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12:05 AM
@ACuriousMind yes! it is rather flamboyant today!
 
I've received an unusual cluster of unexplained downvotes recently. One per site on five different sites in the last three days. I wonder if it is just coincidence or if someone thinks they can grief me with so underwhelming an attack?
 
12:23 AM
@ACuriousMind Exercise: Show that there is no such rational $r$ that satisfies $2^r=3$. My solution: Write $r=p/q$ with $p,q$ integers. Suppose there were such an $r$. Raise both sides of $2^{p/q}=3$ to the $q$-th power. We obtain $$\frac{2^p}{3^q}=1$$
However, this is a contradiction because the numerator and denominator do not share any factors. Hence, there is no such $r$.
 
@dmckee Five downvotes in three days all on different sites? Your standards for an attack are certainly low
@0celo7 That looks fine to me :)
 
@ACuriousMind That was exercise #2.
I don't like analysis.
@dmckee The greatest attacks start slow.
 
Can't say I particularly like it, either :P
 
I have to do homework...ain't got no time for more
lol...I'm so used to GR/SR I used the perpendicular projector for a Lorentz signature metric on my LA homework
 
12:49 AM
@ACuriousMind The damage isn't worth mentioning, and I'd been assuming it was a coincidence. It's just that 0/5 is an unusually low number of comments if this was just the usual diversity of opinion on the internet. In any case, the trickle of votes I get from old questions on site where I don't participate much is more than enough to cancel them out.
But, it would be more baffling if it was an attack, explicitly because it would be totally lost in the noise.
 
Well, apparently it is not lost in the noise, because you're now wondering about where this signal came from ;)
 
 
1 hour later…
2:14 AM
Animals have been submitted as applicants to suspected diploma mills and, on occasion, admitted and granted a degree, as reported in news and magazines. Animals are often used as a device to clearly demonstrate the lax standards of awarding institutions. In one case, a cat's degree helped lead to a successful fraud prosecution against the institution which issued it. == CatsEdit == === Colby NolanEdit === Colby Nolan is a housecat who was awarded an MBA in 2004 by Trinity Southern University, a Dallas-based diploma mill, sparking a fraud lawsuit by the Pennsylvania attorney general's of...
why is that tab open
how did I get there
 
obe
7 hours ago, by Slereah
Animals have been submitted as applicants to suspected diploma mills and, on occasion, admitted and granted a degree, as reported in news and magazines. Animals are often used as a device to clearly demonstrate the lax standards of awarding institutions. In one case, a cat's degree helped lead to a successful fraud prosecution against the institution which issued it. == CatsEdit == === Colby NolanEdit === Colby Nolan is a housecat who was awarded an MBA in 2004 by Trinity Southern University, a Dallas-based diploma mill, sparking a fraud lawsuit by the Pennsylvania attorney general's of...
You clicked it because you were curious.
 
I see
Interesting
The things I do subconsciously
@obe any QM/GR concerns?
I'm typing a psychology thingie, but I can help you if have questions
 
obe
2:30 AM
@0celo7 Too tired to think. Though I don't really remember having any concerns yet.
I'm on ch11 now.
 
TFW you do a long calculation starting from some assumption
and just end up rederiving the assumption
 
if you're too tired to think, you're too tired to read
god damn you Weinberg
I need to learn renormalization but I don't know how
 
obe
@0celo7 True though I didn't say I was reading.
 
and Weinberg is just confusing me
 
I like Srednicki best for that
renormalization that is
 
2:31 AM
but I don't want to read a whole book
and his sections are crazy spread out
 
obe
@0celo7 Have you tried this book?
 
no
my poor reading list...
I have this algebraic topology book that I need to read
tomorrow I should return de Felice/Clark and Carothers to the library
the former might be overdue actually
at this rate I'll never get to the algebraic geometric twistor formulation of quantum field theory
is "string computing" a thing?
like the motherboard is a D-brane and you have stringy transistors or something
like quantum computing inside a black hole
 
How many books are on your reading list that are assigned?
@0celo7
 
I have...at least 5
and $\lim_{n\to\infty}(n-5)$ not assigned
 
LOL
love it
 
2:51 AM
Can anyone here answer a question about Josephson junctions?
 
Sigh
Girl stays over, forgot her asthma medicine, starts having breathing problems around 2 AM, neither of us slept all night. Bad times :\
 
Wowowow!
Been there
That sux dude
:(
@Danu Is she okay?
 
there is string communication
 
It's now 5 and she's on the earliest train home
 
user image
2
 
2:57 AM
@Slereah lol
 
@StanShunpike Relatively speaking, I guess
 
That stuff can be really serious
 
A tin can telephone is a type of acoustic (non-electrical) speech-transmitting device made up of two tin cans, paper cups or similarly shaped items attached to either end of a taut string or wire. It is a form of mechanical telephony, where sound is converted into and then conveyed by vibrations along a liquid or solid medium, and then reconverted back to sound. == History == Before the invention of the electromagnetic telephone, there were mechanical acoustic devices for transmitting spoken words and music over a distance greater than that of normal speech. The very earliest mechanical telephones...
damn
"Their maximum range was very limited, but hundreds of technical innovations (resulting in about 300 patents) increased their range to approximately a half mile (800 m) or more under ideal conditions."
I want a fucking tincan phone with that range
 
> I always thought of Skorokhod associated with the topology for convergence in the space of càdlàg (right continuous with left limits) functions in probability.
 
get your ads outta here
don't make me call the mods
 
3:01 AM
yay first jazz band meeting tomorrow
life has meaning again
 
@0celo7 lel
 
@FenderLesPaul What instrument do you play?
 
@StanShunpike guitar
 
@FenderLesPaul That's awesome! I was thinking of learning to play. I write tons of music. I wrote a guitar concerto and a guitar trio.
I also write a lot of electric guitar pieces
 
@Danu Did you see my answer to your question?
 
3:07 AM
@StanShunpike that's pretty sweet dude
definitely learn to play
guitar is such an insanely versatile instrument
 
@FenderLesPaul It is. Even Vivaldi has some pieces for it I think.
It's kinda confusing cuz ppl adapt old songs to new instruments, but he definitely has some pieces that play reallly well on it
There is also such a variety of guitars
It's mindblowing how into it ppl get
 
yeah
I stick mostly to jazz, blues, and pop/folk
but the library for guitar is vast
scarily so
 
What kind of jazz artists are you into?
I listen to gillespie, Coltrane, Davis, Armstrong, Ellington, art pepper
Charles Mingus
 
Lee Ritenour
Pat Martino
Wes Montgomery
come to mind
Miles Davis
Django Reinhardt if you go back far enough '
although I can't fingerpick as well as him
I really want to improve my technical playing skills
but that takes a lot of practice everyday
and physics research really gets in the way of that
plus I have to work on singing at the same time so I can never seem to get to the level of finesse on guitar that I want :(
 
That is a lot to master indeed
@FenderLesPaul do you do recordings too or just play?
 
3:18 AM
like personal recordings? I haven't yet no
don't really have the correct equipment for that
I tried using garage band on my laptop
but it records the guitar in a very weird way
it seems to lose all the reverb
 
Yeah recording takes equipment to sound right
Synthesizers dont have that issue but they also never come close to sounding real
 
3:35 AM
yeah
like here's a quick example
it's very short
the software makes the guitar sound really flat
 
4:15 AM
@0celo7 Yessssss. It's sad that working on any one book takes time away from everything else.
 
5:18 AM
@FenderLesPaul So what are your top three favorite jazz songs? give me 6 in total. Favorites to listen to and then favorites to play.
@NeuroFuzzy what have you been doing this summer?
 
 
2 hours later…
7:42 AM
@DanielSank is your avatar related to this :P
 
8:31 AM
@Rigor Heh, not in particular.
I just really like octopuses a lot.
They're awesome!
@FenderLesPaul Django was a boss.
 
9:13 AM
@Secret I did
 
9:32 AM
I see... yeah, that's a LONG list
 
10:07 AM
0
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10:49 AM
@Slereah Neat-o.
 
looks really spammy, a bot?
 
11:12 AM
@Secret Yup.
 
11:52 AM
obviously it's a question about newtonian gravity
It's right in the tags
 
no it isn't, it's a question about a home-experiment :P
 
me: energy is not conserved in GR
JD: I haven't seen a perpetual motion machine, and neither have you
@Slereah he got me
I have not seen a perpetual motion machine
 
Well perpetual motion machines are about the second law of thermodynamics, not the first
Entropy still goes up in GR
 
Eh, I meant "infinite energy machine"
 
I wonder if there's any non-black hole formula for the entropy of the gravitational field
 
12:06 PM
@Slereah there's your research topic
 
Well the FRW spacetime totally has infinite energy
Well infinitely negative, but still
Since lambda dominated terms just make the dark energy increase indefinately
Not sure if you could get infinite positive energy though
I suspect that with backreaction, that wouldn't happen
 
So is JD saying GR is...wrong D:
But Einstein and the evidence
 
12:39 PM
@StanShunpike Eh, not as much as I'd like to! But I have got a lot done on this Manifolds Tensors and Forms book. Right now I'm aiming for 10hrs/day of reading/coding, but I'm struggling to hit that mark. Mmostly because I occasionally get sucked into the internet :p
 
Well
Duffield has no background in either math or physics
it's pretty hard to explain much in the ways of GR to him
 
as he demonstrated with his inability to explain division by 0
 
12:56 PM
Well 0 is excluded from division over the reals by definition
⊢ / = (x ∈ ℂ, y ∈ (ℂ ∖ {0}) ↦ (℩ z ∈ ℂ(y · z) = x))
 
all he did was just provide a link to the wiki page
 
that is his go to move
Link to pop science sources
 
true
 
if you want a fun definition of Hilbert spaces, btw : us.metamath.org/mpegif/mmtheorems169.html#mm16886s
⊢ ⇝v = { [<.] f, w [>.] ∣ ((f:ℕ–→ ℋ ∧ w ∈ ℋ ) ∧ ∀x ∈ ℝ+ ∃y ∈ ℕ ∀z ∈ (ℤ≥ ‘y)(normh ‘((f ‘z) −h w)) < x)}
help
 
1:14 PM
@0celo7 : energy is conserved full stop. The people who tell you energy is not conserved in GR are making airy-fairy handwaving assertions. They can't explain where this magic free energy comes from. But I can explain how energy is conserved when a brick falls down.
@skillpatrol no I didn't. I explained it perfectly adequately.
 
@JohnDuffield How so?
please explain it right here and now @JohnDuffield
no links
 
@skillpatrol : division tells you how many times you need to add a value to get to another value. For example you add 2 and 2 and 2 to get 6. So 6 divided by 3 is 2. Only you can't add 0 to 0 any number of times to get 6. Because division by zero is undefined. It isn't infinite, because you can add 0 to 0 to 0 an infinite number fo times, and you still haven't got 6.
Doubtless in a day or two skill patrol will say I didn't explain it at all.
 
@JohnDuffield You don't know Noether's theorem, do you?
 
@ACuriousMind : yes I do.
 
Then how can you assert energy is conserved in a theory which is not time-translation invariant?
 
1:22 PM
But I don't know of any perpetual motion machines.
@ACuriousMind : because energy is real. Matter is made of it. You might think the blue-shifted photon gained energy, but it didn't. Instead you lost it.
 
@JohnDuffield ...because every machine we know operates on scales at which the universe is well described by special relativity, or at least spacetimes with a time-like Killing vector, such that there is energy conserved. Cosmology operates on scales where there is no guarantee that there universe is well described by such a spacetime, hence energy need not be conserved.
@JohnDuffield Then you have not understood Noether's theorem. Which symmetry is associated to this energy conservation you assert?
 
Nor have you understood the definition of division.
In the set of real numbers.
:-)
 
@Slereah Really there is no need of such verboseness as this site uses...I love rigorous statements in mathematical language, but sometimes abbreviations and words are not a crime.
 
@JohnDuffield I think you're confusing global vs. local notions. Locally, energy is conserved (this is hard-wired into the Einstein field equations), but globally it's not even possible to really properly define a notion of energy in general.
In some sense, this is equivalent to the statement that it is not conserved (we wouldn't want to call it energy without any caveats otherwise)
Now, you may insist that a global notion of energy is pretty useless, and maybe it isn't all too important in practice. But it's important, at least for fully rigorously understanding the nature of the objects we're studying.
 
@ACuriousMind : that's just a handwaving assertion. I understand Noether's theorem, and moreover I understand energy. And time, and time invariance. Note that matter is made of energy. Energy is not some abstract thing like a law of physics. Also note that saying energy conservation is there because of a time-invariance symmetry is just a tautology.
 
1:36 PM
> Also note that saying energy conservation is there because of a time-invariance symmetry is just a tautology.
how can you even assert that it is conserved in non-time translation invariant spacetimes, then
 
Phew, good thing he didn't find out about Unruh radiation
God knows what would happen then
 
@Slereah Stop the childish "behind-the-back talk".
 
::gets popcorn::
 
^not letting this happen again.
 
I'm in the nukeE lounge
No popcorn for miles
 
1:38 PM
@Danu : I'm not confused in the slightest. Really. See how you referred to spacetimes? Spacetime is an abstract thing. Energy isn't. Nor is space, or motion. These things are modelled using spacetime, but the map is not the territory. Einstein never confused spacetime with space.
 
Although there is a microwave
 
@Slereah If you have a point to make, at least have the decency to have a serious discussion with the people you don't agree with about those points.
 
What would be the point
 
@Slereah If you don't see one, then don't get mixed up in the discussion.
It's not that hard.
 
@JohnDuffield ffs, I mixed that up (read: misread) once...let it go!
 
1:39 PM
@Slereah have some popcorn pal
 
@JohnDuffield Spacetime is not more or less abstract than space itself. In fact, you cannot separate out time at all, as you should be well-aware of.
> but the map is not the territory
what does that mean?
 
@0celo7 : I wasn't referring to you. A lot of authors don't know the difference between space and spacetime, even people who you would think of as authoritative.
 
Which ones specifically?
Books and pages please.
We need evidence of your claims.
@Danu anarchist political commentary, methinks
 
@0celo7 LOL!
 
@Danu : Danu, that's wrong I'm afraid. Space is the gin-clear ghostly elastic continuum around surrounding the Earth. Spacetime is an abstract mathematical space which models space at all times. As a result there is no motion in spacetime. It's the block universe. You can draw a worldline in it, but you aren't moving up that worldline. I say this as a "relativist".
 
1:44 PM
Gin-clear? What kind of gin do you drink?
I am partial towards Tanqueray and Bombay Sapphire.
 
@JohnDuffield ...your interpretational issues (because that's all they are) with motion and the special role you ascribe to space will not help you establish conservation of energy
@0celo7 Way too mainstream ;) Can't be any good
(going on my experience with whisky)
 
@Danu You're telling me Jameson is no good?
 
@0celo7 Not once you taste the good stuff, it ain't. Sadly! I used to like that stuff a lot before I got more into whisky
 
@0celo7 : Wheeler, who talked about matter curving space, and even this. It's space around the Earth, not spacetime.
 
@JohnDuffield Wheeler is really old, I don't have any of his books.
Try again.
 
1:46 PM
you should get MTW
It's intersting
if a bit messy
 
I do not need a 1,100 page book on my list dammit
I need like -10,000 pages
 
Well reaaaad
what are you reading right now
 
School stuff
 
@Danu : I have no interpretational issues. And if you can show me an example of non-conservation of energy, I'm all ears. In fact I'll ask a question about that. But not now. Work calls. I have to go.
 
@JohnDuffield Example: cosmology
We need to have a JD vs. Lumo debate
 
1:48 PM
@0celo7 : handwaving assertion. Now I really must go.
@0celo7 : and lost. We've crossed swords before. He won't take me on. Not about GR or electromagnetism or fundamental physics.
 
haha
oh that's rich
he took on Harvard
 
@0celo7 : and lost.
 
lol you beat Lumo
show of hands who believes that
 
Gotta go. Bye for now.
 
Later pal.
 
1:54 PM
@skillpatrol I need to buy some popcorn.
 

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