Planck Definition and 393 Threads

As a physics undergrad, a set of natural units is nothing strange to me, we use them all the time. Having said this, I've never used Planck units. Does any area of research use them on a typical day in the office? There also seems to be this idea that I hear from time to time, perpetuated by...

https://arxiv.org/pdf/1708.01789.pdf In line whit LQG which renders time(Tomita time) to evaluated differently. Would it be possible for a bounce scenario in Blackhole. This is the update from the old paper of Planck Star http://arxiv.org/abs/1401.6562 . -- It is something to with how time...

Hi everyone, I just have some confusion regarding Planck's and Einstein's equation. The following is an explanation of the photoelectric effect using Einsteins theory: Light is composed of photons. Each photon has energy hf and mass hf/c^2. When ultraviolet photons are brought to rest by zinc...

Can someone clarify this for me. Is it the case that Planck scale unit is the smallest unit of measurement that can can observe/make, but not the smallest unit of measurement that exists? If so, is there some name for that which is smaller? Is there some fundamental measuring unit that...

I've heard that Planck length is the smallest length ever! but if something that his length is equal to Planck length and moving by speed dv which is infinitesimal change in speed or higher than that , then according to special relativity his length must be equal to L'=L \sqrt1-v^2/c^2 which...

What is the surface area ("surface volume") of a 3-sphere having a radius of 2 Planck lengths? Is the product of the Planck's constant, Einstein's proportionality constant and Planck time also equal to this volume? Does this equivalence signify anything? What does it signify?

Are the current dark matter detection experiments sensitive to Planck mass WIMPs? I've just looked at the Wikipedia WIMP article. It shows the excluded parameter space for the CDMS experiment with WIMP-nucleon cross section vs WIMP mass curves but they only go up to a WIMP mass of 1000 GeV.

I've read several articles discussing how Max Planck decided to assume that the energy radiated by oscillators in a black-body came only in discrete increments of En = nhf, where n is an integer. Using this concept, he determined that the average energy of an oscillator was given by...

Is there any experimental proof which shows that the force of gravity works at Planck length? Has it been verified already? Is it verifiable?

The reciprocal of the Planck length, ##\Lambda=1/l_P##, is used as a high-frequency cutoff in the particle-physics estimation of the vacuum energy. For example in "the cosmological constant problem" Steven Weinberg says that summing the zero-point energies of all normal modes of some field of...

Erebon theory is a novel explanation of dark matter recently invented by Roger Penrose. Erebons are scalar particles of the order of a Planck mass which can only interact gravitationally. When erebons decay, they release their energy as oscillating classical gravitational waves on the order of...

Imagine a cubic volume of space, defined today, with edges of the order of the Planck length. As cosmological time goes forward this volume expands so that the edges of the cube expand with the scale factor. This seems ok. However, as physics is time-reversible, it should be valid to imagine...

Theres something that bothers me, We claim that electron is a point particle.From that, Can we assume the volume the electron is ##(l_{h})^3## ( where ##l_h## is Planck length ) ? We know that every information can be described in bits like volume is ##(l_{h})^3## so, In every bit of...

The definition of the Planck length I have found is that it is the shortest length that has meaning. What is meant by that? Can someone give be a better definition of what it is?

By using particle physics natural units with ##\hbar=c=1## so that Planck's length ##l_P=(8\pi G)^{1/2}## we can express Einstein's field equations as $$G_{\mu\nu}=l_P^2\ T_{\mu\nu},$$ where ##G_{\mu\nu}## has dimension ##[\hbox{proper length}]^{-2}##, ##l_P## has dimension ##[\hbox{proper...

current proton decay experiments disfavor popular GUT like SU(5) Does the hiearchy problem for the higgs field require that the higgs couple to a GUT scale, if it exists, or to a Planck scale? does this require the higgs couples to Planck mass quantum mechanical black holes? since the Higgs...

I am well aware that spatial discreteness is in conflict with Lorentz-invariance. If there were a theory of QG that proposed Planck time as the smallest interval of physical time, would that be in conflict with Lorentz-invariance?

It will take a particle accelerator that size of the solar system or more to peek inside the Planck scale.. does this mean the Planck scale is a no man's land.. or empty? but for a passing electromagnetic field or strong field.. doesn't it pass thru or touch the Planck scale at all? If it...

Reading some of the critics and defenders of inflation in various papers, one thing I note they have in common is that both seem to agree the plateau models of inflation are favoured by Planck. According to one of the critics of inflation "The plateau-like potentials selected by Planck2013 are...

I've read up on the history of quantization and I can't seem to find a definitive answer on why Planck actually quantized light. Some sources say that he came up with the idea of energy being quantized in order to solve the blackbody problem, whilst others say that he was trying to create a more...

I am now working on Thermal and Non-thermal light emission of materials, particular concerning the Planck law and Generalize Planck Law. I really want to understand the fundamental concept of this. So could you please suggest me some material, book on this subject? Thank you so much in advance,

ħello. Here is my question: Has the so-called "planck length" (~1.61622837 * 10^(-35) meters) been derived with mathematical rigor within standard quantum field theory? If so, I need help finding this proof. Any literature would be appreciated. Also: If it has, then doesn't this imply a...

Hi all, This is a followup to a question from a couple of months ago regarding vacuum energy and cutoffs, basically to clarify some ideas. Given the usual picture of the vacuum as containing quantized harmonic oscillators at every point, it is not possible to apply a 'fixed' energy cutoff (at...

If I understand correctly, the Planck length, or maybe a tenth of it, is considered the point at which quantum effects mess up any attempt to apply our present physical laws, and so one could not even in theory make a dependable measurement of something smaller. However, I was wondering what...

This thread is prompted by a closed thread which left it’s OP’s original question unanswered. ->https://www.physicsforums.com/threads/average-wavelength-for-blackbody-radiation.423536/ The original question asked: is the ratio, of (a) the wavelength corresponding to the average energy in the...

If an object was traveling fast enough relative to an observer such that it's length is contracted down to the Planck scale (as with time), I would imagine that any further increase in speed would result in no more observable relativistic effects? Please correct me if I'm wrong.

Mods, I wasn't sure whether to put this in quantum physics or relativity, but since the speed of light is the limiting factor I chose here. Move wherever you think is best. Okay so the speed of light is the asymptote for the speed that objects can accelerate to, and the Planck time is the...

Does anyone know how I could convert data from Planck, which appear as an oval shape, into a form that I can easily map onto a sphere (ie. a rectangular shape in 2:1 aspect ratio)? Here is an example Planck image: http://sci.esa.int/science-e-media/img/61/Planck_CMB_Mollweide_4k.jpg I see that...

Hello, I was researching the Planck Constant values and decided to build a math software to scan for potential values that relate to permittivity of free space and permeability of free space and found one of the 2010 CODATA values (specifically the Magnetic Resonance Imaging value). Can I get...

Hello, I was watching watch videos lol. I bought a new automatic watch and I was interested to see how they work, here is a nice YouTube video; There are various types of watches / clocks. Sun dial, mechanical, kinetic, quartz and of course atomic. They all, however, measure time kinda...

Referring to LEDs as I'm not aware of any other "colour-producing" light, does blue light use more energy than red light? Planck's formula (E=hf) leads me to believe that blue light would drain a battery quicker than red, due to its higher frequency. Surely a device emitting blue light would...

What is the difference between these reduced Planck masses? ##M_p = \sqrt \frac{ħc}{8πG}~## and ##~M_p = \sqrt \frac{1}{8πG}## I see people use either, but what is the difference? It can't be that ħ and c are set to 1 because G is also a Planck unit and it would be nonsense to set a Planck...

from the formula M_p=\sqrt{\frac{\hbar c}{G} If gravity is weak.. Planck mass is huge. Does the formula assumes whether general relativity is classical limit of some quantum theory or whether general relativity needs quantization? Because the problem with the Hierarchy problem in the...

If gravity becomes stronger. would the Planck length becomes longer or bigger? Would speed of light c also have the same effect of changing the Planck length size? Would anyone know any java website that can make you adjust the strength of gravity and c and see how big or small the Planck scale...

I was wondering if it is possible to work out the maximum amount of energy an object with mass can have using the length contraction equation (i.e. "actual" length divided by Lorentz factor). The way I thought of doing this was by rearranging e = mc^2 to get c^2 = e/m. Then, substitute e/m into...

As far as I understand, phonons are just thermal vibrations of atoms in a lattice and blackbody radiation is just the radiation emittied due to thermal oscillations accelerating the atoms back and forth. Is there any example of a derivation of the Planck equation from considering black body...

Hello! Let's consider again a system of atoms with only two permitted energy levels E_1 and E_2 > E_1. When electrons decay from E_2 level to E_1, they generate a photon of energy E_{21} = E_2 - E_1 = h \nu. The number of photons (per unit frequency, per unit volume) emitted by such a system in...

Since ##c=1## we have ##[l]=[t]##, ##\hbar=1## and from Einstein law ##E=\hbar\omega\rightarrow [E]=[t^{-1}]##, ##G=1\rightarrow [E]=[m]^2[t^{-1}]## then we must have ##[m]=1## but since ##E=mc^2\rightarrow [E]=[t]^2## Can someone please point out my mistake

I know that if an object moves at the speed of light, from its persepctive time will stop to a halt. However the smallest unit of time should be the plank time. So my question is, will the object (say a photon) experience throughout its life a single still "frame", or will it experience...

Below Planck scale means inside the Planck scale, and above Planck scale means outside of Planck scale? If the term is correct.. why doesn't quantum gravity theory like Loop Quantum Gravity affect low energy experiments above the Planck scale (outside of Planck scale)? Quantum field theory is...

Hi. I was wondering if experiments on the Planck length (about 10-35 m) are possible or not. If it is possible, what kind of experiment would that be? If it's not, then what is the problem? Or what is need to be done? Thanks.

Hello, as a non-physicist enthusiast, but with decent math background, I tried to learn a bit about origins of quantum theory and very soon raised some questions, which I hope this community will answer. So, Planck tried to model the blackbody radiation on where Raighley and Jeans have failed...

This article is posted on twitter with the byline: "You, me, and even aliens from Alpha Centauri could arrive at the same Planck units." but does not explain why. http://www.symmetrymagazine.org/article/the-planck-scale I believe I have read (but cannot find the reference now) the following...

I was reading a paper by Starobinsky on spectrum of relict gravitational radiation. He uses the term Planck curvature as follows "We construct a model in which the universe was perpetually in the quantum state with the radius of curvature of the order of Planck curvature, and later left this...

This thread is about a topic that unexpectedly came up in my thread titled "Contradiction between Cosmos and what someone here told me?". I will subsequently call that thread "Contradiction" for brevity. I am not sure if this thread belongs on the Quantum Physics forum or the chemistry forum...

Is it proved experimentally that the Planck constant is invariant in the moving system? If that experiment exists, would you show me that in detail?

Why is Planck radiation the greatest amount of radiation that anybody at thermal equilibrium can emit from its surface, whatever its chemical composition or surface structure?

When we throw an object vertically , its speed decreases due to gravity and comes to a halt at the very top, V=0 and starts falling down. What can we say about that "halt" moment? Is it defined in terms of seconds? Does it last as long as Planck time? being the smallest measurement of time that...

I was watching this PBS Spacetime video, and something they said bugged me. They said that some subatomic interactions are occurring at time scales less than the Planck Time. And thus, this would also mean that these things are happening at scales less than the Planck Length as well. My...

Hi. Can we infer something about physics from stuff like Vitali sets or the Banach-Tarski paradox? Maybe if we assume the energy in a given space volume to be well defined and finite, that there must be fundamental particles that can't be split, or that there must be a Planck length and energy...