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3:42 AM
In QM, in the double slit experiment, will the wave function collapse if we put a detector, the detector detects, but when make sure the information is deleted?
What if we use an animal?
Despite all attempts to trick the system, eventually we always get to the human observation? (or potential to do so?)
 
4:33 AM
@NovaliumCompany The problem isn't that the universe doesn't want you knowing about the particle. It's that any method to learn about the particle will interact with it, and therefore alter it in some way
Try to see it? The light particle interacted with it.
In the end there's no way to learn about it's "undisturbed state" without disturbing it, which results in the wavefunction collapse
 
 
3 hours later…
7:42 AM
0
Q: Erasing comments for questionable reasons

ExocytosisThe following relates to this answer written by Emilio Pisanty: Is there a magnetic attraction between two parallel electron beams? Originally, the said answer was referring to a chapter that did not exist in the most recent edition (3rd) of the book. Naturally, I commented about it, asking for...

 
 
1 hour later…
8:50 AM
A delayed-choice quantum eraser experiment, first performed by Yoon-Ho Kim, R. Yu, S. P. Kulik, Y. H. Shih and Marlan O. Scully, and reported in early 1999, is an elaboration on the quantum eraser experiment that incorporates concepts considered in Wheeler's delayed-choice experiment. The experiment was designed to investigate peculiar consequences of the well-known double-slit experiment in quantum mechanics, as well as the consequences of quantum entanglement. The delayed-choice quantum eraser experiment investigates a paradox. If a photon manifests itself as though it had come by a single path...
 
9:03 AM
0
Q: Should we flag all comments that are no longer needed?

ExocytosisParent question: Erasing comments for questionable reasons I am trying to get a general policy. My initial concern was about comments to answers that asked for details and/or corrections, and were erased as soon as the answer was updated accordingly. There are numerous comments all over SE that...

 
 
1 hour later…
10:23 AM
Heyyyy
I looked up my emails for my site
It's John Manchak!
I need to add some captcha on my site's message form because there are way too many spams
"Hey Slereah, don't you allow comments on your blog? I do on my blog:

http://physicsdetective.com/

I wanted to leave you a comment pointing out that there's no travelling around a closed timelike curve. Wheeler conflated a circle with a cycle. Spacetime models space at all times. It's an abstract thing, not something real. The map is not the territory.

Regards
John Duffield"
DUFFIEEEEELD
 
10:43 AM
Oh god
Duffield sent me several messages
"LOL, that h-bar is a laugh. I was born 13 months after Einstein died."
 
Jim
11:43 AM
@Slereah Is he trying to imply that he is Einstein reincarnated?
 
It is certainly suspiscious
 
Jim
Obviously Whoopi Goldberg is Einstein reincarnated. So he can't be
That's why she was always center square on hollywood squares. She was that smart
 
12:10 PM
I was originally not going to post this, but seeing the JD message make me facepalm so much that I decided to just unleash a logic bomb to h bar
Meanwhile, in a double irony, I think I started to have some idea what time travel in presentism will be like
All that is needed is two spacelike events to be classically correlated, and then the memory of the observer encodes that event in such a way so that when reading out the history recorded by the person, you recover a structure of events that arranged like a CTC
 
12:45 PM
:52170414 The message form on my website
 
"Wheeler conflated a circle with a cycle."
What does he mean by this
Also Wheeler was a professor here
There's a big picture of him in the physics department
 
Jim
@RyanUnger I'm more curious what he means by "The map is not the territory". I get that I don't walk on the map to get to my destination, but if there's a trail on the map I expect to be able to walk on that trail
 
Wheeler is kind of a weird GR figure
He seems to be super huge in GR but I can't think of that many things attributed to him?
 
Jim
all figures in GR are weird
 
@Jim I think he means local coordinates are not the whole manifold...
 
12:49 PM
Not wrong
 
But does he actually know what a manifold is
 
I'm not sure Duffield actually means something when he says such things
 
Jim
Next thing you know, he'll be pushing the time cube idea on all of us
 
time cube?
 
12:53 PM
Harmonic Cube
oh no
 
Jim
do yourself a favour and don't read the whole thing. Scroll to a random place and read a line or something
 
scrolls
oh jesus
(Dr Gene Ray, Cubic and Wisest Human, depicted in image above)
there's a wikipedia page
@Jim actually
 
Jim
"Religious/academic taught singularity is unicorn as 1 burrito"
 
Duffield just means that our understanding of physics is precisely that
it's not a perfect description of reality
I think Duffield says lots of reasonable things
They just dont fit together too well
 
Jim
@RyanUnger I think we're aware of that. But I don't get how that makes travel around CTCs impossible
 
12:57 PM
because CTCs are an artifact of the theory, not a part of reality
 
Jim
we may not live in a spacetime with them, but I fail to see how they'd be untraversable were we in the proper spacetime
 
does jd believe in quantum mechanics?
maybe he's thinking of some kind of instability mechanism
 
It is hard to say what JD believes
it is not greatly coherent
 
Jim
probably yes, but I don't want to speak for him
 
too bad the mods keep banning him from here
 
1:00 PM
Well I mean
He has a website
if you want to talk to him you can go there
 
Jim
@RyanUnger really? I didn't notice that. CTCs make great toy models for a variety of things in GR
 
Also since you are only interested in math I'm not sure the whole wormhole/CTC issue is greatly relevent
 
lol well one of them comes to se so ill retract that
 
It's just a manifold that isn't simply connected
 
but its true to some extent
 
1:01 PM
Well it's not a super useful field of GR, certainly
As far as experiments go
 
the real issues in GR are not due to topology
 
But overall most of GR isn't super useful
 
Jim
^ that
 
no one is claiming to do useful work
2
 
You could probably do most of the experimental GR work with linearized gravity
 
Jim
1:03 PM
@RyanUnger That should be the physicists creed
 
or parametrized post newtonian formalism
 
non sequitor rant: university tells me my password has expired, fine
but now apparently your university password has to be 16 characters long
and...srsly?
 
such is the modern world
just use a password manager
or write it on your phone
 
1:21 PM
@Semiclassical At work, there's a system where you have to change the password when it expires. When you go to change it, there are two boxes "Old Password" and "New Password"; there is no "New Password (repeated)" or similar box to fill in. When you enter an old and new password, it just spits up the error "the passwords do not match"... even though the old and new password aren't supposed to match
Its kinda a crappy old system so IT seems happy to just reset the PW for me when it expires
 
1:33 PM
@Semiclassical well, be thankful that you're not in UCL
they have an entropy meter that determines how long your password will be valid for
 
heh
I work in the PRIVATE SECTOR and they are super big on security???
@EmilioPisanty cf above
The company's website just assigns new passwords to you periodically
 
@Slereah ugh
 
Jim
mandatory xkcd reference:
 
Now that Manchak said he likes my article on non-Hausdorff manifolds I guess I have to finish it
 
Jim
@Slereah How dare he be interested in what you did! Honestly, some people don't take the time to consider other people's schedules when they just go around liking physics works.
 
1:52 PM
It is very much appreciated, but now I am embarrassed by how terribly unfinished it is!
 
2:45 PM
@Jim but if everyone used random collections of words, it'd be much easier to crack
 
Jim
@RyanUnger different languages?
 
 
1 hour later…
4:13 PM
@RyanUnger There are about 59 million words in the English OED. If everyone uses a random collection of 4 words, the search space is 59 million to the power of 4, which is larger than 2^103, so that's still much better than a short gibberish password
 
@ACuriousMind i don't think your average individual knows 59 million words
 
If we pessimistically reduce that to the average passive vocabulary of English speakers of 40000 words, we still get about 2^61
If the attacker is only going for low hanging fruit and only checks for the 1000 most common words, we're still at 2^39
I.e. the computation Randall makes there already accounts for the "passwords are only made of words" attacks, since his 2^44 isn't far off from this
 
4:31 PM
so is there any point to changing passwords every 3 months
because my uni requires that and it is starting to seem very stupid
 
@SirCumference Well sure
But it also has downsides
honestly when there are a lot of password changes and the passwords have to be very complicated, I just use a lot of "I have forgotten my passwords"
 
@Slereah i mean presumably it's in case my password was cracked already, so that it wouldn't work anymore
but if it were cracked already i'd probably see some red flags
and if it weren't cracked then there's no benefit to changing my password frequently
 
I just use the Spaceballs password
 
Take a computer that runs infinitely long time
and make a 0 to 1 at the current tape position if the input have a maximum
It turns out it is extremely hard to tell whether the input is finite without referencing the natural numbers
(at least philosophically that is, I don't know how you compute on infinitely non stopping turing machines)
 
@Slereah : The pointy-haired boss in one Dilbert strip uses 5 asterisks * * * * * as password inspired by how the password box looks like before typing :D
 
To be fair, hard to guess!
But easy to crack
 
5:20 PM
@Slereah well, it appears 27k times in Pwned Passwords, so I wouldn't consider it really safe
 
Apparently fartbum is also unsuitable
"This password has been seen 42 times before"
monkeylove has been used 4332 times
Damn
It's hard to find an appropriate random combination of words
correcthorsebatterystaple has been used 120 times
showmethemoney 3,393 times
where'sthebeef is available, though
if you need a new password
 
5:52 PM
RicciFlow is good
@ACuriousMind 59 million?
I know at most 2000 words
 
@RyanUnger Then you would sound like this:
 
6:08 PM
I only know one word
So I use this instead
 
6:40 PM
@Loong what is this
 
I said 2000
I think that’s about right
 
 
3 hours later…
10:07 PM
 
hmmm
So the idea would be to stay in the age before science?
 
10:35 PM
@Slereah How'd ya respond
 
I did not
 
11:03 PM
To me that reads like total satire, but I would sadly believe if it's not.
 

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