The h Bar

12:32 AM

this is probably a rather stupid question, but:

i have read that the strings in string theory can be described as harmonic oscillators.

is there an equation that describes this specific oscillator? by which I mean, i know there's a general equation for harmonic oscillators, but what is the specific version of this for strings?

(hopefully i phrased that properly.)

heather

12:45 AM

would it be equation (12.95) here (google books link)?

vzn

1:14 AM

4

Q: How is a string in string theory different from a harmonic oscillator or a point?

I am reading String Theory and M-Theory: A Modern Introduction by Becker, Becker and Schwartz. I've tried to read this book before but not succeeded because I didn't know enough math or physics. This time, I feel like I am following it much better but I still don't understand what a string is. ...

heather

@vzn i saw that, but i don't know what equation the comments are referring to, and neither question nor answer have any equation at all.

vzn

2:08 AM

@heather yes the question was very nontechnical and the answer got very technical/ specialized as it went on. havent studied this much but afaik "worldsheets" are a lot like "tubes" expanding/ contracting harmonically thru time. the sides of the tube behave nearly like harmonic oscillators. presumably a close connection with de broglie waves.

May 18 at 16:49, by vzn

@Slereah )(

heather heres a fun ref maybe will check it out myself sometime :) dummies.com/store/product/…

vzn

3:10 AM

in Mathematics, Apr 26 '16 at 23:45, by Balarka Sen

Steven Sagona

3:51 AM

(not an expert on string theory) but in quantum field theory, many "particles" of a field (think of how photons make up the electric field) can be constructed as being energy states of a harmonic oscillator

the particles in a feynman diagram (constructed when doing perturbative calculations in field theories) are often already these energy states of a harmonic oscillator

(from what I read on wikipedia), string theory extends these feynman diagrams to being 2D instead of 1D diagrams (which basically means these point-like particles are now 1D "strings") But I want to point out that without talking about the vibration of these "strings", the states these strings are supposed to describe /already/ are energy states of a some harmonic oscillator.

vzn

29

Q: Number theory and physics

I was following some lectures by Edward Frenkel about Langlands correspondence. He was describing some analogies between number theory and theoretical physics (Mirror symmetry). At some point ( my lack of knowledge) I had the impression that the relation between number theory and "real" physics i...

nt.number-theory mp.mathematical-physics langlands-conjectures physics geometric-langlands

Semiclassical

4:29 AM

@vzn on that note, if I'm still in minnesota come november I'm definitely going to sit in on this: ima.umn.edu/2018-2019/SW11.14-16.18

2

not that I imagine I'll understand it

user187604

8:56 AM

Can someone explain why tension of a wire is electromagnetic force?

@ACuriousMind can I ask homework - type questions here?

Nehal Samee

@user187604 problem solving room might be okay ...

user187604

@NehalSamee so is the ultimate answer no? Please

@NehalSamee I mean please clarify?

bolbteppa

9:33 AM

@heather the equations of motion for a string are wave equations, you can interpret waves as a collection of harmonic oscillators image.slidesharecdn.com/…

bolbteppa

11:16 AM

Finally! Since Majorana spinors satisfy
\begin{align}
\overline{\psi} \rho_a \psi = - \overline{\psi} \rho_a \psi = 0
\end{align}
we see, using the spinor covariant derivative
\begin{align}
\nabla_a &= \partial_a + \frac{1}{4}\omega_a^{\mu \nu} \Gamma_{\mu \nu} \\
&= \partial_a + \frac{1}{8}\omega_a^{\mu \nu}[\rho_{\mu},\rho_{\nu}],
\end{align}
and the Clifford relations
\begin{align}
\{ \rho^a,\rho^b \} &= - 2 \eta^{ab}, \eta^{ab} = (-1,1), \\
\{\rho^0,\rho^0 \} &= - 2 \eta^{00} \\
2(\rho^0)^2 &= - 2 (-1) \\

Completely ignored the whole Majorana aspect of this for so long :\

Probably a shorter method, but yes!

Novalium Company

Afternoon.

Slereah

12:19 PM

Hello

Secret

12:41 PM

[Random]

arxiv.org/abs/1802.00651

that is NOT a paper. No physics paper except the 1980s has only 3 pages

not to mention, the maths is completely and utterly topologically discombobulated

13

Q: If you can be "discombobulated", is it possible to be "combobulated"?

I've often heard the word "discombobulated" used. But I've never heard of something being "combobulated", and it's not in any dictionary I've looked at. If "combobulated" is not word, where did "discombobulated" come from?

etymology

Googleing for wormhole physics:

arxiv.org/abs/1805.03781

What's the point if it still requires a huge amount of exotic matter

When Time Travel is possible

►

arxiv.org/abs/1707.07439

I don't think so

arxiv.org/abs/1805.03035

> In view of the classical solutions to the field equations
presented here, it seems reasonable not to rule out the
possibility of having to accomodate causality violation
even within classical gravity. Such spacetimes, allowing
a continuous transition to zero signature, should also
be relevant in a formulation of quantum gravity where
change of signature or of topology [16] could play an important
role.

(hmm... I cannot believe there is actually something worthwhile here while it is never my intention to be so... Nature, you seemed to be getting even more cunning ever since the day when The Plan enters real life becomes clear... What exactly are you up to...)

jots in notebook

(O btw, it has reached critical mass already, we should get ready)

Finally, after almost a decade of operation. The Plan finally managed to penetrate The Barrier. We will be anticipating its arrival tomorrow as we started to retract The Darkness in Hong Kong

smh.com.au/world/asia/…

Trump Cancels Meeting with Kim Jong-un, Asparagus Day - Monologue

►

and then, stupid Trump and Xinjinping is has to go against our will

It does not matter, nature

This is the 21st century, and you cannot protect The Great Evil forever

Now that The Plan have finally materalised in this reality from pure fantasy, we have a lot of work to do as everyone else get utterly discombubolated confuzzleablited. The Great Evil will be erased!

Lozansky

1:02 PM

Yo @Secret

Secret

@Lozansky hi

Lozansky

Is there a name for the somewhat stronger dipole-dipole attraction between molecules with permanent electric dipole moments (e.g. $NH_3$ and $H_2O$)?

Secret

uh, if there is X-H where X is electronegative like O, N, F, then it is called a hydrogen bond

Lozansky

In the case of no permanent dipole moment, it would be the London force

Secret

There are also let common ones such as halogen bonds

Lozansky

1:05 PM

Aren't hydrogen bonds generally pretty damn strong?

Secret

yeah, they are generally much stronger than dispersion and some ion dipole forces

I don't know if there is a category for intermolecular forces between hydrogen bond and dipole dipole

Lozansky

What force is responsible for forming crystalline solids in the case of molecules with dipole-dipole moment?

Secret

is the solid consists entirely of polar molecules with no hydrogens?

Lozansky

Uhm I guess it could be either (hydrogens or no hydrogens)

Secret

if it contains H attached to O,N, F (and sometimes Cl) then it will be mainly hydrogen bond. If it is polar with no H, then it has to be mainly dipole dipole unless it is very large and hydrophobic, then dispersion dominates

Lozansky

1:20 PM

Is the dispersion effect amplified by instantaneous induced dipole moment or does it just come from the intrinsic dipole-dipole attraction?

Secret

For large polar molecules, both dipole -induced dipole and dispersion are important

Lozansky

Alright, cool!

Hmm, my book says that potassium has a single $3s$ electron

Surely that's not right?

Secret

I will imagine that should be a 4s since K i period 4?

Lozansky

Yeah, should be $1s^22s^22p^63s^23p^64s^1$

Secret

yup looks right

Akash. B

1:38 PM

guys I have a question

what caused big-bang?

Secret

What Came Before the Big Bang?

►

Akash. B

@Secret okay thank you

Sir Cumference

@Akash.B No one really knows what the Big Bang is

It's the moment where the amount of space in the universe goes to zero

Akash. B

@SirCumference then on what basis this theory proposed?

Sir Cumference

General relativity

Also the Hubble law

Akash. B

1:49 PM

guys another question

in Problem Solving Strategies, Apr 29 at 8:35, by Akash. B

4 hours ago, by Akash. B

@JohnRennie sir according to string theory, how can an object travel through another dimension of space

@SirCumference ^^

Sir Cumference

@Akash.B I don't know anything about string theory, sorry

I don't think many people here do either

abhishek chaudhary

2:05 PM

i think rutherford was right

bolbteppa

@Akash.B in non-relativistic mechanics, a particle is given by specifying 3 space coordinates as a function of time, $(x(t),y(t),z(t))$, in relativistic mechanics and general relativity you must consider four space-time coordinates $(t,x,y,z)$ and treat a particle moving through spacetime as a curve. String theory just assumes a curve (the string) instead of a point sweeps through spacetime to generate a surface,

and it turns out the dimensions of space-time have to go above 4 for it to make sense

@Slereah contrarian you

Secret

slereah does not exis- ::dies::

Lozansky

2:23 PM

Are conductivity and number of excited (to the conduction band) electrons directly proportional?

John Rennie

2:34 PM

@Lozansky no, there are two competing effects.

Increasing temperature excites more electrons to the conduction band, and that does increase the carrier density and hence the conductiviy.

But it also increases the scattering off the lattice due to the increased amplitude of lattice vibrations, and that decreases the conductivity.

Which effect dominates depends on the material. For semiconductors thermal excitation usually dominates and their conductivity goes up with increasing temperature. For metals scattering dominates and their conductivity goes down with increasing temperature.

Lozansky

Okay, but if the temperature change is small in comparison to the change in conductivity, then it is a fair approximation to attribute the change in conductivity solely to the change in charge carriers? (But still accounting for the change in temperature)

gateprep

Explain me why work hardening takes place at molecular level

I don't get it

@JohnRennie

Lozansky

@JohnRennie Oh okay my book does mention this approximation (although without justifying it) so I think we are good :)

gateprep

anyone with my answer please explain how dislocation leads to this

@JohnRennie@Lozansky

Lozansky

2:50 PM

Sorry no idea

gateprep

@JohnRennie ??

Why do we even use engineering stress?

the answer is there in this link but I can't understand

7

Q: Why do we even use engineering stress?

Surprisingly this hasn't been asked before, so I must be missing something simple. We use engineering stress and engineering strain in this eq. Stress = (Young's modulus) × (strain). This eq. is used in analysis of bending beams, twisting shafts and in buckling. So the final equation of bending...

materials structural-engineering stresses

@JohnRennie Pls help about this

Secret

when is skullpatrol when we need him?

(O wow, that is the first time I saw THAT) ---------------------------------------------------------------------------------------------------------------------------------------------------------->

John Rennie

3:37 PM

@gateprep in metals ductile deformation occurs mainly due to the motion of dislocations.

In work hardening we deliberately deform the metal to force all the dislocations to move to points where become pinned and cannot move any farther.

Since the dislocations now cannot move the metal will not deform under load until that load approaches the fracture stress.

gateprep

4:56 PM

How to visually understand that dislocation moves on a slip plane?

@JohnRennie This is not answered.Please answer me properly.

0

Q: How to visually understand that dislocation moves on a slip plane?

When we look at images of edge or screw dislocation, it seems as if the direction in which that dislocation will move is already fixed by the 'way the dislocation is present'. For example, take any image of edge dislocation, and say the top half is moving with respect to the bottom. However: ...

metallurgy

Danu

Please answer me properly and promptly, John.

Tick-tock

Tick.... Tock.

Phase

The clock's ticking, Mr Rennie.

Danu

Wheeeeeere's Johnny?!

Loong

5:11 PM

rennie.co.uk

2

Eulb

@Phase sup

Phase

the void

I have a song recommendation though. Check discord in a second.

CooperCape

5:29 PM

Last day of school today... (aside from exams).

But they dun count

enumaris

how can exams not count

Slereah

0

Q: Physics blogs maintained by famous physicists

I'm not sure whether I'm allowed to ask this question here. If not, I'll delete the question. I wanted to know what are some physics blogs maintained by famous physicists and talk about physics concepts. I'm already aware of Sean Carroll and Lubos Motl's blogs. Thanks!

resource-recommendations

If I answer "Motl isn't famous", will I get in trouble

CooperCape

@Slereah I think you'll find he's my home screen background...

@enumaris cause like no more lessons etc. (Is kinda what I meant)

enumaris

exams are the fun part tho

CooperCape

Depends if they're chemistry or not.

Novalium Company

5:44 PM

Evenin'

CooperCape

hallo

Novalium Company

Hola.

Captain Bohemian

@CooperCape is a chemistry exam not fun?

CooperCape

@CaptainBohemian Not if you know as little as I do :p

Phase

@Slereah I would suggest that rather than "Motl isn't famous", point out that "infamous" is the better word

Captain Bohemian

5:51 PM

@CooperCape I only know chemistry of high school level and have forgotten a great part which isn't closely related to physics. My physics department only had chemistry course in the first undergraduate year and the chemistry being taught during that year has never been used in later courses or research.

CooperCape

This information pleases me.

enumaris

I never had to take chem in Uni cus I took AP chem in high school :D

Captain Bohemian

Does chemistry knowledge have much use in physics? I feel most material in chemistry seems to never have use in physics.

Novalium Company

Guys, can you change universities? I mean, let's say I finish high school and I choose to go to some university, but I don't like it, can I apply for another one?

CooperCape

Sure, you'll just probably have to take a year out and re-apply for undergraduate (losing hella money in the process).

That's what it's like in the UK at least, don't know bout other places.

Novalium Company

5:56 PM

What is undergraduate

@CooperCape in which uni r u?

CooperCape

Undergraduate students are those that have yet to graduate i.e in first/second/third year of degree.

Captain Bohemian

@NovaliumCompany well, I think that depends on your country's education regulation. In my country, we can transform to another university in the second year if we pass the transforming-school exam of the university we want to transform into, and if we pass, we will be the second year student of that university.

CooperCape

@NovaliumCompany Not at uni yet, have a place in Manchester if I get the grades.

Novalium Company

Because I took a look at Elon Musk's education and it has quite a lot of universities there. Has he even finished one?

google.bg/…

Guys, any good book recommendations. Sci-fi, Adventure, something like this?

gateprep

0

Q: How to visually understand that dislocation moves on a slip plane?

When we look at images of edge or screw dislocation, it seems as if the direction in which that dislocation will move is already fixed by the 'way the dislocation is present'. For example, take any image of edge dislocation, and say the top half is moving with respect to the bottom. However: ...

metallurgy

I could understand even a bit of this explanation pls help

Phase

6:16 PM

Tick tock, mr Rennie

enumaris

6:32 PM

tick tock

John Rennie

Hmm

@Loong no relation unfortunately, otherwise I'd be spendng my time in a villa in the South of France, not on the Stack Exchange :-)

Loong

hehe

gateprep

@JohnRennie pls answer my doubt pls

Its urgent

Sir

John Rennie

6:48 PM

@gateprep I don't know much about metallurgy I'm afraid.

gateprep

pls tell me what u explained me there

Its mostly crystallogrpahy

@JohnRennie

the answer is writeen in the link which I cant get

Novalium Company

7:01 PM

Guys, irrational numbers are the ones who 'continue' forever right? Like pi...? I mean, is that what an irrational number is? Because I'm trying to learn about rational and irrational numbers.

John Rennie

@NovaliumCompany an irrational number is one that cannot be written in the form a/b where both a and b are integers.

Novalium Company

It can't because a and b will continue forever right?

John Rennie

That means its representation in decimal cannot ever terminate because if it did terminate it could be written as an integer divided by $10^n$ where $n$ is the number of decimal places before it terminated.

Novalium Company

Ok, can't I just write the square root of 2 over 1? The square root of 2 is an irrational number.

John Rennie

Square root of 2 isn't an integer

Novalium Company

7:07 PM

$sqr(2)$ testing

You mean $\sqrt{2}$

how?

How what?

Nvm. So $\sqrt{2}$ is an irrational number right?

John Rennie

Yes, there is a famous proof that $\sqrt{2}$ cannot be written in the form a/b where a and b are both integers.

That proof dates back to Ancient Greece I think.

Novalium Company

7:10 PM

I mean, a rational number will be for example 5.25 where it can be expressed as $\frac{525}{100}$. Well, $\sqrt{2}$ can also be expressed as $\frac{\sqrt{2}}{1}$, why isn't it a rational number since it can be expressed as a over b?

Sid

@NovaliumCompany a and b both should be rational.

Novalium Company

Pff... I can't understand rational and irrational numbers. I'm so stupid.

John Rennie

@NovaliumCompany because for a number to be rational you have to be able to write it in the form a/b where both a and b are integers.

Novalium Company

Ok, what should I imagine when someone says a rational or irrational number?

Sid

Oh, right. Sorry, they are supposed to be integers..

Novalium Company

7:14 PM

Can you give me examples to determine if something is rational or irrational, please?

dmckee

@JohnRennie There is a similar easy construct for finding the rational expression for repeating decimals.

John Rennie

@Sid well, a and b can be rational because in that case they are easily converted to integers.

dmckee

@NovaliumCompany You seem to be ignoring an important part of the definition. Rationals can be written as $a/b$ for $a$ and $b$ both integers (and b non-zero).

Novalium Company

So $\frac{5.25}{3.10}$ is not a rational number?

John Rennie

@NovaliumCompany multiply the top and bottom by 20 and you get 105/62

dmckee

7:18 PM

@NovaliumCompany The key to that is "can be".

Novalium Company

Got it, and if I tried that with pi, it wouldn't work because pi continues forever, so we can't get it to be an integer, that's why it's an irrational num?

John Rennie

Yes

dmckee

When you see something that is not already expressed as a grade-school fraction, you don't know if it is or is not a rational right off: you have to think.

John Rennie

In fact pi is transcendental as well as irrational :-)

Novalium Company

what is a transcen...?

John Rennie

7:19 PM

Google it :-)

Novalium Company

ahh, fineee :D

dmckee

Uhm ... is

"Famous like Sean Carroll and Lubos Motl" is tantamount to "famous like Led Zeppelin and the rock band I was in when I was fourteen". — AccidentalFourierTransform 49 mins ago

"not nice"?

As long as were talking about classes of numbers, we should perhaps bring up the algebraic numbers.

I have it in my head that the strictly real subset of them includes irrationals, but not transcendentals. But I can't think why.

Anyone?

Novalium Company

Ok guys, thank you. I finally know what a rational and irrational numbers are.

dmckee

::cheers::

Always glad to actually help out.

Novalium Company

I'm so glad to be part of this amazing community. Most of the people are so helpful and nice.

Sid

7:23 PM

@NovaliumCompany Unfortunately, not everyone thinks so.

John Rennie

2 hours ago, by Slereah

If I answer "Motl isn't famous", will I get in trouble

That would be a yes then :-)

@NovaliumCompany if you're in need of further entertainment, there are an infinite number of rational numbers and an infinite number of irrational numbers, but the two infinities have different sizes.

Novalium Company

Yep, I've heard that infinities can vary in size, which is weird and confusing :D

dmckee

^ Always good to set brains dribbling out of ears.

Sid

@JohnRennie Aren't almost all irrational numbers transcendental?

John Rennie

@Sid I have absolutely no idea :-)

I've always regarded number theorists as an alien race

dmckee

7:27 PM

@NovaliumCompany George Gamow's book "One, Two, Three ... Infinity" is kinda long in the tooth but it covers this very well at a pop-math level.

Sid

I mean, it's hard to prove but when you think of it, it feels that way.

dmckee

You might find it at a nearby library.

Novalium Company

@dmckee I'll give it a look and probably read it. So it covers the basics of math?

John Rennie

@Sid apparently the irrationals that aren't transcendental (i.e. the algebraic numbers) form a set of size $\aleph_0$

dmckee

@NovaliumCompany I don't recall in detail what it covers, but Cantor's diagonal slash argument (which proves the different sizes of the integers and reals) is definitely in there.

John Rennie

7:29 PM

And since the irrationals form a set of size $\aleph_1$ there are infinitely more transcndental irrationals than non-transcendental irrationals.

Novalium Company

@dmckee The book looks complicated.

dmckee

Now, now, your notation is assuming the continuum hypothesis.

@NovaliumCompany It is a surprisingly easy read.

Gamow was a moderately famous physicist, but he was also a very clear writer.

Captain Bohemian

@Sid this is the first time I hear the term transcendental: Of or relating to a real or complex number that is not the root of any polynomial that has positive degree and rational coefficients.

Novalium Company

I'm looking at it right now, and looks complicated, with complicated logic and words. ;\

I'll maybe watch Khan's vids or take math for dummies.

Lozansky

Say we have a hydrogen atom in the state $(n,l,m_l,m_s) = (2,1,0,1/2)$ and we are interested in finding the angles $\theta$ where the probability is the highest for finding the particle

Would we consider the magnitude of the angular part squared i.e. $|Y^{m_l}_l|^2 = |Y^0_1|^2 = |\sqrt{3/4\pi} \cos \theta|^2 = 3/4\pi \cos^2 \theta$ and look for its maximum values?

Or would we integrate $|Y_1^0|^2$ over $r$ with the volume element $dV = r^2 \sin \theta dr d\theta d\varphi$?

enumaris

8:08 PM

the first one

Emilio Pisanty

8:18 PM

"Famous like Sean Carroll and Lubos Motl" is tantamount to "famous like Led Zeppelin and the rock band I was in when I was fourteen". — AccidentalFourierTransform 2 hours ago

2

Hitting the nail on the head

Somebody please star that

(or don't, y'know)

enumaris

lol

bolbteppa

8:38 PM

Motl invented matrix string theory fyi

Matrix string theory

In physics, matrix string theory is a set of equations that describe superstring theory in a non-perturbative framework. Type IIA string theory can be shown to be equivalent to a maximally supersymmetric two-dimensional gauge theory, the gauge group of which is U(N) for a large value of N. This matrix string theory was first proposed by Luboš Motl in 1997 and later independently in a more complete paper by Robbert Dijkgraaf, Erik Verlinde, and Herman Verlinde. Another matrix string theory equivalent to Type IIB string theory was constructed in 1996 by Ishibashi, Kawai, Kitazawa and Tsuchiya. This...

Emilio Pisanty

@bolbteppa you have a weird fameometer

bolbteppa

It would be weird if I brought up Motl's olympiad score as his claim to fame :p

Semiclassical

Yes, it would :)

Emilio Pisanty

0

Q: Complete E and B field functions

How does the complete E field function looks like? At least one person marked this question as favorite, so it should be usefull for him. https://ru.wikipedia.org/wiki/%D0%A3%D1%80%D0%B0%D0%B2%D0%BD%D0%B5%D0%BD%D0%B8%D1%8F_%D0%9C%D0%B0%D0%BA%D1%81%D0%B2%D0%B5%D0%BB%D0%BB%D0%B0#%D0%9F%D0%BE%D0...

electromagnetism classical-electrodynamics

Damn

I blew a chance to dupehammmer on an Unclear vote

Novalium Company

Guys, I saw something very weird in a video. youtube.com/watch?v=hI9CaQD7P6I Take a look at the line where it says $a^2 = ab$

Anyone?

enumaris

8:53 PM

can't view youtube

Novalium Company

Ok it says that $a = b$ and $a^2 = ab$

Well, shouldn't $a^2 = aa = bb = b^2$?

Or he just did it to prove the point that you can't divide by 0.

Well nvm, I'll go to sleep, it's really late.

enumaris

if $a=b$ then you can certainly say $a^2=ab$

Balarka Sen

@Sid Correct; algebraic irrationals are solutions to $\sum a_i x^i = 0$ for rational $a_i$'s. So that set is at least as large as the set of all finite tuples of rational numbers (by sending a polynomial to it's tuple of coefficients) (in fact smaller because $c \cdot p(x) = 0$ and $p(x) = 0$ have the same solutions). But that's just $\bigcup_{n \in \Bbb N} \Bbb Q^n$, which is a countable set.

Just dropping by to answer that question

dmckee

Ouch ... threepanelsoul.com/comic/high-society

enumaris

also blocked

all webcomics block grrrr....

Balarka Sen

9:06 PM

Relevant thoughts: By Liouville's theorem, algebraic numbers cannot be well-approximated by rationals. So if you pick a random converging sequence of rational numbers, somehow that should mean with probability 1 you'll land into a transcendental.

enumaris

wat

Balarka Sen

That's obvious in retrospect as algebraic numbers form a countable set, but still.

hmmm

Anyhow, cya.

Uhm

9:13 PM

hrm

Lozansky

Can anyone explain this approximation for the atomic radius of $^{90}$Sr?
$R \approx R_0 \cdot (90)^{1/3} \cdot 10^{-15} = 1.2 \cdot (90)^{1/3} \cdot 10^{-15} = 5.4 \cdot 10^{-15} m$

I don't know what $R_0$ is

Oh wait, I found a Wiki article on it

enumaris

is that atomic radius or nucleus radius? seeing 10^-15m suggests to me that's approximating the nucleu's radius and not the atom's radius

Lozansky

Oh yeah, it's the nucleus radius

Similar names in my language :P

enumaris

The nuclear radius (R) is considered to be one of the basic quantities that any model must predict. For stable nuclei (not halo nuclei or other unstable distorted nuclei) the nuclear radius is roughly proportional to the cube root of the mass number (A) of the nucleus, and particularly in nuclei containing many nucleons, as they arrange in more spherical configurations:

The stable nucleus has approximately a constant density and therefore the nuclear radius R can be approximated by the following formula,

en.wikipedia.org/wiki/Nuclear_structure see there for specific models

Lozansky

Yup I found it explained here en.wikipedia.org/wiki/Charge_radius

Physics Meta

11:17 PM

0

Q: How to view answers to a closed question?

I have a question which was asked on this site, but then deleted: namely the answer to "How to use the book Classical Electrodynamics by J D Jackson? [closed]" referenced here when I was doing research: Pedagogy of Jackson's Electrodynamics Now I don't want to ask it since if the original was c...

discussion

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