where postulate iii) reads "immediate repetition of a measurement yields the same outcome". what does this have to do with creating copies of a state?
hm i guess the measurement device is taken to be a copying machine?
but i don't really understand why the idealized measurement device should be represented by a state that is exactly the state of what you are trying to measure
It is really difficult to discern what such snippets are intended to mean without the surrounding context. You really should learn to take better pictures, so that we can tell whether the surrounding context are useless at explaining what the author meant.
@nickbros123 mhh, the rare times that I write an answer, I tend to make calculations directly from my mind to MathJax. If things get bad I have to use a pen :P
i only answer questions that do not involve explicit calculations or that i have computed in the past and recall the result and how to get there :P
a number of people ask "soft proof questions" in which case it is usually easy to mentally work through the "soft proof" or build off of existing answers to other stack questions
does anyone have a precise way of describing decoherence and its relation to einselection? I am having trouble understanding Zurek and Schlosshauer seems to oversimplify and do something quite different than Zurek.
Because in one paper Zurek makes it out that Einselection solves the preferred basis problem which then paves the way for decoherence
my understanding currently: 1) you start with the notion of a von Neumann (pre-)measurement. This is the mechanism by which a measuring apparatus becomes entangled with a system and by which the environment becomes entangled with the aparatus-system composite.
2) You suppose that realistically, only the system is available for measurement. This means that taking the partial trace over all degrees of freedom but the system is theoretically the right thing to do to obtain the object containing all the information accessible to you, a local observer.
* oops it seems you only trace out the environment
3) the resulting reduced density matrix will have some which-state dependencies (depending on how much "information is encoded in the environment"). The change with respect to time of these terms is essentially decoherence.
Maybe take that there are some re-measurement that is really just taking the experimental record and making a new copy. Then, by no-cloning theorem (note that this is not just quantum, there is a classical one too), you cannot clone a quantum superposition, only simple pointer states.
The paragraph right before is needed to help understand what he is saying.
If u deny this then must deny that zero was being discovered in Europe or arabs
In 772 an Indian astronomer travelled to the court at Baghdad and introduced Brahma-sphuta-siddhanta of Brahmagupta(written around 628 CE) The caliph Al-Mansur charged Al-Fazari with its translation, the book was known as As-Sindhind al-Kabir
The great Persian scholar Al-Khwarizmi(780-850) wrote a book on astronomy borrowing from various sources. The Indian sources were Brahmasidhanta and the much older Suryasidhanta(written in late 4th century).
@JackRod I'm not sure how what you're saying is a response to what I said: I'm not denying that there is a long tradition of mathematics in India or that Indian mathematicians were in contact with the rest of the world at several points in time
I'm saying the specific claims in that video are largely wrong, for instance "the concept of pi" did not spread "from India" to the rest of the world, nor are Ancient Indians the sole originators of the concept of dividing a circle into 360 degrees (there is no evidence the Babylonians would have gotten it from India, though it is of course not impossible both got it from an even older tradition). Likewise, most of the etymological claims are also wrong.
I'm claiming that $\pi$ did not "originate in India", as your video claims. The notion of $\pi$ is not that hard to "discover" when you're doing astronomy, and it is likely that several astronomers and geometers seperately started trying to get approximations to it without having to have been in direct communication with each other
@JackRod "calculated $\pi$ before anyone else" is not evidence that the concept spread from there
parallel discovery is possible and in this case I know of no evidence that the early Babylonians would have known of the early Indian astronomers
For instance, Mayan astronomers certainly also had some notion of $\pi$, but they can't have gotten it from either the Babylonians or the Indians, even though they might have "discovered" the concept later than those!
Astronomy and its related celestial content was found in many scriptures written thousands of years back. The planetary system, solar system, distance of every planet from earth were discovered and discussed many scholars in India.
Contents
Great Indian Astronomers · Aryabhata (476 – 550 AD)
· Brahmagupta (598 – 668 AD)
· Bhaskara II (1114 – 1185 AD)
Rotation of the Earth Gravity of the Earth The Heliocentric theory The Speed of Light Lunar Eclipse Moon – A Satellite of the Earth Orbiting Planets – Concept of Gravity
he period ranges from 6000 BCE for a direct Rig-Vedic quote to 14th century AD for Sayanacharya’s commentary. How so much of astronomical knowledge came into being at such ancient times is a matter to be reflected upon. However, there are three names in the field of ancient Indian astronomy who proved their genius as leading astronomers in the Post-Vedic period. They are –
1. Aryabhata I – 5th Century AD
2. Brahmagupta – 7th Century AD and
3. Bhaskaracharya II – 12th Century AD
A brief synopsis on their contribution in the field of astronomy has been described as below:-
they might have come up with the concepts independently, they might both rely on an even earlier unattested source or the later source may have gotten it from the earlier source
just giving a bunch of dates is not evidence which of these three is the case
@ACuriousMind what context? i placed the fact what i can provide nothing to share with someone who characterize some one with words nationalism or somerthing
@JackRod You haven't meaningfully responded to anything I've said and instead chosen to copy-paste giant quotes into the chat that don't actually address any of the specific criticisms I've made of the video you posted inviting us to share our thoughts on it.
::shrug:: all you would have had to do was to actually engage in back-and-forth discussion instead of copy-pasting only tangentially related material obviously prepared ahead of time with no regard to the specific points being made.
@JackRod Slereah is correct that there is a brand of Indian nationalism that is mostly considered ahistorical by the academic mainstream (cf. e.g en.wikipedia.org/wiki/Historiography_of_India#Hindutva_Approach), and what you seem to attempt to say is close to this ahistorical approach. It's valid criticism to point this out.
Now I have been wondering is this not what is done with Plato and the likes? People attribute every thought known to man to Plato and such but idk pretty easy to be the "originator of epistemology" if all you have to do is insert a passage about learning or something
@SillyGoose Yes, there is a similar problem in European history and a focus on the Ancient Greeks as opposed to older (often Semitic: Babylonian, Assyrian, etc.) sources
It is easy to underestimate or overestimate the original sources
People will often point out ancient egypt as an originator of greek mathematics but otoh ancient egyptian mathematic was not very based on demonstrations
A lot of it was ad hoc formulas, at least as far as we can tell
Since there weren't really mathematicians back then from what I can see
Scribes just had to figure it out for practical purpose
I generally would be very careful to claim anything about the actual "origin" of any concept in the historical record since our record of ancient times is very incomplete
you can trace certain influences, e.g. medieval European theology was explicitly influenced a lot by Plato, Aristotle, etc. and we know that because they tell us, but that doesn't mean those influences came up with the ideas, or that any other instances of those ideas must necessarily stem from the same source
You see this in non-scientific output of ancient cultures, too: There's a lot of at first glance strangely specific similarities between religious concepts (e.g. specific attributes of gods) in superficially unrelated cultures, but once you accept that there was some sort of Indo-European precursor culture the later cultures don't need to have communicated those concepts directly, they just all started with a similar set of ideas that then evolved differently over time
(of course a lot of religious similarites is also syncretism, but still)
Intellect is too nebulous. A lot of societies prize competence/intelligence, with very strict limiters.
Would a free-thinking culture be automatically better than a authoritarian one, if the authoritarian one had a really good public school/standardized test regime?
@SillyGoose This sounds as if you think ancient religion was motivated by politics. I think this is a very (post-)modern view (especially the focus on (will to) power as the drive behind "ideologies"), shaped by the structure and history of modern organized religion. I think the interplay of ancient religion and politics is interesting, but starting from the assumption that one motivated the other is putting the cart before the horse.
@SillyGoose there exists a class of institutions in India, where high school students are trained for the dreaded joint entrance exam. In such places, people don't know what smartphone is, they only know of keypad phones. Within peer groups, if you waste one second in ur life, they'll frown upon you. Idk if it inculcates intellect but certainly grit
> And Euhemerus, nicknamed Atheist, says “When the life of humans was without order, those who exceeded the others in strength and cleverness, to the point that everyone lived in response to their orders, in their eagerness to achieve more admiration and esteem made up a sort of superlative divine authority belonging to themselves, and thus were thought of by the many as gods.”
@Slereah My point is that "motivation" implies the origin of religion is some political intent. While it is absolutely true that many cultures instrumentalize(d) religion to enforce societal or political norms, I think we should not start from the assumption that that means every religion was intentionally manufactured to do that from the outset.
i think actually that i do not have a set opinion of what the origin of religion is. i guess in some circumstances 1) to explain unexplainable phenomena, 2) incentivize collaboration, 3) extortion, 4) add a missing, fulfilling dimension to peoples's lives on a large scale
though i think whatever the origin of religion may be, the interplay of politics/contemporary society with the religion is interesting. especially in circumstances in which contemporary politics/society steered a religion towards a direction not intended from the outset
Ptolemy didn't use our modern trig functions based on a unit circle. Instead of the sine, he used chords of a circle with a diameter that was convenient for arithmetic. Incidentally, early Indian mathematicians also used chords, but I can't remember if the Greeks and Indians used the same diameters. IIRC, the Indians used a couple of different standard diameters, but I read about this stuff 20+ years ago...
@SillyGoose I think it's to unify people's way of thinking, lay down a set of moral guidelines and so on. The idea might've been, in some difficult situations, people that follow the same set of rules might do better
@Slereah ...and what counts as historical evidence of it! Lots of evidence for burial rites before the invention of writing, but how would one tell whether these were "religious" in any way recognizable to us?
It is one of those things where you can tell that a lot of modern religious ideas are the combinations of a lot of disparate ideas from previous religions
A lot of religious elements that you'd think are universal from modern religions usually just appear in one or two ancient religions sometimes
People just heard about those notions and incorporated them
Speaking of trig, sine and cosine are arguably the first words that originated completely from maths. They were corruptions upon corruptions upon corruptions of earlier mistranslated words.
Some people will say that the christian god differs from greek gods for being perfect instead of a more human figure, but some people did think the greek gods were perfect inhuman figures and that representing them as such like in the Iliad was Blasphemy
@Slereah True, but hey, it was a good start. :) And sure, some of their data was a bit low in quality. It's not easy to see Mercury. I once read that Copernicus never saw it. I definitely observed it a few years ago, I might have seen it a few other times without realising.
is the personification of feelings in the romantic era an advent of the time (cf. John Keats)? it seems similar to the personification done as with say greek gods
One thing you can see also in ancient religions is how the gods are supposed to be
Sometimes they are powerful figures who run the aspect of the world they are associated to, sometimes they represent them, sometimes they literally are those things
@nickbros123 There's the notion of karma, but it is a bit different to the Abrahamic notions of sin. Karma is more like an automatic law of nature, rather than a punishment imposed by an authority. Eg, if you walk off a cliff, you'll get hurt because of how gravity works, not because the god of gravity thinks you deserve to be punished. ;)
https://www.poetryfoundation.org/poems/44478/ode-on-melancholy No, no, go not to Lethe, neither twist Wolf's-bane, tight-rooted, for its poisonous wine; Nor suffer thy pale forehead to be kiss'd By nightshade, ruby grape of Proserpine; Make not your rosary of yew-berries, Nor let the beetle, nor the death-moth be Your mournful Psyche, nor the downy owl A partner in your sorrow's mysteries; For shade to shade will come too drowsily, And drown the wakeful anguish of the soul.
@SillyGoose Okay, so indeed this is where in Ancient Greek you would often find the gods associated with the concept, e.g. "Beauty" is Aphrodite, "Psyche" is literally the name of the Ancient Greek goddess of the soul, etc.
@WaveInPlace It's like an incompressible fluid which can flow and swirl, but the zero divergence means that the volume is locally preserved, you don't have pockets of the fluid expanding or contracting.
How can an electron distinguish between another electron and a positron? They use photons as exchange particles and photons are neutral, so how does it know to repel or attract?
That just gets back to the prior gap. Light makes/has/is two types of electric field. Individually these have electric flux, though in total the flux is zero.
How do those electric fields materially differ from those of particles, aside from their balanced nature?
And if divergence is zero everywhere, how is there a net field at any given space where light is?
@JackRod What am I supposed to do with this? Again, I never doubted that the ancient Indians had math - what I objected to were the specific claims in the video you posted about e.g. the etymology of al-gabr or the claim that $\pi$ spread from India to the rest of the world. I don't understand how this article is supposed to relate to what I said.
@MoreAnonymous I guess some one did not taught you in university that there is pre dedicated courses in university of Delhi as well university of banaras even the iit humanities department have been Purusuing these course long before the event you have been Mentioning and some body did not to leave u also that goi through indira gandhi centre of arts+archaeology of survey of India have long research based course on vedic subjects so kindly go through this.
How can an electron distinguish between another electron and a positron? They use photons as exchange particles and photons are neutral, so how does it know to repel or attract?
