« first day (2090 days earlier)
← previous day
next day →
last day (2839 days later) »
00:00 - 17:00
17:00 - 20:00
20:00 - 23:00
ACuriousMind
8:02 PM
I'm proud of you!
Bernard Meurer
It did require asking DS & a friend for help
my friend walked me through the phone and, most importantly, made me give up on trying to flip the egg like a chef with just one hand on the pan
ACuriousMind
...what exactly about "crack open egg, put into ban, stop before it's burnt" did require
two
people to assist you? :D
Bernard Meurer
@ACuriousMind
It's not that simple
ACuriousMind
lol, just don't try flipping stuff like that
yuggib
@Slereah I hath not...
the free vacuum in the wavefunctional rep is just $1$
(seen as a constant functional, square integrable wrt the gaussian measure)
Bernard Meurer
8:10 PM
@ACuriousMind Why is there no [magic] tag for questions?
Slereah
@yuggib Well 1 up to a phase, yes
yuggib
the ladder operators I don't know exactly...probably they are derived by linear combination from the fields
@Slereah no no, just one
Bernard Meurer
@ACuriousMind
please edit kthxkss
Slereah
Why no phase?
Aren't all wavefunctions defined up to a phase
ACuriousMind
@BernardMeurer [There is].
Slereah
8:12 PM
So the normalization is just $\int d\mu(\varphi) = 1$, right?
yuggib
not really...they are the square integrable functions wrt the gaussian measure
Slereah
With $\mu$ the Gaussian measure
yuggib
exactly
Slereah
Hm
So $\langle 0 | \varphi | 0 \rangle = \int \varphi d\mu = 0$ makes enough sense, I guess?
It's the mean of the gaussian measure
yuggib
yes, that's it
Slereah
8:15 PM
I have this Feeling that maybe $a^\dagger_k \approx \varphi_k$, with $\varphi_k$ the one particle wavefunction
And I guess maybe $a_k = \frac{\delta}{\delta \varphi_k}$, if that makes sense?
ACuriousMind
@BernardMeurer I have nothing to edit there
Bernard Meurer
@ACuriousMind I'm glad :)
yuggib
@Slereah not exactly
the field is the multiplication by the variable, and the momentum is the derivation plus the variable
Slereah
Yes, but isn't that what we are supposed to get
yuggib
yes, more or less
Slereah
8:18 PM
$\hat a^\dagger_k | 0 \rangle = a^\dagger_k 1 = \varphi_k(x)$
Although...
I suppose the two operators wouldn't be complex conjugates then
Hm
yuggib
the cre ann ops can be derived by the. field and momentum by linearity
Slereah
yeah
Something like $$a_k(x) = \frac{1}{\sqrt{(2\pi)^n 2 \omega_k}} \int d^n x e^{ikx} (\omega_k \varphi(x) + \frac{\delta}{\delta \varphi(x)} - \varphi(x))$$
Not quite sure how to simplify it, though
yuggib
well, something like that
but maybe there is a more explicit form somewhere in the literature
Slereah
probably
I tried looking up Rovelli but then again it has $\pi = \frac{\delta}{\delta \varphi}$
Might not be too exact
Also is $\pi = -i(\frac{\delta}{\delta \varphi} - \varphi)$?
Seems a bit weird, unit-wise
yuggib
yeah it's something like that
Slereah
8:29 PM
It ends up giving a term like $\varphi (\omega_k - 1)$ for $a$
0celo7
@BernardMeurer Uh, do you not know what he looks like?
@ACuriousMind ...what
image of
what
ACuriousMind
Image of
the point
0celo7
under?
Bernard Meurer
@0celo7 ACM you mean?
0celo7
yes
Bernard Meurer
8:35 PM
@0celo7 I know how he looks. Even tried adding him on facebook but he said he hated me and wished I was dead :(
0celo7
savage
ACuriousMind
That may or may not be an accurate representation of events
0celo7
@ACuriousMind I still don't get what "fiber preserving" means
Bernard Meurer
@ACuriousMind We'll see about that in court
0celo7
I'm bad at algebra
Bernard Meurer
8:39 PM
I'm the victim, you can't disagree with me. Stop victim shaming
0celo7
@ACuriousMind Argh, what the heck does fiber preserving mean :/
ACuriousMind
I don't know what your problem is
0celo7
Everyone says it maps fibers into fibers or something
Which fiber gets mapped into which fiber?
ACuriousMind
$f(E_x)\subset E'_{\pi(f(x))} = E'_x$.
0celo7
Aha, that's my issue
What is $f(x)$
what the heck
what is $\pi(f(x))$
What is $x$?
ACuriousMind
8:46 PM
A point in the base.
0celo7
$f$ is defined on $E$, not the base.
Assuming $f:E_1\to E_2$
ACuriousMind
Okay, yeah
Fiber preserving just means $f(E_x)\subset E'_x$.
0celo7
???
What if the bases are different
And what is $E'_x$
ACuriousMind
Then it means that the diagram on that Wiki pages commutes
Bernard Meurer
lol
ACuriousMind
8:48 PM
@0celo7 I'm calling the bundles E and E' because I don't want to type double indices
0celo7
@ACuriousMind oh
@ACuriousMind which one
ACuriousMind
@0celo7 ...there is only one that applies for the case where the bases are different.
The fiber-preserving aspect in that case is that if one point of $E_x$ lands in $E'_y$, then already $f(E_x)\subset E'_y$.
0celo7
How do you define the map between the bases
ACuriousMind
You don't
0celo7
Wiki's $f$ IIRC
ACuriousMind
8:51 PM
It is a requirement that it exists.
But you can recover it from $f(E_x)\subset E'_y$ in an obvious way.
0celo7
@ACuriousMind ...
how
I'm not doing too hot today
ACuriousMind
No, I'm not writing that down
0celo7
9:09 PM
@ACuriousMind do you just project the mapped fiber onto the second base
ACuriousMind
yes
0celo7
@ACuriousMind I would ask why you didn't write that but you'd get annoyed
Chinatsu-creepy-chan
9:36 PM
Hello, good evening. Can someone please help me with mathematical explanation of a physical concept?
1 hour later…
0celo7
10:48 PM
@ACuriousMind what is the tensor product of matrices?
00:00 - 17:00
17:00 - 20:00
20:00 - 23:00
« first day (2090 days earlier)
← previous day
next day →
last day (2839 days later) »
all rooms
Transcript for
Jul
24
Jul '16
25
Jul
26
The h Bar
General chat for Physics SE (
physics.stackexchange.com
). For M...
7
15
join this room
about this room
00:00
06:00
12:00
18:00
all times are UTC
site design / logo © 2024 Stack Exchange Inc;
legal
mobile