# planck

1. ### B A question about the Planck Epoch

During the Planck Epoch was the universe in a pure state prior to the Grand unification epoch?
2. ### I Planck had 2 definitions of energy in 1900, how?

So, I was looking into Einstein's 1907 paper where he derived the specific heat of solids using quantum mechanics and I found that Einstein just took the derivative of Planck's equation from 1900 for the average energy, U, as a function of time (and multiplied it by 3N for the three dimensions)...

I am quite confused, as I start this question. I can easily find the following when searching up planck's law: However, this is not u. My prof is quite unclear and sometimes chooses his own variables as he sees fit, so i am not sure if this would be equivalent to what he is looking for u(λ)dλ...
4. ### Thermal Physics: Photon Statistics on Bose Particles

1. Homework Statement I have solve the rest of this problem pretty easily and see no problems with working with Indistinguishable particles, Distinguishable particles, fermions and Bosons. Part c has me very confused though about what it is even asking. Suppose a system with equally spaced...
5. ### A Planck 2015 CMB temperature individual pixel variance

Hi, I'm hoping someone can point me in the right direction please. I'm using the Planck 2015 CMB temperature (intensity) SMICA pipeline maps (Nside = 2048) and am trying to determine the temperature variance of each individual pixel. Variance and hit-count were provided with the 2013 CMB maps...
6. ### I The Planck units, just a fad?

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...
7. A

### B Planck-Einstein relation and the Photoelectric Effect

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...
8. ### B Why did Max Planck quantize light?

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...
9. ### B Thermal and Non thermal light emission

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,
10. ### I Converting Planck data for spherical projection

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...
11. ### I Blue lights (LEDs) consume more power than red (and green)?

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...
12. ### I Physical implications from Vitali sets or Banach-Tarski?

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...
13. ### Gravitational waves, distance and space-time

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...
14. ### Understanding Planck's law

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...
15. ### Heisenberg's Uncertainty

1. 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 2. Homework Equations delta x* delta p >= h bar/2 3. The Attempt at a Solution I tried to deal with this...
16. ### Primordial gravitational wave constraints from Planck 2015

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...
17. ### How Is This Quantum Analogy Incorrect?

1. 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? 2. Homework Equations E=nhf 3. The Attempt at a Solution My thought is...
18. ### Planck's Law vs Rayleigh-Jeans Law (Blackbody radiation)

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. 1. Homework Statement 1) Use l'Hopital's Rule to show that {\lim_{\lambda\rightarrow 0^{+}}=0}\text{ and...
19. ### Determining Planck's Constant With Photoelectric Effect

1. 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...
20. ### E=hf as energy of a particle (other than photon)

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?
21. ### Seeking bibliographies

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.
22. ### E=hf interpretation

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...
23. ### Photon energy

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...