Recent content by James2018

Look at the rings of green laser light I got from using a beamsplitter only 9 mm in size and two mirrors to recombine the split laser beam! You can see the shadow of the cube beamsplitter in the middle of the concetric rings.

Ok it's 6.5 dollars not 5 dollars. Perhaps it's because it's available in a stock of 10,000 pcs every month and it's made of a cheap material - PET plastic?

Perhaps, but my 5$ plastic diffraction grating is labeled as "Professional". You can see this in the photo below on the package label:

This is how the combined pattern looks like for that dichroic filter and diffraction grating looks like in front of a white LED source:

What do you think of my dichroic mirror and diffraction grating? Diffraction grating 600 lines / mm, PET, 5.90$; dichroic mirror reflects cyan (~490 nm) and transmits red (~644 nm), 4.76 $, K9 glass. I think the transmitted color is best seen on a white background and the reflected color on a...

But I am speaking about how in the quantum world everything is in superposition,not definite fixed values like in the classical world. And a macroscopic arrow of time has no meaning. Cause and effect are meaningless for reversible changes. CPT symmetry. Are you saying time exists at the...

I found The interpretation Please explain it "The physically measurable manifestation of a negative atomic excitation time would be a change in the sign of thr pointer variable upon post-selecting on transmission of the photon. In particular, using the experimental setupd escribed in Sec. I...

I don't know how to interpret the experiment but also read this https://arxiv.org/abs/2310.00432 since it is a reference to the first article.

Maybe the photon has a coherence time,remember energy time Heisenberg uncertainty relation? The time of emission is uncertain. The uncertainty in lifetime of an excited state is related to the uncertainty in the energy of an excited state "Fast-decaying states have a broad linewidth, while...

I remember somewhere in a book on statistical mechanics saying about how laws of physics look the same observed in forward and reverse at microscopic scale but at the macroscopic scale with large ensembles of particles, the second law of thermodynamics sets up an arrow of time which does not...

Whatever this quote means? "In the case of the group delay, negative times can be understood as the result of the incident pulse being re-shaped by the atoms. In particular, the trailing half of the incident pulse experiences more absorption than thel eading half due to the finite response time...

There is no group velocity here, that is part of another older study by L.Wang Gain-assisted superluminal light propagation, where the wavepacket is compared to a "superluminal bus" and photons as passengers that enter the bus and leave but travel at the speed of light and never exceed it, only...

In a recent experiment published on 5 September 2024 by a physicist at the University of Toronto called Aephraim M. Steinberg and his team in a study called "Experimental evidence that a photon can spend a negative amount of time in an atom cloud", that involved shooting photons through a cloud...

If I place the AM radio 1 centimeter away from the inductor or from the antenna, the 700 KHz frequency goes completely silent. Otherwise, the noise reduces in intensity but not completely. The antenna does not have the right length to emit at a large distance. Half a meter away the noise...

Yes, at last! It's between 600 and 800, somewhere in between, see for yourself where the slider is: