A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may either be scientific or other than scientific (or scientific to less extent). Depending on the context, the results might, for example, include generalized explanations of how nature works. The word has its roots in ancient Greek, but in modern use it has taken on several related meanings.
In modern science, the term "theory" refers to scientific theories, a well-confirmed type of explanation of nature, made in a way consistent with scientific method, and fulfilling the criteria required by modern science. Such theories are described in such a way that scientific tests should be able to provide empirical support for it, or empirical contradiction ("falsify") of it. Scientific theories are the most reliable, rigorous, and comprehensive form of scientific knowledge, in contrast to more common uses of the word "theory" that imply that something is unproven or speculative (which in formal terms is better characterized by the word hypothesis). Scientific theories are distinguished from hypotheses, which are individual empirically testable conjectures, and from scientific laws, which are descriptive accounts of the way nature behaves under certain conditions.
Theories guide the enterprise of finding facts rather than of reaching goals, and are neutral concerning alternatives among values. A theory can be a body of knowledge, which may or may not be associated with particular explanatory models. To theorize is to develop this body of knowledge.The word theory or "in theory" is sometimes used erroneously by people to explain something which they individually did not experience or test before. In those instances, semantically, it is being substituted for another concept, a hypothesis. Instead of using the word "hypothetically", it is replaced by a phrase: "in theory". In some instances the theory's credibility could be contested by calling it "just a theory" (implying that the idea has not even been tested). Hence, that word "theory" is very often contrasted to "practice" (from Greek praxis, πρᾶξις) a Greek term for doing, which is opposed to theory. A "classical example" of the distinction between "theoretical" and "practical" uses the discipline of medicine: medical theory involves trying to understand the causes and nature of health and sickness, while the practical side of medicine is trying to make people healthy. These two things are related but can be independent, because it is possible to research health and sickness without curing specific patients, and it is possible to cure a patient without knowing how the cure worked.
The thread https://www.physicsforums.com/threads/qft-operators-time-space-asymmetry.906369/ contains the first recommendation I have seen in these forums for Klauber's book, and instead of hijacking that thread I thought I might ask a question here. I find the book more readable than many for...
Homework Statement
A cylinder containing an ideal gas is in vertical position and has a piston of mass ##M## that is able to move up or down without friction (Fig. 13.2). If the temperature is increases,
...Fig (13.2)
(a) both ##p## and ##V## of the gas will change.
(b) only ##p## will...
Here's an interesting article from Quanta magazine:
https://www.quantamagazine.org/20170223-bootstrap-geometry-theory-space/
and some backstory:
https://en.wikipedia.org/wiki/Bootstrap_model
Hey everyone,
So I'm writing the script for a Youtube show I'm making, and it's pretty heavy on the science/physics side in terms of exposition.
So before i jump into what i want to ask let me just briefly explain the story.
A Time traveler and his time traveling machine go back 30 years in...
Let $\beta$ be an ordinal.
Prove that $A\cap \bigcup\beta=\bigcup\{A\cap X\mid X \in \beta\}$
I'm not sure on this. It looks a bit like union distributing over intersection. Please help.
The Special Theory of Relativity is based on the observations of an outside observer on a system traveling at the speed of light.
There is no single point of reference to determine speed. So speed is determined relative to another object.
This being the case an Apple traveling at the speed of...
Find a function g from {0,1} to B\A such that f^-1(g(x)) = x +2 for x∈{0,1}. Present it in the 2-row form.
A = {{1},2,3} and B = {∅,1,{2},3}
I know that B\A = {∅,1,{2}} and f is a bijection from A to B\A
how do I find such function g? It obviously can't be bijection, how do I match one value to...
Let's talk about the function ##f(x)=x^n##.
It's derivative of ##k^{th}## order can be expressed by the formula:
$$\frac{d^k}{dx^k}=\frac{n!}{(n-k)!}x^{n-k}$$
Similarly, the ##k^{th}## integral (integral operator applied ##k## times) can be expressed as:
$$\frac{n!}{(n+k)!}x^{n+k}$$
According...
Homework Statement
[/B]
How are we able to go from the first line to the second line and then the second line to the third?
Homework Equations
Euler Identity: e^j(theta) = cos(theta) +jsin(theta)
The Attempt at a Solution
This problem is more about preliminary theory in my opinion so I tried...
what is the current consensus on inflation, as recent article in SciAM
https://www.cfa.harvard.edu/~loeb/sciam3.pdf
the 3 authors are highly respected physicists in the field
they conclusion
inflation is internally inconsistent and inconsistent with best measurements from PLANCK CMB...
Hi!
I'm currently learning for my QFT exam with the book from srednicki (here as pdf: http://web.physics.ucsb.edu/~mark/ms-qft-DRAFT.pdf) and I am trying to understand the chapter "Effective field theory" (p. 185 in the pdf above)
He first introduces an ultraviolet cutoff Λ and then computes...
Hello, here there are 2 things (one about hologramic universe and the other about a quantum physics test similar to the slit lamp.
The first one is about the Bohm and Pibram as well as one about Alain Aspect 1982 study: articles about their theories...
I had heard of adinkras but didn't realize that they were meant to play this role. Nor did I realize that the representation theory of supersymmetry is mathematically underdeveloped.
Why the center of Newton's ring is dark? though I am thinking the path difference in the center is zero between two reflected rays...
so,I will be glad if you give the correct information about that...
I need details on this topic ,this is my assignment but my solid state physics is not so good,and don't know much about it but i have to do this assignment ,i have material on reciprocal lattice but for only including in assignment ,not for my understanding,so i directly need any material on...
Does anyone know of a book or web page that gives a history of the concept of a module and the history of modules in algebra ...
i have not not been able to find a book that covers the history of modules nor a website ...
Help will be appreciated...
Peter
Anyone familiar with possibility theory and possibilistic analysis? I came across it during my own research on expert human reasoning/decision making.
Here is a brief description of possibility theory from a recent article behind a paywall.
As I see it, possibility theory offers a novel way...
Hello everybody! I hope you are having a great day !
My question: is the strings theory a REAL theory ... is it really the final answer to the relationship between relativity and quantum mechanics! ? [emoji54]
Has anyone heard of "Bauer's Paradox" in Einstein's working out his equations for General Relativity? The description I came across was extremely fuzzy (something about an expression for a certain tensor adding up to be zero when it shouldn't, or vice-versa), so I am looking for a better...
If light is pure energy, then how can gravitational lensing work? And if light has some mass, how can it change directions instantly when it is traveling through a prism? My high school science teacher had no answer 45 years ago.
I bought a maths book and have discovered it's somewhat above my level.
In particular I'm confused about one bit of notation. I understand the "is a member of" operator when it takes a set as argument (e.g. n ∈ ℝ) but not when the book uses it with functions (e.g. n ∈ f)
Does n ∈ f mean that...
Homework Statement
Find all integer solutions to x2 + y2 + z2 = 51. Use "without loss of generality."
Homework Equations
The Attempt at a Solution
My informal proof attempt:
Let x, y, z be some integers such that x, y, z = (0 or 1 or 2 or 3) mod 4
Then x2, y2, y2 = (0 or 1) mod 4
So x2 +...
i have found one article state something like this:"""Any real evolution (macroevolution) requires an expansion of the gene pool, the addition of new genes (genons) with new information for new traits as life is supposed to move from simple beginnings to ever more varied and complex forms...
I often read about how famous theoretical physicists have made ground-breaking contributions to physics, but I always end up wondering how they are able to "discover" something that they have never seen or experienced. I believe that it has to do with the application of mathematical theories to...
My question is very simple.
As far as I know, once upon a time there was the Lorentz Ether Theory. This theory admitted existence of so-called Ether as a certain preferred frame, which was undetectable because of physical contraction of moving material bodies in direction of their motion.
In...
so, i love physics, and the more i look the more it seems our understanding of things are wrong. no planet #9, but now a mysterious planet-nine, dark energy, etc etc.
so my question probably lies in theory, but getting close to applied physics.
planet-nine, from what i have seen, the...
I'm having a bit of trouble with counting the number of physical ("propagating") degrees of freedom (dof) in field theories. In particular I've been looking at general relativity (GR) and classical electromagnetism (EM).
Starting with EM:
Naively, given the 4-potential ##A^{\mu}## has four...
Hi,
I have recently began studying quantum field theory and have just seen how the quantization of the complex scalar field, noting that there is invariance of the action under a phase rotation shows the existence of antiparticles.
I just have a couple of questions, apologies in advance if...
This was off-topic in the thread on vacuum fluctuations where the quote appeared, so I opened a new one.
I didn't know the paper before, so first need to read it...
It seems that the latest data out of CERN suggest a mass of the Higgs Boson that is smack in the middle of what would be suggested by parallel universes/string theory and SuSy.
Do you think Edward Whitten, Savas Dimopoulos, and probably others could get together in a room to unify these two...
Homework Statement
Hi,
Please see attached.
I am trying to show the second equality , expressing all as a total derivative (I can then show that ##\delta S = ##)
Homework Equations
See above
The Attempt at a Solution
So the ## m ## term is pretty obvious, simply using the chain rule.
It...
Orch theory explains consiousness of human brain as a quantum related phenomenon. These quantum processes occur in microtubules. But at this temperature quantum computation is not possible. So what is the perspective of quantum physicists on this theory.
Hi all,
I was reading Arnold Neumaier's excellent article on the Vacuum Fluctuation Myth, and ran upon one part I have a question about: he notes that "in bare quantum field theory with a cutoff, the vacuum is a complicated multiparticle state depending on the cutoff – though in a way that it...
Homework Statement
Homework EquationsThe Attempt at a Solution
I've got a feeling that the problem is either incomplete or unclear, because so far I've come up with nothing but vague ideas.
If it is clear, then please let me know so this thread can be closed/deleted.
Hello
Please see attached page from a textbook. Can someone explain why H = 4f.le.vo^2/2d.g and why delta H is given by the expression in the book? Note that the figure it mentions is on the top of the page. I have tried for days here.
Thanks
Are there any good examples of how group theory can be applied to solve multivariate algebraic equations?
The type of equations I have in mind are those that set a "multilinear" polynomial (e.g. ## xyz + 3xy + z##) equal to a monomial (e.g. ##x^3##). However, I'd like to hear about any sort...
Dear all,
recently I'm reading up some string/M-theory, especially the role of branes, because I'm writing a popular science book in Dutch. Every textbook states the issues one encounters when you try to quantize p-branes for p>1, as is discussed e.g. here...
I read Lucien Hardy's paper whose tittle was "Quantum Mechanics, Local Realistic Theories, and Lorentz Invariant Relativistic Theories". There, he argued that lorentz invariant observables which involved locality assumption contradict quantum mechanics.
I tried to follow his argument, but got...
Homework Statement
If someone on a spaceship looked at a clock on Earth traveling at 99.5% the speed of light what would they notice?
Homework EquationsThe Attempt at a Solution
Would they notice that time is faster on earth? Is my assumption correct
can string theory reproduce hawking radiation in non-extremel black holes in 4D? i.e physically realistic black holes. do they exactly match hawking's calculations?
what is the interpretation of hawking radiation in string theory?
I was quite distraught knowing that chegg.com has no textbook solutions for "measure theory" even though it has four for abstract algebra. Could it be that the textbooks are called something else?
Hi all.
I am looking for a book in Quantum Field Theory, not for the first read. I have already studied it for university purpose, but now i would like to study the subject again from a book to cover holes and have a deeper understanding before starting a possible PhD.
I heard about Srednicki...
I'd really like some help in answering the next question...anything that might help will save my life:
F is defined this way: F:A→B where A,B⊂P(N) and P(N) is the power set of the naturals.
Let S,R∈A such that S is a proper subset of R if and only if F(S) is a proper subset of F(R)
My question...