« first day (3265 days earlier)      last day (61 days later) » 

5:22 AM
Mood gorning biological organisms
 
5:34 AM
@NovaliumCompany Mood gorning sounds like a town in some third rate fantasy novel :-)
 
 
1 hour later…
6:58 AM
hey
 
7:46 AM
I just watched Synchronicity. Movie is nice but I feel like they didn't end it properly. I still don't have a clear explanation for the ending.
A question for dreamy beings: Do you think we'll ever be able to open up an artificial wormhole and travel through it?
 
@NovaliumCompany no
 
@JohnRennie optimism at it's finest
 
Wormholes (probably) require exotic matter and that (probably) doesn't exist.
 
I say, maybe the universe doesn't work the way we think it does. Maybe it's possible.
I feel like quantum mechanics is either too complicated for us to make proper sense of, or the universe is weird. (or maybe something else)
 
The thing is that QM works i.e. when we use it to predict the results of experiments we get the correct results.
You can suggest that there is some special case we haven't discovered yet where QM does something screwy ...
 
7:52 AM
Yep, that makes it even stranger. Something so counter-intuitive works. Why? Go figure...
I feel like there's something we're missing. Something that will explain this weirdness.
If someone thinks we have figured everything there is to figure in physics, go read some history.
 
@NovaliumCompany "I have no doubt that in reality the future will be vastly more surprising than anything I can imagine. Now my own suspicion is that the Universe is not only queerer than we suppose, but queerer than we can suppose." – J. B. S. Haldane
@NovaliumCompany Oh, we know that current physics has problems. Primarily, we don't know how to unify quantum physics with general relativity. Part of that problem is that most of the time you can ignore quantum physics when doing stuff that needs GR, and conversely, you can generally ignore GR (and indeed gravity) when doing quantum physics. You only need the combination in really extreme situations, and those situations are really hard (or downright impossible) to observe or reproduce in the lab.
 
8:12 AM
Random thought about omnipotence:
Trying to understand what happens when two omnipotents interact is very similar to how an entangled system behave wrt to an unentangled one
The analogy is as follows:
Recall that the major difference between an entangled state vs an unentangled state is that it has correlations that can exceed a certain bound prescribed by local hidden random variables
In QM, we have a model for the explanation of this phenomenon as superposition and hilbert spaces allows a richer algebraic structure that can allow such correlations, such as for some entangled state, you can have 1:3:3:1 for the outcomes of 00, 01, 10, 11
Now, in omnipotent interactions, we knew that because the two participants are omnipotent, it means regardless of what happens in that interaction, there is a resolution
thus they can produce something that is otherwise not possible in an non omninpotent system
However, unlike QM, because of the very nature of omnipotence necessarily violates classical or even modal logic, we do not have an explanation on how that resolution is made possible, other than the fact it is possible
Two interacting omnipotents also make me think of how many QFT interactions not in a strongly coupled system behave:
We usually start with fock states from infinity, and then they came together, interact in some unknown way, and then produce new fock states. We can then use these initial and final conditions to construct the S matrix that describe this interaction, even though we actually knew nothing in general what happens in the interaction regime
This is very similar to how when two omnipotents interact with each other, except we do not even have the luxury of producing a S matrix to model the interaction itself, it is fundementally incomprehensible
I guess, if at any time one felt stumped in QFT, go indulge in heaps of philosophy literature on omnipotence, and then you might just suddenly find the solution because compared to comprehending omnipotence, QFT is an easy piece of pie
 
8:30 AM
@Secret This concept may not be easy to digest for people raised in cultures dominated by Abrahamic faiths. In those faiths, there can only be a single omnipotent god. But it would be interesting to discuss it with someone from a polytheistic faith, like Hinduism. But even there, although Vishnu and Shiva may be considered omnipotent they never manifest their full potency outside their private abodes.
 
yeah, from what I read, it appears most omnipotent gods are often reluctant to display their full power and are humble. Meanwhile God in abrahamic religions is the one and only, thus God has no trouble of running into conflict with omnipotence
 
9:28 AM
Quick question: If the solar system were to be ejected from the galaxy, that wouldn't really change anything for life on Earth, right (assuming the Solar System isn't disrupted in any way)
The Galactic Habitable Zone is about star and planet formation from what I recall
 
Navigation by stars would certainly become more difficult :P
 
9:42 AM
But at least we'd get a lovely view of the Milky Way
 
-1
Q: Divergence of Discountinuous Electric Field

Ali Oz$E = E_{o}$ x < a E=0 x > a Now try to guess which charge distribution could give rise to this field without further calculation. Now use the equation ∇ · E = ρ/ϵo (which this time will require the derivative of a step function discontinuity) to figure out ρ

 
9:58 AM
@BetaDecay It could reduce the inner Solar system being bombarded by comets from the Oort cloud. But that probably depends on the exact mechanism that propelled the Solar system out of the galaxy.
@BetaDecay We can currently see the Magellanic Clouds, which are nearby dwarf galaxies. (At least, those of us in the southern hemisphere can). They aren't very bright to the naked eye.
 
@PM2Ring So in fact it may be beneficial to us? i.e. no more extinction-level events?
 
10:32 AM
@BetaDecay Potentially, yes. But I don't see any way to eject the Solar system from the Milky Way that doesn't cause all sorts of chaos.
 
Ah I see
I was considering the Andromeda-Milky Way merger
 
11:32 AM
123
 
12:23 PM
@BetaDecay Ok. That's in about 4.5 billion years, not long before the Sun expands into a red giant, causing plenty of chaos, especially in the inner Solar system. The Earth will be uninhabitable in about a billion years because the Sun is gradually getting hotter as it ages. On Earth, the temperature increase will cause a runaway greenhouse effect, and the ocean will boil away.
 
@PM2Ring Yes, but I wanted to know whether habitable life could survive an ejection
 
@BetaDecay I believe that it could, if the ejection happened slowly. But I don't know a way to make that happen naturally. With sufficiently advanced technology, I guess it's possible to move a star, and drag the planets & other system stuff along.
Stellar engines are a class of hypothetical megastructures which use a star's radiation to create usable energy. Some variants use this energy to produce thrust, and thus accelerate a star, and anything orbiting it, in a given direction. The creation of such a system would make its builders a Type-II civilization on the Kardashev scale. == Classes == There are three variant classes of this idea. === Class A (Shkadov thruster) === One of the simplest examples of stellar engine is the Shkadov thruster (named after Dr. Leonid Shkadov who first proposed it), or a Class A stellar engine. Suc...
 
 
3 hours later…
3:16 PM
If anyone is interested there is an interesting article about Atiyah on the AMS web site (12 page PDF). It mentions his interests in physics, though not in great detail.
 
@JohnRennie hi
There is an technical error in my phone can you help me
 
@yuvrajsingh what's the error?
 
Sir actually my phone sound and mic both stop suddenly, although I went to techcian he said both speaker and mic is OK, both nice, and speaker are currently working, after I switch on my phone, but after 5 to 10min a sound comes and voice stop @JohnRennie
 
Rennie the IT guy
 
@RyanUnger :-)
@yuvrajsingh does the sound stop for everything i.e. all the apps you try won't produce any sound?
 
3:31 PM
Nothing, sir even the keypad sound, voice everything drop @JohnRennie
 
Have you tried factory resetting it?
 
You mean deleting all data @JohnRennie
 
Yes. In the settings there is a factory reset option that completely wipes everything on the phone and returns it to the state it was in when it left the factory.
This is a last resort as you lose all data on the phone that isn't backed up somewhere, but it can fix stubborn problems.
 
I recently format my phone, but the issue is Same @JohnRennie
 
Are there any software updates available for the phone? What model phone is it?
 
3:35 PM
Yes phone says, me to update it version but I haven't, t done it yet, I have redmi note 3 @JohnRennie
 
It might be worth installing the latest update.
 
Finger cross, I am doing it, it take minutes only @JohnRennie
 
@yuvrajsingh good luck! :-)
 
I am going to buy a new laptop, can you suggest me @JohnRennie
 
@yuvrajsingh how much do you have to spend?
 
3:41 PM
You mean in euro or rs @JohnRennie
 
Either
 
maximum 60 thousand @JohnRennie
 
You should be able to get a great laptop for that sort of money.
 
Current I have hp @JohnRennie
 
3:46 PM
Look good, but I am not much sure about the brand @JohnRennie
 
Asus is a trustworthy brand. But I'm not specifically recommending that laptop - it was just the first I found on Flipkart.
Lenovo also have lots of good laptops in your price range.
 
You have apple I think @JohnRennie
 
The problem is likely to be that there are so many good laptops in your price range that you won't know which of them to choose.
 
True @JohnRennie
 
@yuvrajsingh I tend to use Dell computers because the company I used to work for uses them and I know Dell's range well. But I think Dell laptops tend to be expensive in India for some reason so they wouldn't be a great choice.
 
3:50 PM
@JohnRennie uh whats the conversion rate
 
I think hp and Dell have the same range, when I went to shop, 5 years ago, he shows me the Dell laptop first
 
The number one recommendation I have is to buy a laptop with a solid state disk - often called an SSD. These are more expensive than regular disks but they are so much faster than regular disks that they are worth the extra.
@RyanUnger last I looked it was about 85 rupees to the pound, and a pound is about $1.20.
 
hii @JohnRennie
 
But the Indian customs have steep tariffs on imports of computers so they are relatively more expensive in India.
 
Which one @JohnRennie
 
3:52 PM
@yuvrajsingh do you mean which laptop with an SSD ?
 
Yes @JohnRennie
 
All the manufacturers do laptops with SSDs. That Asus VivoBook I linked has a 512GB SSD.
@user8718165 hi :-)
@yuvrajsingh what I'm saying is, regardless of which manufacturer you prefer, Dell, HP, Lenovo, Asus, Acer, Samsung, etc, you should choose one of their models that has an SSD. It is the most important thing to have in a laptop.
 
Ok @JohnRennie I think I will download update tommorow only, if the problem what should I do.
 
@yuvrajsingh I would guess that there is a hardware fault in your phone, and that the update will make no difference. Sorry :-( But the update is worth trying just in case.
The update shouldn't delete any data, so it should be safe to install whenever you want.
Have you tried plugging in headphones to see if the sound works on headphones?
 
Right now, when I am talking to you phone sound is there, but I think it can go any time, no tried the headphone but there was no sound. @JohnRennie
 
4:00 PM
Hmm, no sound on the headphones either? Oh well, try the update and see if it works.
 
I think if doesn't, t work I am going to buy a new phone, @JohnRennie
With my b udget of laptop can be low @JohnRennie
Can you prefer @JohnRennie
 
You can get good phones surprisingly cheaply these days, though I don't know a lot about the phones available in India. The Chinese brands like Xiaomi and Huawei are probably the best value.
 
I think biggest festival of India Diwali is coming up, so there are so much of discount on products
 
How much would you spend on the phone? For example the Xiaomi Redmi Note 7S is around ₹10K and it's well regarded.
 
If I buy the laptop of 44 let say then 16 @JohnRennie
 
4:09 PM
I would guess you'd get a good phone for ₹16K
@yuvrajsingh there are some amazing Diwali deals on Flipkart! :-)
It's almost a shame I don't need a new phone :-)
 
Good night sir @JohnRennie
 
@yuvrajsingh bye :-)
 
4:44 PM
Why is Earth flat?
 
5:14 PM
@NovaliumCompany Because it isn't. Curvature is inversely proportional to radius, so if a sphere has a large radius then it has a small curvature, and it will appear flat when you look at it from up close.
 
5:37 PM
@PM2Ring The Earth is flat dude. The government is lying to us. NASA is trying to fool us.
I'm a proud member of the Flat Earthers Society.
 
hii :) @PM2Ring
 
If Earth is a sphere, then why are maps flat?
I'd suggest you learn some geography. Get a textbook but those which say Earth is a sphere or a geoid are fakes spread by the government.
 
 
1 hour later…
6:45 PM
@PM2Ring I can't tell when people are being srs about flat earth vs trolling
 
7:08 PM
Hello all. A GR question: It is known that in 2-d, any (regular) metric solves einstein's equations. Is it possible to construct an asymptotically flat metric, that is regular at the origin (take periodic euclidean time) but with the correct discontinuity, if we put a shell with arbitrary stress tensor on it? Would starting with and trying this for a constant stress tensor get somewhere?
 
7:57 PM
@Semiclassical Me neither. But I don't care, because I know that in either case any form of rational discussion is futile. OTOH, sometimes I'm tempted to engage in hyper-trolling: the Flat Earth movement was started by the government to reveal people who are gullible enough to believe in ludicrous conspiracy theories. And now that the government has that info, it can feed those people anything it wants.
 
8:47 PM
guys, what exactly do they mean by an exterior solution?
 
@ShaVuklia the part of the wavefunction that's outside the barrier
 
say we have V(x)=0 for 0<x<a, V(x)=C>0 for a<x<b, and $V(x)=\infty$ otherwise
@ACuriousMind yea, there lies my problem
given the potential I just gave
because we also have a vertical wall within the barrier
is griffiths still making a claim on such a finite vertical wall within the barrier?
because it seems that he is saying, as soon as we have vertical walls, we are free to patch together WKB solutions
while when the walls aren't vertical, we have to resort to a more elaborate patching technique
 
Yes, that's right. Where's the problem?
 
wait wait
so I didn't see why the WKB approximation doesn't break down, but I have to check the assumption
maybe that will clarify things
right, so the assumption in WKB is that the amplitude varies slowly
more precisely, $A''/A$ is very small compared to $(\phi')^2$ and $p^2/\hbar^2$
so my question is
how does it follow from this that at a vertical wall, WKB doesn't break down?
oh hm
I think I kind of intuitively see it
in the case of a tilted potential, you can say that WKB breaks down in the vicinity of the turning point
so the whole WKB solution near the vicinity doesn't make sense
while in the case of a vertical wall (finite or not), we know that WKB holds arbitrarily close to the turning point
so there is no point in patching solutions in vicinities of the wall. all we have to do is patch them together at the exact turning point
okay sry, this was actually a bit easier than I expected
but I felt extremely confused for a second
 
9:14 PM
okay, so final question: What we want is that $A''/A$ is much smaller than $(\phi')^2-p^2/\hbar^2$ for WKB to work. In the vicinity of a turning point (which is not a vertical wall), we have $p(x)=\sqrt{2m(E-V(x))}\approx 0$, so obviously $A''/A$ can't be much smaller than $p^2/\hbar^2$.
However, what if $(\phi')^2$ is still relatively large? It seems that WKB would still hold then. So I'm guessing my question is how $\phi'$ relates to the potential (or the difference between $V(x)$ and $E$), and if we are safe to assume that $\phi'$ will also be relatively small at a turning point?
 
 
1 hour later…
10:15 PM
@skullpetrol I think this tag will become increasingly plausible if SE keeps making posts like this
 
 
1 hour later…
11:30 PM
@PM2Ring I will be free in maybe less than an hour from now. If you can talk to me about what we were talking about a while ago in about an hour or less from now please let me know. I really want to continue our conversation. If you can't talk in an hour or less from now also let me know. I'm terribly sorry for all of the interruptions stopping us from being able to talk.
 

« first day (3265 days earlier)      last day (61 days later) »