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How the Nobel Prize for Physics in 2019 depends on atomic physics and how lasers can be improved




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As I regularly state, I am an experimental atomic, molecular and optical physicist, meaning that this year's Nobel Prize in Physics for Cosmology and The Discovery of extrasolar planets is what I normally endure.I'm glad to leave detailed descriptions of what the three new winners in the capable hands of Ethan "Starts With A Bang" Seals have done, is an indirect connection to my field of research, which is one

The half Nobel Prize split by Michel Mayor and Didier Q ueloz "for the discovery of an e xoplanet orbiting a solar-type star" is based on the "radial velocity method" to detect planets in orbit around another star. This takes advantage of the fact that while stars are much larger than planets – the mass of the sun is millions of times the size of the earth's mass – they are not fixed in space. The gravitational force between a star and a planet affects both bodies equally, which means that they both move in response. The orbit of the planet is much more dramatic thanks to the smaller mass, but the star also traces an ellipse that is complementary to the orbit of the planet but much, much smaller.

This means that a orbiting exoplanet makes its home star. Wiggle lightly and give it a speed along our line of sight that changes as orbit progresses – first slightly towards us, then slightly away, then up again us and so on. If you can measure that speed, you can analyze it to extract all sorts of information about the size and shape of the orbit, the mass of the planet, and so on.

(There is another complementary method of detecting exoplanets, which is to look for the slight obscuration that occurs when a planet is placed between us and its star, which was not included in this Nobel Prize Basis of a future price.)

How do you measure this speed, considering that the stars are many light-years away and you can not make them glow with a radar? Well, you use the Doppler effect, a shift in the frequency of a wave that depends on the relative velocity of the source, which is the physics behind the "EEEEEEEEE-OWWWWWWWW" noise, even surprisingly small children Knowing that it's a fast-moving car: when a car moves toward you, engine noise is shifted to a higher pitch ("EEEEEE") and lower pitch when it drifts away (the "OWWWW"), and just as it happens, it quickly changes from one to another.

The same physics applies to light waves, but because the speed and frequency of the light are so much higher, the size of the displacement is G is far less obvious: for visible light with a wavelength of about 500 nanometers emitted by a star moving 1 meter per second (a not unreasonable standard for interesting planet-star combinations), the frequency change is about three Billionth of the frequency of light, compared with a shift of about 10% of the frequency of radiated sound waves A driving car.

How do you measure such a small layer? Very, very carefully – that's why it's worth a Nobel Prize. Atomic, molecular and optical physics also come into play here, because we make painstakingly accurate measurements of light frequencies.

There are two pieces you need for radial velocity measurement: First, you need to know the frequency of the light emitted by the star very well, and second, you need to know the frequency of the light that you use very much well know, know. In both cases, this depends on the quantum physics of the atoms: every atom in the periodic table absorbs and emits light at a discrete set of frequencies equal to the energy difference as electrons move between quantum states. This means that the light of a lamp, which contains a specific element and is fed into a spectrograph, creates a unique set of narrow, bright lines. Starlight with a wide frequency spectrum that passes through a gas sample is absorbed in narrow areas, which appear as dark absorption lines – essentially shadows – when fed into a spectrograph.

These spectral lines are like we Identify the composition of distant objects in the Universe by matching their emitted and absorbed light frequencies with those known from elements measured here on Earth. That's also what Mayor and Queloz (and many other people) used to determine the speed of distant stars: they found lines that could be identified with certain elements here on Earth, and watched them for tiny frequency shifts that coincided with changed the time. Again, the displacement they sought was tiny, but they could challenge them by following many lines. In the first article about their discovery, they said that they used about 5,000 different lines in the visible spectrum. Without the careful spectroscopic measurements that enabled the identification of all these lines, they would not have been able to do so.

There is also a contribution to the earthbound end, namely the need to know the frequency measured here, which is not quite as easy as taking photos of the spectrum night after night, since an astronomical spectrograph is one complicated instrument with many moving parts and can change slightly over time, in order to obtain good measurements, all runs must be carefully calibrated, generally by feeding light from a lamp of known composition and using the known frequencies of the spectral lines as a reference to check the frequency of the starlight of interest.

In the award-winning Mayor and Queloz measurements, this was done with lamps, but this calibration step is where lasers can improve things. The spectral lines of a lamp are distributed somewhat irregularly in the spectrum and can also shift slightly with changing lamp states. This limits the accuracy of the calibration that can be obtained, thereby limiting the speed change that can be detected.

This situation can be improved by submitting another Nobel Prize-winning discovery awarded to John L. Hall and Theodor W. Hänsch in 2005 for the development of optical frequency combs. A frequency comb is a pulsed laser system whose output is a "comb" of narrow lines covering a wide range of the spectrum and arranged at regular intervals. The frequency of these lines can be very directly bound to an atomic clock, giving them a degree of inherent stability that is not achieved by any lamp, thus becoming an ideal source of calibration.

Kamm ", and I've written about it here before. It is being watched at NIST in Munich and at the Harvard-Smithsonian Center for Astrophysics, among others. This leads to one of my favorite descriptions of a research program in the half-joke: Dave Phillips of Harvard-Smithsonian once said that her project had "tried to discover Venus". That is, they make observations of the sun as if they were a distant star, and in search of tiny velocity shifts that they know they must be there because there are planets we already know exist , This provides a wealth of information on factors other than radial-velocity Doppler shifts that affect this type of measurement, and develops tools that will help narrow down to more Earth-like planets over the coming years.

(There is also a potential application of this technique to the observation of dark matter, which may have a connection with the other half of this year's Nobel Prize, but that is a very different topic …)

Even if not Obviously, this year's Nobel Prize is indeed dependent on the quantum physics of atoms and molecules. And the field that kicked it off can also benefit from bringing lasers into the picture to make even more astonishing discoveries possible in the future.

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As I note here, I'm an Experimental Atomic Molecule That means that this year's Nobel Prize in Physics for Cosmology and the discovery of extrasolar planets is what I normally endure. detailed descriptions of what the three new winners have done Ethan's capable hands "begin with a bang" seal, however, there is an indirect connection to my area of ​​research that is worth a little explanation.

The one by Michel Mayor and Didier Queloz "for the discovery of an exoplanet that has a star from Sola rkreis encircled "divided half Nobel Prize is based on the" radial velocity method "to detect orbit in orbit another star. This takes advantage of the fact that while stars are much larger than planets – the mass of the sun is millions of times the size of the earth's mass – they are not fixed in space. The gravitational force between a star and a planet affects both bodies equally, which means that they both move in response. The orbit of the planet is much more dramatic thanks to the smaller mass, but the star also traces an ellipse that is complementary to the orbit of the planet but much, much smaller.

This means that a orbiting exoplanet makes its home star. Wiggle lightly and give it a speed along our line of sight that changes as orbit progresses – first slightly towards us, then slightly away, then up again us and so on. If you can measure that speed, you can analyze it to extract all sorts of information about the size and shape of the orbit, the mass of the planet, and so on.

(There is another complementary method of detecting exoplanets, which is to look for the slight obscuration that occurs when a planet is placed between us and its star, which was not included in this Nobel Prize Basis of a future price.)

How do you measure this speed, considering that the stars are many light-years away, so they can not be lit with a radar? Gun Well, you use the Doppler effect, a shift in the frequency of a wave that depends on the relative velocity of the source, which is the physics behind the "EEEEEEEEE-OWWWWWWWW" noise, which is surprisingly small Children know it's a fast-moving car: when a car moves toward you, engine noise is shifted to a higher pitch ("EEEEEE") and lower pitch when it drifts away (the "OWWWW") and just as it happens, it quickly changes from one to the other.

The same physics applies to light waves, but because the speed and frequency of the light are so much higher, the size of the However, for visible light with a wavelength of about 500 nanometers emitted by a star moving 1 meter per second (a not unreasonable standard for interesting planet-star combinations), the frequency change is about three Billionth of the frequency of light, compared with a shift of about 10% of the frequency of radiated sound waves A driving car.

How do you measure such a small layer? Very, very carefully – that's why it's worth a Nobel Prize. Atomic, molecular and optical physics also come into play here, because we are cruelly measuring the frequencies of light.

There are two pieces you need for radial velocity measurement: First, you need to know the frequency of the light emitted by the star very well, and second, you need to know the frequency of the light that you use very much well know, know. In both cases, this depends on the quantum physics of the atoms: every atom in the periodic table absorbs and emits light at a discrete set of frequencies equal to the energy difference as electrons move between quantum states. This means that the light of a lamp, which contains a specific element and is fed into a spectrograph, creates a unique set of narrow, bright lines. Starlight with a wide frequency spectrum that passes through a gas sample is absorbed in narrow areas, which appear as dark absorption lines – essentially shadows – when fed into a spectrograph.

These spectral lines are like we Identify the composition of distant objects in the Universe by matching their emitted and absorbed light frequencies with those known from elements measured here on Earth. That's also what Mayor and Queloz (and many other people) used to determine the speed of distant stars: they found lines that could be identified with certain elements here on Earth, and watched them for tiny frequency shifts that coincided with changed the time. Again, the displacement they sought was tiny, but they could challenge them by following many lines. In the first article about their discovery, they said that they used about 5,000 different lines in the visible spectrum. Without the careful spectroscopic measurements that enabled the identification of all these lines, they would not have been able to do so.

There is also a contribution to the earthbound end, namely the need to know the frequency measured here, which is not quite as easy as taking photos of the spectrum night after night, since an astronomical spectrograph is one complicated instrument with many moving parts and can change slightly over time, in order to obtain good measurements, all runs must be carefully calibrated, generally by feeding light from a lamp of known composition and using the known frequencies of the spectral lines as a reference to check the frequency of the starlight of interest.

In the award-winning Mayor and Queloz measurements, this was done with lamps, but this calibration step is where lasers can improve things. The spectral lines of a lamp are distributed somewhat irregularly in the spectrum and can also shift slightly with changing lamp states. This limits the accuracy of the calibration that can be obtained, whereby the speed change that can be detected has a lower limit.

This situation can be improved by submitting another Nobel Prize-winning discovery awarded to John L. Hall and Theodor W. Hänsch in 2005 for the development of optical frequency combs. A frequency comb is a pulsed laser system whose output is a "comb" of narrow lines covering a wide range of the spectrum and arranged at regular intervals. The frequency of these lines can be very directly bound to an atomic clock, giving them a degree of inherent stability that is not achieved by any lamp, thus becoming an ideal source of calibration.

Kamm ", and I've written about it here before. It is being watched at NIST in Munich and at the Harvard-Smithsonian Center for Astrophysics, among others. This leads to one of my favorite descriptions of a research program in the half-joke: Dave Phillips of Harvard-Smithsonian once said that her project had "tried to discover Venus". That is, they make observations of the sun as if they were a distant star, and in search of tiny velocity shifts that they know they must be there because there are planets we already know exist , This provides a wealth of information on factors other than radial-velocity Doppler shifts that affect this type of measurement, and develops tools that will help narrow down to more Earth-like planets over the coming years.

(There is also a potential application of this technique to the observation of dark matter, which may have a connection with the other half of this year's Nobel Prize, but that is a very different topic …)

Even if not Obviously, this year's Nobel Prize is indeed dependent on the quantum physics of atoms and molecules. And the field on which the starting signal was fired can also benefit from the fact that lasers are put into the picture to make even more astonishing discoveries possible in the future.


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