

Stephen Hawking's explosive new theory - edw519
http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2008/06/26/scihawking126.xml

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ardit33
Ok, I will take a stab to explain it.

There are comparing the current universe, to light. Light is both a particle
and a wave, that means that photons exhibit both properties, and it all
depends on how you observe it. The other interesting part of light, as it
always chooses the path that takes the "shortest time". Not the shortest path,
but shortest time.

Eg. If you shot a laser beam thru ice, the laser beam will reflect to a
certain angle, b/c it is the quicker angle to get away from that material. Why
does light choooses this path? In quantum theory, it seems that light explores
ALL paths possible, (wave property), and we observe it in the shortest path
(as a particle), as it is the most likely to occur.

So, basically the are claiming the Universe is like light, a big giant wave,
with no beginning, and unlimited posibilities/paths, but we are observing only
one, the most likeley one.

When a particle travels, from point a, to b. It has a distinct begining, you
can pin-point it. That's the bing bang, if you thing of our universe as a
particle.

But if something both wave/particle properties, there is no distinct
beginning, as it is all around. You can observe it at certain points, but it
also can be in other points simultanosly, but you just observe one at a time,
but you can't pin-point it exactly.

...

One interesting experiment, about the wave/particle property, is the double
slit experiment: <http://www.youtube.com/watch?v=DfPeprQ7oGc>

Take mark of the last phrase: "Merely observing the particle, the observer
collapse the wave function, and made the particle act as solid". So, we are
the observers, the universe is the giant wave/particle thing, and by us
existing and observing it, we are collapsing to a concrete thing (to us at
least).

...

"At first, they found that the most probable history of the cosmos had only
undergone "a little bit of inflation at the beginning, contradicting the
observations," said Prof Hertog. Now, after a correction to take account of
how the data we have on inflation is based on only a view of a limited volume
of the universe, they find that the wave function does indeed predict a long
period of inflation."

In other word, let's fudge some math here, some there, and re-arrange some
stuff there, to have the data to support our hypothesis. Unfortunately it is
hard to know if this is right, b/c it is just one of the so many theories.

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markm
Is it OK to admit I don't get it?

~~~
bgutierrez
When I'm on my death bed, not having learned enough physics will be my
greatest regret. I hope.

~~~
ovi256
If you trust popular wisdom, you surely will not regret not working enough.

Carpe Diem.

~~~
Luc
But learning physics _is_ carping the diem - it's what I would be doing if I
wasn't working.

~~~
harry
Hear hear! Dumb work preventing further piddling away in astrophysics classes.

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Allocator2008
Hard to tell from the article which kind of skimmed over stuff, from what I
can tell, the theory posits we live in a large, isotropic, semi-classical
world following a long (more than Plankian scale) epoch of inflation, because
a large sub-set of vacuum states in the landscape of vacuum states in string
theory are such that they will lead to long periods of inflation, thereby
producing large, isotropic, semi-classical post-inflationary regions such as
the one we observe. I suppose if one can demonstrate a large subset of the
possible histories in string theory lead to alot of inflation, one can say it
is "most probably" to find oneself in a history that has had a lot of
inflation. I suppose earlier versions of the Hartle-Hawking "sum over
histories" approach didn't take the string theory "landscape" into account,
and this theory in the article is "new" in the sense that it is the same "sum
over histories" approach, but attacked from the viewpoint of the string theory
landscape, attempting to demonstrate how one can get inflation from some non-
vanishing subset of histories associated with the string theory landscape. But
I haven't seen the actual paper, so not quite sure if this is exactly what it
is doing. Be interesting to see what if any refinements of current predictions
this model could lead to. Specifically if any insights are given for say the
cosmological constant driving the current cosmic acceleration.

~~~
d0mine
Abstract of the paper: No-Boundary Measure of the Universe
<http://link.aps.org/abstract/PRL/v100/e201301>

Another paper on the topic by the same authors: The Classical Universes of the
No-Boundary Quantum State <http://arxiv.org/abs/0803.1663v1>

