Planck Definition and 381 Threads

So the discovery of gravitational waves observed a contraction and stretching of space-time, and I've been trying to understand how the expansion of the universe means that space itself is growing. I want to understand how this actually works in relation to 'things' like a photon and an atom...

Amount of Planck energy is 1.956 * 10^9 J. Was this total energy of universe at plank time at big bang cosmology model? It's clear this amount of energy is not enough for making our solar system, even it's not enough for making mass of me ( 60 kg ). Should we postulate energy increase in the...

Hello! I have a little trouble with understanding Planck's law of radiation, and wondered if you could help me with it. :) The equation is: ## \frac{dI}{d\lambda} = \frac{2\pi hc^2}{\lambda^5(e^{hc/\lambda kT}-1)} ## (1) where T is the temperature, k Boltzmann's constant, h Planck's constant...

When I was young I read Schrodinger's memoirs. I can't find a book, but I remember he described an interesting conversation with Max Planck about what to do during the political catastrophe. The conversation was in 1940, and Schrodinger was asking Planck's opinion on what to do - to immigrate...

I found this question here but i do not understand the answer. One equation is from classical physics and the other from quantum physics. Is there another way to go from classical to quantics than the analytical extension?

Hi all, According to quantum mechanics, the graviton is the measure of the smallest amount of curvature possible in space-time. I read that the mass which would be required to create this curvature is Planck Mass which is close to the value 10^-5g. But the elementary particles, like electrons...

I listened to a lecture the other day that some anomalies in observations compared to theory caused Max Plank to derive his famous Constant.

Wikipedia says: Traditional big bang cosmology predicts a gravitational singularity before this time, but this theory relies on general relativity and is expected to break down due to quantum effects. https://en.wikipedia.org/wiki/Chronology_of_the_universe Although I found other pages, I have...

What do we know or speculate as to the size of the visible and entire universe between the Planck time and the beginning of explosive inflation?

Nor sure if this has already been discussed. But recently Rovelli has suggested the mysterious Fast Radio Bursts might be from Planck Stars : https://www.gravity.physik.fau.de/events/tux3/rovelli.pdf Any thoughts? What are the other explanation and how can resolve this?

klotza submitted a new PF Insights post A Hand-Wavy Discussion of the Planck Length Continue reading the Original PF Insights Post.

Hello, I've a problem. I need to find the age of universe in normalized Planck units. In my case, I'm using Planck mass = 1 and: ##H = 1.18 × 10^{-61} \times t_P^{- 1}## With these values, how can I find the age of the universe? Thanks!

I get that Planck length is derived from h, G and c. But as a theoretical measure of length how is it affected or not affected by cosmological expansion?

Homework Statement I don't get how you can use x and p instead of delta x and p in Heisenberg's principle. Also why is it just h bar? Isn't it supposed to be h bar/2? Problem 2-iv Homework Equations delta x* delta p >= h bar/2 The Attempt at a Solution I tried to deal with this problem but I...

In today's Physics ArXiv: New constraints on primordial gravitational waves from Planck 2015. Authors Luca Pagano, Laura Salvati, and Alessandro Melchiorri of the Physics Department and INFN, Universita di Roma. Primordial gravitational waves from the universe exiting Inflation get more and...

Hello! So in looking at black hole thermodynamics, I came across the equation ## l_p = \sqrt{G\hbar} ## But in doing a dimensional analysis of ## \sqrt{G\hbar} ## I get ## [\sqrt{G \hbar}] = \sqrt{ \frac{Nm^2}{kg^2} \frac{m^3}{kgs} } ## This obviously doesn't amount to a length. What...

Homework Statement "Sometimes the idea of the quantum is compared to the units we use for money. A dollar can be divided into smaller units, where the cent is the smallest possible unit. How is this analogy incorrect? Homework Equations E=nhf The Attempt at a Solution My thought is that...

I read somewhere that you cannot tell the difference in position between a photon (Or any other particle) at some point in time and the same photon (Or other particle) less than a Planck time later, because it would not have traveled further than a Planck length, which apparently is the smallest...

What is the effect in quantum if Planck constant is zero? Here are some points that I could think of: if Planck constant is zero, the Heisenberg Uncertainty Principles will become zero, therefore either momentum or position of a particle can be known exactly. if Planck constant is zero, both...

Does anyone here ascribe any particular broader meaning to them? Is that they represent indivisible units a consensus of sorts? Do they have real meaning or are they a kind of trite observation?

I've been reading about black holes and dark matter and came across this theory: http://www.nature.com/nature/journal/v329/n6137/abs/329308a0.html where black holes don't completely evaporate, but evaporate until it hits an equilibrium where it's both unable to evaporate anymore (making it...

Hi, So I am a little confused on the Planck scale. Correct me if I'm wrong (I hope this doesn't sound idiotic) but I believe that any field on a classical scale should be able to be quantized and work on a quantum scale/Planck scale, where the Planck length and the Planck time are the...

Hi there, I am confusing on the statement that we have classical physics when Planck constant approaching zero. I search the similar topic in Physics Forums and I saw that most of the answers refer to the size effect. It argues that when we measure something in the scale of meter comparing to...

If you take the size of the observable universe can you find out how many cubic plank lengths can fit in the observable universe and it doesn't have to be exact just approximation.Also the math and formulas would be helpful too.

I'm reading Julian Barbour the end of time..I don't know if It's a good reading.. According to Planck unit of time (5.39121 × 10^−44 seconds), could the universe be said to have a "frame rate" and "snapshots" (as Julian Barbour mentions) could exist? (and, incidentally, Zeno's arrow paradox...

First time here, and looking for help on this. The 2nd part of this problem, I have seen some posts on and am still reviewing, but haven't found much on the 1st part. Homework Statement 1) Use l'Hopital's Rule to show that $${\lim_{\lambda\rightarrow 0^{+}}=0}\text{ and...

Rovelli & Vidotto's Planck Stars describes a possible quantum black hole - white hole transition through a quantum bounce somewhat analogous to the LQC bounce. In another thread, @marcus pointed out to me that this was not necessarilly considered the most likely scenario for a QG black hole. Is...

I am reading some of "Planck 2013 results. XXII. Constraints on inflation." The paper is full of values for various inflationary parameters under various models, with their confidence intervals. For instance, in Table 5 on page 13, the authors report that — for a model including both running of...

Markus or others who are familiar with this.. I am aware Fotini Markopoulou Geometrogenesis occurs only during the Big Bang. But I'd like to know if it's Planck scale structure a present (after the Big Bang) is similar to the Planck scale structure of Loop Quantum Gravity? If they were not...

A number of years ago , it was conjectured that space was finite and shaped like a dodecahedron. The claim was "data from the first year of the WMAP satellite – unveiled in February - agreed with the predictions of the standard big bang plus inflation model of cosmology for regions of space...

Homework Statement I'm trying to determine Planck's Constant through an experiment with the Photoelectric Effect, however, the equations I'm given and the data I've collected are not getting me to the 6.63e-34 that I need to be at. I'm graphing Stopping Potential (V) vs 1/λ and then using the...

I apologize in advance if this is not the correct place to post this. I am currently writing a paper in no-scale supergravity inflation, and now that the Planck 2015 results are here, it would be nice to use them to constrain the parameters of the model. I am in particular interested in the...

Hi. My nephew asked me a good question. I am trying to understand the Planck limit. It is said that we can not go lower than the Planck limit. But if we had a an imaginary powerful microscope to see at the plank level, and if we placed 2 Planck end to end with "half" a Planck sized length...

What do you guys think of Max Planck Institute for Physics as a place for one to pursue PhD in theoretical physics? ny previous experience you can share?

http://astrog80.astro.cf.ac.uk/Planck/Chromoscope/']I[/PLAIN] saw this referenced in a blog last week and thought it worthy of sharing. http://astrog80.astro.cf.ac.uk/Planck/Chromoscope/ It's built off of Chromoscope, an app for visualizing the sky in a range of wavelengths, but it uses...

The Planck 2015 (formerly 2014) Data Release will finally be released to the public tomorrow February 5. Details at- http://www.cosmos.esa.int/web/planck

In de Broglie's matter wave equation, a book(namely Concepts of Modern Physics) derived the matter wavelength by putting ##E=hf## and ##E=\gamma mc^2## as equals. However I thought that ##hf## was energy of a photon, not a particle. Aren't these two very different concepts?

This is not a homework problem, this is a question borne out of self-interest. I picked up the book "The Dreams that Stuff is Made of" by Stephen Hawking: (https://www.amazon.com/dp/0762434341/?tag=pfamazon01-20 ) and read the first article by Max Planck: "On the Distribution of Energy in the...

Questions Concerning The Planck Epoch I must begin this thread with an apology. I am NOT a physicist nor astronomer; in fact, my degree is in biology. However, for decades I have had a deep interest in what is commonly referred to as Big Bang Cosmology and have an “educated layman’s”...

Does anyone have any suggestions for finding lists of all papers published by individual physicists? Usually the Google machine turns up hits pretty quickly, but I've hit a brick wall looking for lists for Max Planck and Ludwig Boltzmann. netlib.org/bibnet/ is amazing, but it's pretty narrow.

I know what the letters mean, E = Energy of the photon, h = Planck's constant, f = frequency of the photon. But what does it mean for a particle to have a frequency, something that I'd associate with a wave. And what can you think Planck's constant is representing? Any replies would be much...

Does anyone know where I might find WMAP and/or Planck maps of the dipole/quadrupole/octupole images that were done using the cartesian cylindrical projection? I've been able to find them in the standard Mollweide projection via Google images but can't seem to find any that were made with the...

Hi. I wasn't sure where to post this, but wanted to share this amazing video. From the smallest to the biggest thing in the universe:

How can it be deduced general relativity from Planck length?

So far a lot of the stuff from the December Ferrara conference is in French. Nice movie! http://videotheque.cnrs.fr/visio=4401 Neutrino news: http://public.planck.fr/resultats/250-ce-que-planck-dit-des-neutrinos Latest on dark matter...

The ΛEPRL spin foam model presented 25 November at ILQGS by Haggard and Riello achieves an interesting quantization of the cosmological constant. Basically this is done on slide #10 around minute 15 of the audio. http://relativity.phys.lsu.edu/ilqgs/haggardriello112514.pdf...

I was reading a section of a chemistry textbook describing electron energy shells. It compares the electrons to light saying that electrons energies are quantized and so are light energies. Electrons can only jump from one specific energy level to another with no intermediary energy levels. I...

I see that Planck scale of mass-energy is related to the corresponding length scale by application of the uncertainty principle. What is not clear for me is how we find either energy or length scale to compute the other one? What goes wrong if we assume a higher energy level than the Planck...

I am having some issues with the derivation of the Planck Radiation Formula, as for instance given in http://hyperphysics.phy-astr.gsu.edu/hbase/mod6.html . My point is that the assumption of cavity modes implies the formation of standing waves inside the cavity walls. In most situations in...

Except for associating a statistical mean to a large number of measurements, how can one assign a single point to a particle ? Indeed, how can one assign a size of anything less than the Planck scale? A similar question about strings: how can one talk about one-dimensional objects? A similar...