. The density stays constant during inflation
2. The net energy is very small -- likely zero
Physics Nobel Prize 2011 - Brian Schmidt
http://www.youtube.com/watch?v=YHBvOOX3RJQ (7+ min)
The Nobel Prize for physics in 2011 was awarded to Brian
Schmidt, Adam Riess, and Saul Perlmutter for discovering
that the universe is expanding at an accelerating rate. This
finding was completely unexpected because it was thought
that gravity should slow the expansion of the cosmos. The
best current explanation of why the universe is accelerating
is that there is some energy tied to empty space which
pushes matter apart. This 'Dark Energy' makes up 73% of the
universe but is very difficult to detect.
The Trouble With “The Big Bang”
A rash of recent articles illustrates a longstanding confusion
over the famous term.
BY SABINE HOSSENFELDER
Why Is The Universe So Empty?
https://www.youtube.com/watch?v=CmqbMwRK8KA (4+ min)
We Have No Idea: A Guide to the Unknown Universe
by Jorge Cham; Daniel Whiteson
Humanity's understanding of the physical world is full of
gaps. Not tiny little gaps you can safely ignore-there are
huge yawning voids in our basic notions of how the world
works. PHD Comics creator Jorge Cham and particle physicist
Daniel Whiteson have teamed up to explore everything we
don't know about the universe: the enormous holes in our
knowledge of the cosmos. Armed with their popular
infographics, cartoons, and unusually entertaining and lucid
explanations of science, they give us the best answers
currently available for a lot of questions that are still
perplexing scientists, including:
* Why does the universe have a speed limit?
* Why aren't we all made of antimatter?
* What (or who) is attacking Earth with tiny, superfast particles?
* What is dark matter, and why does it keep ignoring us?
It turns out the universe is full of weird things that don't
make any sense. But Cham and Whiteson make a compelling case
that the questions we can't answer are as interesting as the
ones we can.
This fully illustrated introduction to the biggest mysteries
in physics also helpfully demystifies many complicated
things we do know about, from quarks and neutrinos to
gravitational waves and exploding black holes. With equal
doses of humor and delight, Cham and Whiteson invite us to
see the universe as a possibly boundless expanse of
uncharted territory that's still ours to explore.