I was about to ask if this was ai, but then I saw the watermark, that was enough to find the photographers and their site, it's real, and their stuff is amazing!
Here's a link to the original picture from Ray & Sue photography
Yeah lol. I actually didn't bother to measure or look up the true size of a banana, so I just estimated and figured it would be somewhere around that order of magnitude.
Atoms are surprisingly big imo. That's why we can see individual atoms using techniques like this, and also electron microscopy and atomic force microscopy.
What we see in the picture is the light emitted as a result of shooting the atom with lasers, so my guess is that that dot could be way bigger than the atom itself
I guess this is more of a piece of evidence that tiny particles really are a thing and scientists aren't just making it all up to troll us who don't know better. "The laser is bouncing off of something so atoms must be real"
Would that size be visible without a microscope, or is that bright dot resulting from shooting the atom with lasers actually way bigger than the atom itself?
The atom/ion is glowing. It's shooting off a lot of light in every direction and the researchers took a longer exposure photo. The apparent diameter of the atom is much larger than the physical size of the atom in this photo, because it is glowing so brightly.
You can see things smaller than the wavelength. You can't separate two things that are much closer than the wavelength and both glowing at the same time.
You’re right that atoms don't reflect light traditionally, but this strontium atom is being hit by lasers, causing it to absorb and re-emit photons. By using a long exposure, the physicist captured that emitted light, making a single building block of matter visible to the camera.
Absorbing and re-emitting photons is how all light-matter interactions like reflection and scattering work. In this case the strontium ion emitted light through resonance fluorescence. The frequency of the laser light was equal to the energy of an electronic transition im the strontium ion. Photon absorption excites an electron to a higher energy state and relaxation to the ground staye emits a photon of equal energy/frequency as the laser light.
Absorbing and re-emitting photons is how all light-matter interactions like reflection and scattering work.
You're out of luck, reflections and scattering do NOT involve any photon absorption or emission... Time to go back to the early chapters of the textbook ;-)
Absorption and re-emission would be fluorescence, and it's only a small part of the light-matter interactions.
If you wanna see a fancy non-linear optics phenomenon changing wavelength without absorption and re-emission, you can check second harmonic generation too. You could be interested in Raman scattering as well.
Raman scattering spectroscopy is my field of study.
The early chapters of the textbooks do not consider reflection and scattering as absorption, because they use the classical mechanics description. When using the quantum electrodynamics description, the interaction is generally described as absorption and re-emission of the photon with an intermediate virtual state.
I wouldn't say classical mechanics, just standard quantum mechanics considers scattering as the same photon going on... but ok for the rest, fair, I didn't think of that and apologize.
I don't like this terminology though haha, because absorption and re-emission behave so different from scattering, and we'd have to consider a photon propagating through a medium as being absorbed and re-emitted in several places at once constantly, sounds like a headache for a relatively simple thing, and more importantly it doesn't match the usage of these words in the other areas of physics and chemistry.
The only distinction between scattering and absorption/reemission is that during scattering the electron doesn't remain in an excited state for any significant length of time.
we'd have to consider a photon propagating through a medium as being absorbed and re-emitted in several places at once constantly
Yes. That's why light travels at different speeds in different mediums. It's the interference of the very many reemitted photons that causes an apparent slower EM propagation through a medium. Reflection(scattering) is also the result of the sum of very many reemitted photons interfering in a way that produces an identical reflection instead of a refraction or random reemission.
Edit:
I wouldn't say classical mechanics, just standard quantum mechanics
I'm not sure what you mean. I'm pretty sure they're referring to classical electrodynamics and not classical mechanics. Standard quantum mechanics treats photons interacting with matter as being governed by wave-particle duality. Those wave properties are what result in the very many reemitted photons being able to interfere with one another creating a directional reflection(scattering).
Those wave properties are what result in the very many reemitted photons being able to interfere with one another creating a directional reflection(scattering).
What I mean is the way I learned to deal with that in quantum physics is the same as you say calculation-wise (sum of spherical waves at every point of the scattering center), but considering all those spherical waves just density of presence. We sum up all these things, but we consider it the wavefunction of one photon, not the interference of an infinite number of photons.
This photon carries one quantum of energy and would be able to excite exactly one electronic transition downstream, which is why it makes sense to call it one photon rather than a pattern of interference between an infinity of reemitted photons. As you say, wave particle duality and all.
Yes. That's why light travels at different speeds in different mediums
We don't need a description in which photons are absorbed and reemitted to find that light travels slower in a medium, the simple wavefunction calculations based on scattering centers I described above gives this result...
What I mean is the way I learned to deal with that in quantum physics is the same as you say calculation-wise
The math agrees with me but rather than accept what the math is telling us about the physical reality you're hand-waving it away because you want to retain the concept of a photon having a continuous identity after it interacts with an electron which doesn't make physical sense. A photon can't be the same photon once it's interacted with something and changed it's momentum because changing it's momentum is changing it's identity. Photon's don't carry and conserve internal identifying states like that. We identify them by their position and their momentum. They aren't even things moving around. They're self-propagating excitations of a field not labelled billiard balls.
we consider it the wavefunction of one photon, not the interference of an infinite number of photons.
We don't? Quantum Mechanics tells us light takes infinitely many paths and that isn't a mathematical fiction. You can use polarized filters to disrupt the cancellation of phases of photons to show additional reflections from the same light source. Not to mention the double slit experiment demonstrates that photons self-interact even when they travel alone.
We don't need a description in which photons are absorbed and reemitted to find that light travels slower in a medium
It doesn't matter if we need it for that or not. It doesn't matter if a simpler model is easier to understand. It is what's causing changes in light's speed through different mediums. Just like gravity is caused by spacetime curvature even though we don't need to use anything more complicated than Newtonian gravity for most things.
This photon carries one quantum of energy
Did I suggest otherwise? Are you tracking a quanta of energy around or are you tracking a photon around? To me, tracking a quanta of energy makes even less sense than tracking a photon across interactions.
Edit:
would be able to excite exactly one electronic transition downstream
If we accept that the photon has an identity across interactions then it can interact with an infinite number of electrons. And what happens when a photon interacts with an atom and gets reemitted as two photons? Which photon is the original photon?
It doesn't matter if we need it for that or not. It doesn't matter if a simpler model is easier to understand. It is what's causing changes in light's speed through different mediums. Just like gravity is caused by spacetime curvature
You're confusing the rationale of a theory with reality. Virtual states that help a calculation are not real states. What's causing the change in speed through a medium is the longer path, even if you consider scattering to be a virtual absorption and reemission that part is instantaneous and the increased travel time is still the reason for the slower speed. Gravity is caused by spacetime curvature in the framework of general relativity. In other frameworks, that are more powerful than general relativity in some respects, it's caused by the Higgs boson or other things. In some frameworks photons are the excitation of a field, in others they are a particle with a wavefunction.
They're self-propagating excitations of a field not labelled billiard balls.
Wasn't it black body radiation that wasn't well explained by this purely wave-oriented view until Planck came along and introduced the concept of the billiard balls carrying a quantum of energy? And then Einstein and Compton, photoelectric effect and all? There were good reasons to introduce the first quantification and the wave particle duality. What I reproach to the way you put express things is the terminology you use for second quantification stuff is recycling words from first quantification stuff while altering their meaning, which puts a mess. Not saying it's just you or from you, but emission and scattering have very distinct meanings in all of chemistry and engineering physics, and this distinction is useful.
It's a bit like if I reused a word from Newtonian physics like kinetic energy and say now in my larger framework everything is kinetic energy, even the gravitational potential energy I'm gonna call it a kinetic energy, because I introduce these new virtual stuff that are useful to calculations.
To be fair the atom itself isn’t really visible it’s just the light from it is captured by the camera sensor, like how we don’t see lightning directly, we see the superheated plasma from the electrical field it produces in the air
To be fair, all matter in the universe isn’t really visible, it’s just that the light field of photons that’ve been inconvenienced by interacting with that matter interacts with the matter of our retinas to create sensory qualia that we interpret as things.
Except if something is blocking out a light source. Then you see the silhouette of the material because it blocks the light from behind—something you could never do with a single atom.
Which begs the question, how much larger than the atom is this orb of light being emitted? It's supposed to be a representation, but obviously that little atom is deep in the center of what we see as a tiny ball of light.
Well it says the photo was taken without a microscope, so the orb might be the size of a speck of dust, which is about a million times bigger than an atom
I was under the impression that absorbing and re-emitting is how objects are seen. But the guy above just said that's not possible because the atom is smaller than the wavelength.
That's the whole reason they use electron tunneling microscopes using electron beams that are small enough to interact with individual atoms. I'm trying to understand what he did differently that allowed him to just use light instead.
Electron tunneling microscopes are kinda more like “radar, but with electrons” because the image you get is an impression digitally produced by a computer. If you push your finger against a Lego for a minute and pull it back, the temporary impression in your skin is the final product.
This is just a regular photo. The little dot is a bunch of photons bouncing off the atom. The actual atom can’t be resolved and is much, much tinier than the dot. The camera however can capture these photons bouncing off of it, hence the dot.
To give a basic idea, you blast an object (an atom in this case) with a lot of high powered lasers. The photon (+ heat) collide with the atom. The atom, in its ground state, then absorbs this energy, which pushes an electron into a higher level shell. This is temporary. As the electron falls back into its original orbital (ground state), the energy is released as heat and light (photon).
Physically, it’s not the same way our eyes or camera traditionally resolve objects, but this is one method that is used to render very tiny particles observable.
Stuff absorb light when the energy per photon matches the difference of energy between a state that contains electrons and an empty state. Then the photon gets absorbed and an electron gets into an excited state.
Most often, we consider fluorophores and dyes which are at most around a nanometer in size and absorb light of 200 to 800 nm of wavelength, it's the normal rather than an exception.
For infrared and beyond, the same applies but it's gonna go into vibrations instead of electronic transitions.
we've been able to take them apart since 1938
we have had the knowledge of how to put them back together since 1960-something but i think we're still working on the machines to do the job
The picture I’m replying to is a camera image of laser light scattered off atoms. Optical light is insufficient for distinguishing atoms in a SOLID, because they are much closer than one wavelength, but that’s not at all what’s happening here. Maybe don’t say “nah” if you don’t even have a name for the “highly shielded equipment” you think might be involved (which you were possibly thinking of an AFM or STM).
It is an ion, which some people would not call an “atom” - to some the word atom means it has to be neutral. But if you permit this slight misuse of words, yes it is a strontium ion/atom. You’re introducing an confusing linguistic distinction that nobody else adheres to. One proton and one electron is called a “hydrogen atom”. Two protons, two neutrons, and two electrons is called a “helium atom”. So is a single atom of strontium called a strontium atom.
You can look at the spectrum of light given off. Depending on how many atoms you've got, you'll have resonant frequencies pop up corresponding to the motion of the atoms. More atoms, more motional modes, more resonant frequencies.
In fact, we can measure these frequencies precisely enough that we can tune lasers to these motional frequencies and slow down the atom. In other words, you can cool it using lasers.
Also, these are ions not atoms. Ions are charged atoms, and why we can trap them using electric fields.
Does someone have a link to help me understand how things like this are possible? For years I’ve read things about how scientists will blast a particle or a single atom, or smashing two particles together, or witnessing things at the subatomic scale, like, how do you obtain a single atom of something? How do you transport it within a container? How do you isolate a particle or a neutron within a device? I’ve seen a cloud chamber in action, but that’s individual particles being shed from a big piece, I get that much, but do you like, catch one?
A second physicist here (I work in atomic physics; not so different from this)… thankfully you’re majorly overthinking it. This is a completely different subfield of physics than particle accelerators. These are ions, not made in a particle accelerator - just coming from everyday matter all around us (although a fairly rare atom)
Originally, the strontium probably comes from an oven - basically a chamber has its walls coated in strontium, and it’s heated so that some evaporates out making some gas pressure of strontium throughout the experiment. Then, a laser with sufficient power and the right frequency can remove one electron from the strontium atom, making one (or more) charged strontium atoms. This laser is directed through something called a radiofrequency trap, which is a collection of oscillating and fixed electrodes which traps charged particles. So the created ions are now trapped. If you want only one, simply adjust the power of the ionization laser so that ionization is uncommon, and keep trying until you get one.
It's actually called an "Ion Trap" and the electrodes use a DC/RF to generate electric fields to suspend the ions. It's commonly used in Mass Spectrometers.
An RF trap is a quadrupole, the trap used in the picture is an ion trap. Two different things. I work on Mass Spectrometers, I know the difference lol. You just got your info from an article
I work in atomic physics. I did not get this from an article. I’m a bit closer to this than someone who uses a mass spectrometer.
Really, the fact that you’re insisting on using the more general term, and it sounds like you think an RF trap isn’t a type of ion trap makes it clear you don’t know what’s up. At least if you’re going to try to correct me, say what kind of ion trap you think it is. I’m saying “it’s a Highway”. You’re saying “it’s a road… totally different thing” (meanwhile I’m right… it’s a highway)
Go to the Wikipedia for the term you insist on using “ion trap”:
The two most popular ion traps are the Paul trap which uses static and oscillating electric fields[2] and the Penning trap, which uses a combination of static electric and also static magnetic fields to trap. Paul traps are often used when manipulating quantum states. They are used in trapped ion quantum computers[3] and realizing atomic clocks.
Of the two types, this is a Paul trap, which is also called a radiofrequency trap. No there is no requirement that it must be quadrupole to be called a radiofrequency trap.
Also see the wiki for “trapped ion quantum computer” which I believe is more exactly what this picture is of; specifically the section “Paul trap” (which doesn’t use the term radio-frequency trap explicitly; but does clearly describe this as specifically a paul trap, and not that it must be only called an ion trap)
I do! For reference, in case this doesn’t fully tickle your fancy, I looked up “atomic capture techniques”. This one uses ultra-cooling to trap ions.
I’m also a physicist and I’ve done research on photovoltaics (solar energy cells) using cool nanocrystals called quantum dots (lead sulfide quantum dot 3rd generation photovoltaics, the full name), which has a kind of similar mechanism to what they’re doing here with the strontium ion. Some of the stuff I was doing was manufacturing literal inks of the nanocrystals to deposit layers between 40nm-300nm (only hundreds to thousands of atoms thick) to create the solar cells.
That dot isn’t the atom’s size, it’s thr light it’s throwing off. The atom’s held in place with an electric field, blasted with lasers, and the glow is what the camera picks up.
That's exactly what it is in the pic/post. The next sentence, if you read it, explains why you can see it. It's pretty simple. Not sure what your point is....
The point, I'm guessing they are trying to make, is that the title could be misleading for any person who doesn't have a little knowledge about the topic.
It could easily be taken as that point is an atom but yes and no. No arrangement of lenses could be capable of seeing a single atom through visible light.
There should be many conditions to make something like what the photo is showing possible, at that point saying you're seeing an atom is misleading.we are seeing the effects of the lasers more than the atom itself.
It really is, though. If a 1000W light bulb is turned on 1 mile away, and you can physically see it, you would say you can see the light bulb. You can't actually see it because at that distance the bulb is too small to discern; you can only see the light from it. Anyone that you asked "Can you see the light bulb?" would say they could.
Sure but that’s just a matter of semantics, the light bulb itself would obviously be way too far away to actually see, you’d just be seeing the glow of light emanating from it but not the actual bulb. The glow is basically a blob of light, that’s what the speck is in the photo, technically from the atom but if you compared the size of the atom to the visible glow, it’s probably a million times smaller (which is about how a speck of dust compares to an atom’s size). It’s just intense enough that the photo sensor was able to pick up the light with a long exposure time, if you were able to zoom in on the photo data it would be just a bright pixel, which we can see with our naked eye.
So basically it’s a bright speck of light that becomes visible when exposed to a photo sensor, which then appears a million times larger than the actual source.
Another way to think of it is like how if a camera had a locked exposure and you took a picture of a laser shining into the lens, the entire photo would appear to be white as it maxed out the sensor, even though the laser is just a tiny source of light.
But in those cases you usually see the shape of the object. In this case we are seeing a bright dot that is way bigger than the atom itself. It would be like creating a car that emits a lot of light, putting it far away, then looking at it and seeing a big bright spot. It is a car technically, but that's not how we see most objects. I guess it's a matter of semantics
Just because it's a matter of semantics doesn't mean one of us isn't wrong.
It would be like creating a car that emits a lot of light
The headlight is what's making the light and the headlight is what you can see at a distance. If you're not seeing the headlight what are you seeing? Nothing? You're seeing photons coming from nothing?
I could say I'm only seeing the light, the glow coming from the object but not the object itself and still be correct. It depends on what one means with "seeing" in the end, that's why it's semantics
In that case you never see any physical objects and only see light. It would be equally true to say you can't see your couch as it is to say you can't see this atom.
(I work in atomic physics, not on radiofrequency traps like this, but related enough that I know exactly what this is)
In this kind of trap, people routinely trap multiple ions (these are ions not neutral atoms), and because of the repulsion between like charges, the ions are far enough apart that you can resolve not one, but multiple dots on the camera. In other words, they know it’s one ion because there’s one dot.
Yeah, this is an important point. With a better microscope, the "apparent size" of the atom would shrink. And ultimately, because atoms are much smaller than the wavelength of light, even with the best possible magnifying you still wouldn't see its "true" structure or size.
In a trap like this, the atoms will repel each other and spread out enough that you can just see them as multiple blobs. Here's an example from another research group of what that looks like.
I would not have described atoms as spheres at all… nor does this picture suggest that atoms are spheres. But if you have a point-like source of light and you take a picture of it, as long as your camera lens isn’t super wonky it will look roughly round.
It looks like a sphere to me... If you're more educated about this than I am - which is probably true, I haven't touched physics since high school - what shape would an atom even have, then? Are they square or something?
That's a genuine question if you do know the answer because I would actually really like to know.
For atoms as big as stratum, they hey are kinda of like spheres. Atoms are surrounded by an electron wave cloud. The electron wave is a standing wave that sloshes near the atom.
The wave cloud represents the probability that an electron will be found at a location when its time to measure.
It is pretty complex and mind bending to understand. I don't even understand all of it. Here is site that shows what the hydrogen atom electron waves looks like in 3d.
Every particle we see has a associated field. So the electron has a electron field. The amplitude of the electron field at any point is associated with the probability a electron will be observed there. This wave-function to probability is a weird fact of quantum physics. It means the wave can slosh over barriers or interact with itself and the electron will tunnel or interact with itself(even when there is one electron).
We only see the electron when measuring it, when not measuring the electron field evolves according to quantum equations. The electron wave in a atom hovers and sloshes around a atom.
You're actually seeing the electron cloud around the strontium nucleus glowing, which is much much larger than the actual nucleus. It is also a zoomed-in long exposure photo. IRL you probably could not see it due to the low intensity of emitted light.
Yes if this atom was next to other atoms as closely packed as in a solid, you wouldn’t be able to resolve it from the other atoms around. But there is only one ion trapped in this radiofrequency trap. This atom is the only thing that strongly scatters light from a laser pointed through the trap, so it acts as a single point source of light. It’s exactly the same as how you can see a star although the star is too small for you to resolve the size of the star with your eyes.
banana for scale?
The diameter of a strontium ion is about 100 picometers (10-10 meters). A banana is about 1 decimeter (10-1 meters).
Therefore, it's about 1 billionth of the length of a banana.
Wow this guy knows his bananas
https://preview.redd.it/w5ow8hxs8h8g1.jpeg?width=1024&format=pjpg&auto=webp&s=b33d65151506360de75b501ae1ce31da601b013a
I was about to ask if this was ai, but then I saw the watermark, that was enough to find the photographers and their site, it's real, and their stuff is amazing!
Here's a link to the original picture from Ray & Sue photography
https://www.travelandwildlifephotography.com/orangutans-camp-leakey/
But how does the thousandth banana kill you?!?
Potassium never sleeps.
K
😂
How sure are you? Have you seen his bananas?
Rick of spades I’d guess
1 nanobanana
a "bananano" if you will
Piconana
Nanonanner
ba deeee bi deepee
So if 1 strontium ion was 1 dollar, Elon musk would have 700 bananas as of today. Like who even has 700 bananas bro.
Edit: If I found out a friend had 700 bananas I would honestly be worried about them. That's far too many bananas.
There's always money in the banana stand
Unless your friend is Donkey Kong?
That is one small banana at a decimeter.
Yeah lol. I actually didn't bother to measure or look up the true size of a banana, so I just estimated and figured it would be somewhere around that order of magnitude.
You obviously haven't seen that recent post of a woman's forearm and banana...
what kind of banana..?
Wait, is strontium just that big? That feels like that's too few strontium ions in a line for a banana unit. Huh.
Atoms are surprisingly big imo. That's why we can see individual atoms using techniques like this, and also electron microscopy and atomic force microscopy.
https://preview.redd.it/r7kkw5qvbk8g1.jpeg?width=1800&format=pjpg&auto=webp&s=6a6ac80361eeaa2bf4d3018b85211be88242eea3
Cavendish, Gros Michel, or Lady Finger?
those are all pretty good potential band names
Depends on the size of the banana, but I trust your math
About how many refrigerators is that?
I feel like a microscope was still necessary
What we see in the picture is the light emitted as a result of shooting the atom with lasers, so my guess is that that dot could be way bigger than the atom itself
I guess this is more of a piece of evidence that tiny particles really are a thing and scientists aren't just making it all up to troll us who don't know better. "The laser is bouncing off of something so atoms must be real"
Where do you get bananas so small they’re only 1 decimeter?
Don't bananashame
This guy bananas
Would that size be visible without a microscope, or is that bright dot resulting from shooting the atom with lasers actually way bigger than the atom itself?
The atom/ion is glowing. It's shooting off a lot of light in every direction and the researchers took a longer exposure photo. The apparent diameter of the atom is much larger than the physical size of the atom in this photo, because it is glowing so brightly.
If you love bananas so much, why don't you marry one?
Damn it beat me to it...
Not needed. We can just call The Police and ask them directly.
Penis for scale?
Well you can't see an atom with a microscope anyway because it is smaller than light wavelength. Hence all this.
You can see things smaller than the wavelength. You can't separate two things that are much closer than the wavelength and both glowing at the same time.
You’re right that atoms don't reflect light traditionally, but this strontium atom is being hit by lasers, causing it to absorb and re-emit photons. By using a long exposure, the physicist captured that emitted light, making a single building block of matter visible to the camera.
Absorbing and re-emitting photons is how all light-matter interactions like reflection and scattering work. In this case the strontium ion emitted light through resonance fluorescence. The frequency of the laser light was equal to the energy of an electronic transition im the strontium ion. Photon absorption excites an electron to a higher energy state and relaxation to the ground staye emits a photon of equal energy/frequency as the laser light.
You're out of luck, reflections and scattering do NOT involve any photon absorption or emission... Time to go back to the early chapters of the textbook ;-)
Absorption and re-emission would be fluorescence, and it's only a small part of the light-matter interactions.
If you wanna see a fancy non-linear optics phenomenon changing wavelength without absorption and re-emission, you can check second harmonic generation too. You could be interested in Raman scattering as well.
Raman scattering spectroscopy is my field of study.
The early chapters of the textbooks do not consider reflection and scattering as absorption, because they use the classical mechanics description. When using the quantum electrodynamics description, the interaction is generally described as absorption and re-emission of the photon with an intermediate virtual state.
I wouldn't say classical mechanics, just standard quantum mechanics considers scattering as the same photon going on... but ok for the rest, fair, I didn't think of that and apologize.
I don't like this terminology though haha, because absorption and re-emission behave so different from scattering, and we'd have to consider a photon propagating through a medium as being absorbed and re-emitted in several places at once constantly, sounds like a headache for a relatively simple thing, and more importantly it doesn't match the usage of these words in the other areas of physics and chemistry.
¯_(ツ)_/¯
Egh. All models are wrong; some are useful. Ultimately, it's arbitrary.
Eh, not so much arbitrary as there’s still more to light we really don’t understand, and I say this as an optical engineer.
Also, username checks out.
Trying to follow along with you two is actually impossible as a layman, as it turns out, but I tried anyway.
But you're both clearly really smart and that's impressive, so have the compliment instead of awards. :p
I concur
The only distinction between scattering and absorption/reemission is that during scattering the electron doesn't remain in an excited state for any significant length of time.
Yes. That's why light travels at different speeds in different mediums. It's the interference of the very many reemitted photons that causes an apparent slower EM propagation through a medium. Reflection(scattering) is also the result of the sum of very many reemitted photons interfering in a way that produces an identical reflection instead of a refraction or random reemission.
Edit:
I'm not sure what you mean. I'm pretty sure they're referring to classical electrodynamics and not classical mechanics. Standard quantum mechanics treats photons interacting with matter as being governed by wave-particle duality. Those wave properties are what result in the very many reemitted photons being able to interfere with one another creating a directional reflection(scattering).
What I mean is the way I learned to deal with that in quantum physics is the same as you say calculation-wise (sum of spherical waves at every point of the scattering center), but considering all those spherical waves just density of presence. We sum up all these things, but we consider it the wavefunction of one photon, not the interference of an infinite number of photons.
This photon carries one quantum of energy and would be able to excite exactly one electronic transition downstream, which is why it makes sense to call it one photon rather than a pattern of interference between an infinity of reemitted photons. As you say, wave particle duality and all.
We don't need a description in which photons are absorbed and reemitted to find that light travels slower in a medium, the simple wavefunction calculations based on scattering centers I described above gives this result...
The math agrees with me but rather than accept what the math is telling us about the physical reality you're hand-waving it away because you want to retain the concept of a photon having a continuous identity after it interacts with an electron which doesn't make physical sense. A photon can't be the same photon once it's interacted with something and changed it's momentum because changing it's momentum is changing it's identity. Photon's don't carry and conserve internal identifying states like that. We identify them by their position and their momentum. They aren't even things moving around. They're self-propagating excitations of a field not labelled billiard balls.
We don't? Quantum Mechanics tells us light takes infinitely many paths and that isn't a mathematical fiction. You can use polarized filters to disrupt the cancellation of phases of photons to show additional reflections from the same light source. Not to mention the double slit experiment demonstrates that photons self-interact even when they travel alone.
It doesn't matter if we need it for that or not. It doesn't matter if a simpler model is easier to understand. It is what's causing changes in light's speed through different mediums. Just like gravity is caused by spacetime curvature even though we don't need to use anything more complicated than Newtonian gravity for most things.
Did I suggest otherwise? Are you tracking a quanta of energy around or are you tracking a photon around? To me, tracking a quanta of energy makes even less sense than tracking a photon across interactions.
Edit:
If we accept that the photon has an identity across interactions then it can interact with an infinite number of electrons. And what happens when a photon interacts with an atom and gets reemitted as two photons? Which photon is the original photon?
You're confusing the rationale of a theory with reality. Virtual states that help a calculation are not real states. What's causing the change in speed through a medium is the longer path, even if you consider scattering to be a virtual absorption and reemission that part is instantaneous and the increased travel time is still the reason for the slower speed. Gravity is caused by spacetime curvature in the framework of general relativity. In other frameworks, that are more powerful than general relativity in some respects, it's caused by the Higgs boson or other things. In some frameworks photons are the excitation of a field, in others they are a particle with a wavefunction.
Wasn't it black body radiation that wasn't well explained by this purely wave-oriented view until Planck came along and introduced the concept of the billiard balls carrying a quantum of energy? And then Einstein and Compton, photoelectric effect and all? There were good reasons to introduce the first quantification and the wave particle duality. What I reproach to the way you put express things is the terminology you use for second quantification stuff is recycling words from first quantification stuff while altering their meaning, which puts a mess. Not saying it's just you or from you, but emission and scattering have very distinct meanings in all of chemistry and engineering physics, and this distinction is useful.
It's a bit like if I reused a word from Newtonian physics like kinetic energy and say now in my larger framework everything is kinetic energy, even the gravitational potential energy I'm gonna call it a kinetic energy, because I introduce these new virtual stuff that are useful to calculations.
To be fair the atom itself isn’t really visible it’s just the light from it is captured by the camera sensor, like how we don’t see lightning directly, we see the superheated plasma from the electrical field it produces in the air
To be fair, all matter in the universe isn’t really visible, it’s just that the light field of photons that’ve been inconvenienced by interacting with that matter interacts with the matter of our retinas to create sensory qualia that we interpret as things.
Except if something is blocking out a light source. Then you see the silhouette of the material because it blocks the light from behind—something you could never do with a single atom.
Which begs the question, how much larger than the atom is this orb of light being emitted? It's supposed to be a representation, but obviously that little atom is deep in the center of what we see as a tiny ball of light.
Well it says the photo was taken without a microscope, so the orb might be the size of a speck of dust, which is about a million times bigger than an atom
Not all microscopes use light.
Not true, ever heard of scanning tunneling microscopy? IBM made a video called “a boy and his atom”using this technique.
How is it absorbing the light if it's smaller than the lights wavelength?
It’s absorbing a photon and re-emitting it via electron excitation. It doesn’t have to be as physically large as the wavelength.
I was under the impression that absorbing and re-emitting is how objects are seen. But the guy above just said that's not possible because the atom is smaller than the wavelength.
That's the whole reason they use electron tunneling microscopes using electron beams that are small enough to interact with individual atoms. I'm trying to understand what he did differently that allowed him to just use light instead.
Electron tunneling microscopes are kinda more like “radar, but with electrons” because the image you get is an impression digitally produced by a computer. If you push your finger against a Lego for a minute and pull it back, the temporary impression in your skin is the final product.
This is just a regular photo. The little dot is a bunch of photons bouncing off the atom. The actual atom can’t be resolved and is much, much tinier than the dot. The camera however can capture these photons bouncing off of it, hence the dot.
To give a basic idea, you blast an object (an atom in this case) with a lot of high powered lasers. The photon (+ heat) collide with the atom. The atom, in its ground state, then absorbs this energy, which pushes an electron into a higher level shell. This is temporary. As the electron falls back into its original orbital (ground state), the energy is released as heat and light (photon).
Physically, it’s not the same way our eyes or camera traditionally resolve objects, but this is one method that is used to render very tiny particles observable.
Stuff absorb light when the energy per photon matches the difference of energy between a state that contains electrons and an empty state. Then the photon gets absorbed and an electron gets into an excited state.
Most often, we consider fluorophores and dyes which are at most around a nanometer in size and absorb light of 200 to 800 nm of wavelength, it's the normal rather than an exception.
For infrared and beyond, the same applies but it's gonna go into vibrations instead of electronic transitions.
Thank you. Being physically smaller than wavelength does not mean invisible or that light passes through.
Different lights have different wavelengths not sure if thats the case here though
Your microwave has a wavelength of 4 inches. You can heat food that is less than 4 inches long.
You actually see tons of atoms all the time, technically
::clasps and parts hands dramatically::
Every time you see something you're seeing atoms.
Not quite correct sir.
Read up on why
My question is, how do you know it’s just one atom?
Scientists are able to separate atoms and hold them in suspension as individuals. They’ve been able to do this for not too long now.
How long 'til we can take them apart and put them back together? Non-explosively, I mean.
we've been able to take them apart since 1938
we have had the knowledge of how to put them back together since 1960-something but i think we're still working on the machines to do the job
When you say non-explosively, what do you mean?
If you mean without releasing energy, i think the answer is never. I could be wrong though.
If you mean without it turning into an explosion, then the answer is now.
The atoms repel each other and spread out. Here's an example of a similar trap, at higher magnification.
https://preview.redd.it/rhwascl99i8g1.jpeg?width=320&format=pjpg&auto=webp&s=d06fff2966e6b279bc66f73227d3dc4b98cdc499
In other words. The atoms are far enough apart in this kind of experiment to resolve them. We know it’s one because there’s one dot.
Nah optical isn’t enough to resolve individual atoms, they use sensitive highly shielded equipment to detect them I believe
The picture I’m replying to is a camera image of laser light scattered off atoms. Optical light is insufficient for distinguishing atoms in a SOLID, because they are much closer than one wavelength, but that’s not at all what’s happening here. Maybe don’t say “nah” if you don’t even have a name for the “highly shielded equipment” you think might be involved (which you were possibly thinking of an AFM or STM).
Snobbiness doesn’t look good on you, fyi I wasn’t talking about THIS specific situation
Then is it really a strontium atom, or is it just an atom that was once apart of other atoms that were once strontium?
It is an ion, which some people would not call an “atom” - to some the word atom means it has to be neutral. But if you permit this slight misuse of words, yes it is a strontium ion/atom. You’re introducing an confusing linguistic distinction that nobody else adheres to. One proton and one electron is called a “hydrogen atom”. Two protons, two neutrons, and two electrons is called a “helium atom”. So is a single atom of strontium called a strontium atom.
Science!
You can look at the spectrum of light given off. Depending on how many atoms you've got, you'll have resonant frequencies pop up corresponding to the motion of the atoms. More atoms, more motional modes, more resonant frequencies.
In fact, we can measure these frequencies precisely enough that we can tune lasers to these motional frequencies and slow down the atom. In other words, you can cool it using lasers.
Also, these are ions not atoms. Ions are charged atoms, and why we can trap them using electric fields.
Does someone have a link to help me understand how things like this are possible? For years I’ve read things about how scientists will blast a particle or a single atom, or smashing two particles together, or witnessing things at the subatomic scale, like, how do you obtain a single atom of something? How do you transport it within a container? How do you isolate a particle or a neutron within a device? I’ve seen a cloud chamber in action, but that’s individual particles being shed from a big piece, I get that much, but do you like, catch one?
A second physicist here (I work in atomic physics; not so different from this)… thankfully you’re majorly overthinking it. This is a completely different subfield of physics than particle accelerators. These are ions, not made in a particle accelerator - just coming from everyday matter all around us (although a fairly rare atom)
Originally, the strontium probably comes from an oven - basically a chamber has its walls coated in strontium, and it’s heated so that some evaporates out making some gas pressure of strontium throughout the experiment. Then, a laser with sufficient power and the right frequency can remove one electron from the strontium atom, making one (or more) charged strontium atoms. This laser is directed through something called a radiofrequency trap, which is a collection of oscillating and fixed electrodes which traps charged particles. So the created ions are now trapped. If you want only one, simply adjust the power of the ionization laser so that ionization is uncommon, and keep trying until you get one.
It's actually called an "Ion Trap" and the electrodes use a DC/RF to generate electric fields to suspend the ions. It's commonly used in Mass Spectrometers.
Seriously…. A radiofrequency trap (also called a Paul trap) is a kind of ion trap.
An RF trap is a quadrupole, the trap used in the picture is an ion trap. Two different things. I work on Mass Spectrometers, I know the difference lol. You just got your info from an article
I work in atomic physics. I did not get this from an article. I’m a bit closer to this than someone who uses a mass spectrometer.
Really, the fact that you’re insisting on using the more general term, and it sounds like you think an RF trap isn’t a type of ion trap makes it clear you don’t know what’s up. At least if you’re going to try to correct me, say what kind of ion trap you think it is. I’m saying “it’s a Highway”. You’re saying “it’s a road… totally different thing” (meanwhile I’m right… it’s a highway)
Go to the Wikipedia for the term you insist on using “ion trap”:
The two most popular ion traps are the Paul trap which uses static and oscillating electric fields[2] and the Penning trap, which uses a combination of static electric and also static magnetic fields to trap. Paul traps are often used when manipulating quantum states. They are used in trapped ion quantum computers[3] and realizing atomic clocks.
Of the two types, this is a Paul trap, which is also called a radiofrequency trap. No there is no requirement that it must be quadrupole to be called a radiofrequency trap.
Also see the wiki for “trapped ion quantum computer” which I believe is more exactly what this picture is of; specifically the section “Paul trap” (which doesn’t use the term radio-frequency trap explicitly; but does clearly describe this as specifically a paul trap, and not that it must be only called an ion trap)
I do! For reference, in case this doesn’t fully tickle your fancy, I looked up “atomic capture techniques”. This one uses ultra-cooling to trap ions.
I’m also a physicist and I’ve done research on photovoltaics (solar energy cells) using cool nanocrystals called quantum dots (lead sulfide quantum dot 3rd generation photovoltaics, the full name), which has a kind of similar mechanism to what they’re doing here with the strontium ion. Some of the stuff I was doing was manufacturing literal inks of the nanocrystals to deposit layers between 40nm-300nm (only hundreds to thousands of atoms thick) to create the solar cells.
That dot isn’t the atom’s size, it’s thr light it’s throwing off. The atom’s held in place with an electric field, blasted with lasers, and the glow is what the camera picks up.
You mean it's exactly what the title says?
The title explains the setup. I was just pointing out what that dot actually is, since a lot of people think it’s the atom’s size.
It's pretty well explained in the title. It's a single atom releasing a ton of light.
The title says "photo showing a single atom"
That's exactly what it is in the pic/post. The next sentence, if you read it, explains why you can see it. It's pretty simple. Not sure what your point is....
The point, I'm guessing they are trying to make, is that the title could be misleading for any person who doesn't have a little knowledge about the topic.
It could easily be taken as that point is an atom but yes and no. No arrangement of lenses could be capable of seeing a single atom through visible light.
There should be many conditions to make something like what the photo is showing possible, at that point saying you're seeing an atom is misleading.we are seeing the effects of the lasers more than the atom itself.
They’re making a good point that the atom itself isn’t actually visible
It really is, though. If a 1000W light bulb is turned on 1 mile away, and you can physically see it, you would say you can see the light bulb. You can't actually see it because at that distance the bulb is too small to discern; you can only see the light from it. Anyone that you asked "Can you see the light bulb?" would say they could.
Sure but that’s just a matter of semantics, the light bulb itself would obviously be way too far away to actually see, you’d just be seeing the glow of light emanating from it but not the actual bulb. The glow is basically a blob of light, that’s what the speck is in the photo, technically from the atom but if you compared the size of the atom to the visible glow, it’s probably a million times smaller (which is about how a speck of dust compares to an atom’s size). It’s just intense enough that the photo sensor was able to pick up the light with a long exposure time, if you were able to zoom in on the photo data it would be just a bright pixel, which we can see with our naked eye.
So basically it’s a bright speck of light that becomes visible when exposed to a photo sensor, which then appears a million times larger than the actual source.
Another way to think of it is like how if a camera had a locked exposure and you took a picture of a laser shining into the lens, the entire photo would appear to be white as it maxed out the sensor, even though the laser is just a tiny source of light.
Are you sure you want to spend writing long paragraphs on reddit fighting with people instead of doing something more productive?
Yeah, the title says it’s glowing, I’m just pointing out that the dot isn’t the atom itself. Sorry friend, if there's any kind of misunderstanding.
If the dot isn't the atom what is it? The light emitted by the atom?
The light emitted by an object is what we see when we see an object.
But in those cases you usually see the shape of the object. In this case we are seeing a bright dot that is way bigger than the atom itself. It would be like creating a car that emits a lot of light, putting it far away, then looking at it and seeing a big bright spot. It is a car technically, but that's not how we see most objects. I guess it's a matter of semantics
Just because it's a matter of semantics doesn't mean one of us isn't wrong.
The headlight is what's making the light and the headlight is what you can see at a distance. If you're not seeing the headlight what are you seeing? Nothing? You're seeing photons coming from nothing?
I could say I'm only seeing the light, the glow coming from the object but not the object itself and still be correct. It depends on what one means with "seeing" in the end, that's why it's semantics
In that case you never see any physical objects and only see light. It would be equally true to say you can't see your couch as it is to say you can't see this atom.
how do you know how much the light weighs that it’s emitting
THIS !
NOW, THE QUESTION IS HOW THEY KNOW IT'S EXACTLY 1 ATOM?
(I work in atomic physics, not on radiofrequency traps like this, but related enough that I know exactly what this is)
In this kind of trap, people routinely trap multiple ions (these are ions not neutral atoms), and because of the repulsion between like charges, the ions are far enough apart that you can resolve not one, but multiple dots on the camera. In other words, they know it’s one ion because there’s one dot.
OH, THAT MAKES SENSE. THANK U !
The elaboration in the comment above yours was helpful for me.
I think they were just explaining, for anyone who didnt understand it already, that the atom is a lot smaller than the light you see in the image.
Yeah, this is an important point. With a better microscope, the "apparent size" of the atom would shrink. And ultimately, because atoms are much smaller than the wavelength of light, even with the best possible magnifying you still wouldn't see its "true" structure or size.
Worth pointing out that this is just a part of the original photo. You can see the full thing here:
https://www.nationalgeographic.com/science/article/trapped-atom-photograph-long-exposure-competition-spd
It's nice because you can see some of the wires and screws in the trap, which give a sense of the scale.
You’re Great!
Could someone make a true scale comparison? Like if what we see in the picture is the size of a car, how big is the atom?
Would have to know what the scale of the image is to begin with, but my guess is millions of times smaller
More interested in how they can prove it’s a single atom and not multiple
In a trap like this, the atoms will repel each other and spread out enough that you can just see them as multiple blobs. Here's an example from another research group of what that looks like.
https://preview.redd.it/24jsw3919i8g1.jpeg?width=320&format=pjpg&auto=webp&s=344818abb8136ef83aae2d856718be1841951df3
Thank you!
You promise strontium, but all I can see are photons! Just kidding, it's amazing.
Amazing stuff
it was really me that took this photo I just didn't feel like posting it so yeah
I had no idea what a lot of that means but that’s pretty freaking cool
Reality is so bizarre.
How do we even single out atoms guh
The whos living in whoville on that atom.
How do you get the atom in there though and make sure it's not 2 atoms?
Honestly if anything it fucks me up that they are in fact spheres like the diagrams. Everything really is just a sphere huh!!
I would not have described atoms as spheres at all… nor does this picture suggest that atoms are spheres. But if you have a point-like source of light and you take a picture of it, as long as your camera lens isn’t super wonky it will look roughly round.
It looks like a sphere to me... If you're more educated about this than I am - which is probably true, I haven't touched physics since high school - what shape would an atom even have, then? Are they square or something?
That's a genuine question if you do know the answer because I would actually really like to know.
For atoms as big as stratum, they hey are kinda of like spheres. Atoms are surrounded by an electron wave cloud. The electron wave is a standing wave that sloshes near the atom.
The wave cloud represents the probability that an electron will be found at a location when its time to measure.
Picturing that is... Yeah, I'm not smart enough for that I don't think.
I'm sort of picturing like, an asteroid field around a planet but instead it's an atom and electrons. Am I even vaguely close? ;
It is pretty complex and mind bending to understand. I don't even understand all of it. Here is site that shows what the hydrogen atom electron waves looks like in 3d.
https://www.falstad.com/qmatom/
Every particle we see has a associated field. So the electron has a electron field. The amplitude of the electron field at any point is associated with the probability a electron will be observed there. This wave-function to probability is a weird fact of quantum physics. It means the wave can slosh over barriers or interact with itself and the electron will tunnel or interact with itself(even when there is one electron).
We only see the electron when measuring it, when not measuring the electron field evolves according to quantum equations. The electron wave in a atom hovers and sloshes around a atom.
So what smaller than that atom then?
I think it's absolutely incredible that we've done this.
Impressive, but under the right conditions a human eye can detect a single photon, so not shocking that this is possible.
I wish strontium was a better name for a metal band because I’d name my band strontium all day long.
puts on davie504 Italian voice pinches fingers: STRONTIUM!
Poor atom they are abusing they shit out of it.
Fun fact, "stront" is a word for shit in Dutch. Still, an amazing picture, but also a tiny bit funny because of strontium.
Akira!
What exists in the space between the atom and the electrodes?
I thought this was a photocopying machine with the lid up
What element?
the most meaningful photo in my entire life I've ever seen
How they get da atom in thar
An atom visible without a microscope.. sure
You're actually seeing the electron cloud around the strontium nucleus glowing, which is much much larger than the actual nucleus. It is also a zoomed-in long exposure photo. IRL you probably could not see it due to the low intensity of emitted light.
Yes if this atom was next to other atoms as closely packed as in a solid, you wouldn’t be able to resolve it from the other atoms around. But there is only one ion trapped in this radiofrequency trap. This atom is the only thing that strongly scatters light from a laser pointed through the trap, so it acts as a single point source of light. It’s exactly the same as how you can see a star although the star is too small for you to resolve the size of the star with your eyes.
Nadlinger? I wonder how many times they called him nad licker growing up