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An experiment caught a quantum system in the middle of a jump — something the originators of quantum mechanics assumed was impossible.
When quantum mechanics was first developed a century ago as a theory for understanding the atomic-scale world, one of its key concepts was so radical, bold and counter-intuitive that it passed into popular language: the “quantum leap.” Purists might object that the common habit of applying this term to a big change misses the point that jumps between two quantum states are typically tiny, which is precisely why they weren’t noticed sooner. But the real point is that they’re sudden. So sudden, in fact, that many of the pioneers of quantum mechanics assumed they were instantaneous.
A new experiment shows that they aren’t. By making a kind of high-speed movie of a quantum leap, the work reveals that the process is as gradual as the melting of a snowman in the sun. “If we can measure a quantum jump fast and efficiently enough,” said Michel Devoret of Yale University, “it is actually a continuous process.” The study, which was led by Zlatko Minev, a graduate student in Devoret’s lab, was published on Monday in Nature. Already, colleagues are excited. “This is really a fantastic experiment,” said the physicist William Oliver of the Massachusetts Institute of Technology, who wasn’t involved in the work. “Really amazing.”
But there’s more. With their high-speed monitoring system, the researchers could spot when a quantum jump was about to appear, “catch” it halfway through, and reverse it, sending the system back to the state in which it started. In this way, what seemed to the quantum pioneers to be unavoidable randomness in the physical world is now shown to be amenable to control. We can take charge of the quantum.
Hidden beneath the expanding lobes of gas and dust in this multi-wavelength view is one of the most massive and volatile stars in the Milky Way. Eta Carinae was just another nondescript star until 1843, when it underwent a dramatic outburst and briefly became the second-brightest star in the night sky. It’s unclear exactly what prompted this explosive episode, but we do know that Eta Carinae – actually a double star system concealed at the epicentre of the two lobes – shed an enormous amount of mass from its outer layers in the process.
Hubble’s false-colour image combines visible light observations by its Wide Field Camera 3 with ultraviolet-light data from the its Ultraviolet Imaging Spectrograph. It shows the presence of gas – magnesium in blue, and shocked nitrogen gas presented here in red – that could have been ejected by the star shortly before its outburst, and which could therefore provide clues as to what caused the tumultuous eruption.
The large number of planned satellites have been met with criticism from the astronomical community.[115][116][117] Astronomers claim that the number of visible satellites will outnumber visible stars, and that their brightness in both optical and radio wavelengths will severely impact scientific observations.https://en.wikipedia.org/wiki/SpaceX_Starlink#Criticism
``Interference'' is the more general concept: it refers to the phenemenon of waves interacting. Waves will add constructively or destructively according to their phase difference. ``Diffraction'' usually refers to the spreading wave pattern from a finite-width aperture.
Two separate wave fronts originating from two coherent sources produce interference. Secondary wavelets originating from different parts of the same wave front constitute diffraction.
The region of minimum intensity is perfectly dark in interference. In diffraction they are not perfectly dark.
Width of the fringes is equal in interference. In diffraction they are never equal.
The intensity of all positions of maxima are of the same intensity in interference. In diffraction they do vary.
When we have two infinitely narrow slits separated by a distance apart near the source, we get interference. But when we have a single slit of finite width or rather an aperture near the source, we get diffraction.
The name interference itself gives it away. Two waves interfere or meet each other. When they do they cause an energy distribution which makes the famous bright and dark bands.
Diffraction refers to the fact that waves can bend around things. Diffraction of sound is so common, that you must have never thought about it. But since light is a wave, it diffracts too.
If you look at the two definitions, it would make one wonder, what’s the meaning of this question. The two phenomenon are so different and so nicely defined, why is there a confusion? Forget differences, what is even the similarity between the two?
Well the confusion is caused by a lot of teachers and books. It’s because of captions given to the images like these
Some are called as interference patterns, and some others are called as diffraction patterns. Which is absolutely non sense. So here is what is really going on.
In each picture, the light is made to pass through slit/s. When they do, the small opening makes the light diffract (bend around and spread out). So there is diffraction happening in all of these pictures. These waves, eventually meet each other and redistribute their energies, ergo, interfere with each other, which we can see as alternate dark and bright regions.
So all patterns (bright and dark regions) are caused by interference of light (by the very definition of it), and in all experiments when slits are used there is diffraction happening at each slit.
So it’s wrong to call something as interference or diffraction pattern. All are interference pattern itself.
Then we have something called the diffraction grating. It’s called so, because it has lots of slits, and so light undergoes lots of diffraction, but again, eventually the pattern is caused by interference of light.
Here is a CD. If someone asks what causes the colouration? If you say diffraction that’s wrong. The pits in the CD act like slits. So in that sense, its called a diffraction grating. But the coloration are caused by interference itself. Where you see Blue, it’s because the blue light is undergoing strong construction and rest, not so much. It’s not so different than the thin film interference, you see in oil spills and soap bubbles
So to summarise, all the energy distribution business, which causes coloration (in white light) or alternate dark and bright bands (in mono chromatic light) are called interference. Whenever waves spread out, or bend around a corner, it’s called diffraction. The two are worlds apart.
Two separate wave fronts originating from two coherent sources produce interference. Secondary wavelets originating from different parts of the same wave front constitute diffraction. Thus the two are entirely different in nature.
The region of minimum intensity is perfectly dark in interference. In diffraction they are not perfectly dark.
Width of the fringes is equal in interference. In diffraction they are never equal.
The intensity of all positions of maxima are of the same intensity in interference. In diffraction they do vary.
Feynman has come from heaven to answer your question! Listen to him:
No one has ever been able to define the difference between interference and diffraction satisfactorily. It is just a quest of usage, and there is no specific, important physical difference between them. The best we can do is, roughly speaking, is to say that when there are only a few sources, say two interference sources, then the result is usually called interference, but if there is a large number of them, it seems that the word diffraction is more often used.1
To be more explicit read this passage from Ajoy Ghatak:
We should point out that there is not much of a difference between the phenomenon of interference and diffraction, indeed, interference corresponds to the situation when we consider the superposition of waves coming out from a number of point sources and diffraction corresponds to the situation when we consider waves coming out from an area sources like a circular or rectangular aperture or even a large number of rectangular apertures (like the diffraction grating). 2
Credits: 1 Feynman Lectures on Physics 2Optics-Ajoy Ghatak.
Morality (from Latin: moralis, lit. 'manner, character, proper behavior') is the differentiation of intentions, decisions and actions between those that are distinguished as proper and those that are improper.[1] Morality can be a body of standards or principles derived from a code of conduct from a particular philosophy, religion or culture, or it can derive from a standard that a person believes should be universal.[2] Morality may also be specifically synonymous with "goodness" or "rightness".
Many other light sources, such as fluorescent lamps, or LEDs (light emitting diodes) emit light primarily by processes other than thermal radiation. This means that the emitted radiation does not follow the form of a black-body spectrum. These sources are assigned what is known as a correlated color temperature (CCT). CCT is the color temperature of a black-body radiator which to human color perception most closely matches the light from the lamp. Because such an approximation is not required for incandescent light, the CCT for an incandescent light is simply its unadjusted temperature, derived from comparison to a black-body radiator.
