What do photons look like

We have to "collapse" it in order to observe it, and then we only know where it collapsed to. Different measuring devices record that in different ways, typically as the sudden energetic excitation of an electron bound to some atom.

The wave is so impenetrable that we tend to regard it as a wave of possibilities, telling us only the probability of where we might find it when we observe or collapse it. We often find the word "particle" convenient when talking about it, but be under no illusion; this is nothing like a "classical" particle, it is just a word we have inherited from the past to describe something extremely weird and which we do not yet understand. Quantum physicists adjure each other to "shut up and calculate" for very good reason.

Nice question. For object to be seen directly ,- it needs to scatter photons. That much energy can be only produced in CERN or similar particle accelerator laboratories. First photon-photon scattering was observed in You can look at more complete overview of photon-photon scattering research. As much as I can say, this is very intensive research area, and not closed yet, so many work needs to be done.

Photons are undoubtedly one of the most fascinating quantum phenomena in physics. You hear phrases like "quantum of light". Just to define them is an art. What exactly is a quantum of light? How do electromagnetic waves carry quantised energy? You see from the image that even when we talk about the particle or wave nature of light, we can easily get confused.

Now you are asking whether photons have ever been physically observed, and the answer is yes, we do have something called the single photon detector. Please note that even our eyes can and do sometimes detect even single photons, even though our brain might need more then one photon to consciously perceive it as light.

We do see things in a series of flashes. One photon excites one rhodopsin molecule in our retina and our optic nerve sends a signal every time this happens. However under normal circumstances the number of photons per second detected by the eye is so large that the signals received by the brain are effectively continuous so we don't see any oscillation in our vision. If light carries its energy in discrete packets, why don't we see a series of flashes when we look at things?

Now you are asking what a photon looks like. There are two ways to answer this. On the one hand, when we talk about what an object looks like, we think about how photons bounce off of it and then create an image in our brain. But this way we cannot talk about what a photon looks like, because to do that we would have to bounce photons off of a photon but photons do not interact like that, only at high energy levels , and see what image that creates.

On the other hand, photons themselves are the things that we perceive and our brain interprets them in reality a combination of as having color.

The photon the high energy experimenter talks about is a small particle that is not possible to see in photos of the particle tracks and their scattering events.

What exactly is a photon? So the answer to your question is that photons are fascinating phenomena and represent a form of energy quanta of the EM field , and they look like whatever form that piece of energy takes.

To us, our brain makes it possible to interpret them as color, which corresponds to their wavelength, but ultimately this is just our perception of this form of energy. Everything we see looks like photons Our eyes are impressively good not only at detecting photons, but at sorting the photons by energy and direction as well. This is how we get colors and shapes. Outside of this, "photon" is just a model for a pretty wide range of interactions. Does it have a shape? Are these questions even meaningful?

Now, Polish physicists have created the first ever hologram of a single light particle. The feat, achieved by observing the interference of two intersecting light beams, is an important insight into the fundamental quantum nature of light.

The result could also be important for technologies that require an understanding of the shape of single photons — such as quantum communication and quantum computers. For hundreds of years, physicists have been working to figure out what light is made of. But things got a bit more complicated at the turn of the 20 th century when German physicist Max Planck, then fellow countryman Albert Einstein, showed light was made up of tiny indivisible packets called photons.

The concept of the photon was born. But Planck didn't comprehend the profundity of his idea. He later described his breakthrough as "an act of desperation"—an unsubstantiated trick to make the math work out. Albert Einstein, too, resisted implications of the photon theory that he helped to develop. He was particularly bothered by entanglement, the idea that two particles can have intertwined fates, even when they are separated far apart from each other.

The theory implied, for example, that if you measured the polarization of one photon in an entangled pair, you would instantly also know the polarization of the other, even if the two particles have been separated to opposite ends of the solar system.

Entanglement suggested that objects can influence each other from arbitrarily far away, known as nonlocality, which Einstein derided as "spooky action at a distance. For decades, arguments over the photon were largely relegated to the realm of thought experiments, as it was technologically impossible to test these ideas.

Recently, the debate has trickled into the physics community more broadly, as single-photon sources and detectors become better and more widely accessible, according to Steinberg. For example, physicists have all but confirmed the existence of entanglement. Decades of experiments, known as tests of Bell's inequality, now strongly indicate that Einstein was wrong—and that our universe is nonlocal.

These tests are based on an experimental framework devised by the UK physicist John Stewart Bell in In theoretical work, Bell showed that if you repeat measurements on purportedly entangled particles, the statistics could reveal whether the photons truly influence each other nonlocally, or if an unknown mechanism—known generically as a "local hidden variable"—creates the illusion of action at a distance.

In practice, the tests have largely involved splitting up pairs of entangled photons along two different paths to measure their polarizations at two different detectors. Physicists have been performing Bell tests since the s, with all published experiments indicating photons can spookily act from a distance, as physicist David Kaiser of the Massachusetts Institute of Technology explains. However, despite unanimous results, these early experiments were inconclusive: Technology shortfalls meant their experiments suffered from three potential design limitations, or loopholes.

The first loophole, known as the locality loophole, arises from the two polarization detectors being too close together. Theoretically, it was possible that one detector could have relayed a signal to the other detector right before the entangled photons are emitted, influencing the outcome of the measurement locally.

The second loophole, called the fair sampling loophole, resulted from poor-quality single-photon detectors. Experts argued that the detectors could have caught a biased subset of the photons, skewing the statistics. The desire to close this loophole, says Migdall, has driven the development of better single-photon detectors, the same now used routinely in quantum technologies.

The third loophole, the freedom-of-choice loophole, is related to the settings of the polarization detector. To get truly unbiased statistics on a large number of polarization measurements, the orientation of the polarization detector must be randomly reset for each measurement.

It is difficult to guarantee randomness, with researchers painstakingly resetting the detectors by hand in early experiments. Recent experiments have closed all three loopholes, albeit not simultaneously in one test, according to Kaiser.

In , a team led by physicist Ronald Hanson at the Delft University of Technology performed a Bell test that closed the fair sampling and locality loopholes for the first time, albeit using entangled electrons rather than photons. Radio waves and microwaves; infrared and ultraviolet light; X-rays and gamma rays: All of these are light, and all of them are made up of photons.

Photons are at work all around you. They travel through connected fibers to deliver internet, cable and cell phone signals. They are used in plastics upcycling, to break down objects into small building blocks that can be used in new materials.

They are used in hospitals, in beams that target and destroy cancerous tissues. Photons are essential in cosmology: the study of the past, present and future of the universe. Scientists study stars by examining the electromagnetic radiation they emit, such as radio waves and visible light.

Astronomers develop maps of our galaxy and its neighbors by imaging the microwave sky. They detect space dust that blocks their view of distant stars by detecting its infrared light.

Scientists collect strong signals, in the form of ultraviolet radiation, X-rays, and gamma rays emitted by energetic objects from our galaxy and beyond. And they detect weak signals, such as the faint pattern of light known as the cosmic microwave background, which serves as a record of the state of the universe seconds after the Big Bang.

In , scientists at the Large Hadron Collider discovered the Higgs boson by studying its decay into pairs of photons. Physicist Donna Strickland won a share of the Nobel Prize in Physics in for her work developing ultrashort, high-intensity laser pulses, formed from highly focused high-energy light. Machines called light sources create intense beams of X-rays, ultraviolet light and infrared light to help scientists break down the steps of the fastest chemical processes and examine materials in molecular detail.

Dionne conducts research in the field of nanophotonics, a subfield of physics in which scientists control light and study its interactions with molecules and nano-sized structures. Among other projects, her lab uses photons to up the effectiveness of catalysts, substances used to kick off high-efficiency chemical reactions. Light can bring a whole new dimension and an entirely new tool kit.