Nobel Prize in Astronomy? Nonsense, you will say, there is no such thing! And you will be right! Today I would like to talk about the Nobel Prizes in Physics awarded for the discoveries directly related to Astronomy. Of course, many scientific advances contributed to the modern understanding of Space. But let’s look at those few that achieved the highest scientific recognition.
Victor Franz Hess received the Nobel Prize “for the discovery of cosmic radiation”.
Hess, an Austrian-American scientist, studied the phenomenon of the charged Earth’s atmosphere. The ionization of the atmosphere was well known before Hess, but physicists didn’t know what caused it. The original idea, that the radiation comes from the ground, was contradicted by Hess’s famous balloon experiments. The scientist himself flew the balloon to the altitude of over 5000 kilometers and showed that the ionization of the atmosphere increases with the distance from the ground. Therefore the radiation comes from Space, not Earth! Now we know that the Supernova explosions are the main source of the cosmic radiation. Although our Sun also contributes to the stream of the high-energy particles.
Hans Bethe received the Nobel Prize “for the contribution to the theory of nuclear reactions, especially his discoveries concerning the energy production in stars”
Bethe was a German -American nuclear physicist. Many people know him as one of the Manhattan project scientist. Bethe was the first to come up with the explanation how the Sun-like stars (proton-proton reaction) and stars, heavier than the Sun (CNO cycle) produce their energy.
Martin Ryle and Antony Hewish received the Nobel Prize “for the pioneering research in radio astrophysics”.
Ask any astronomer what comes to their mind when they hear the name of Martin Ryle and they will say two things: interferometry and aperture synthesis. (Is it even English?)
The problem with astronomical telescopes is that the resolution of a single telescope is limited by the size of the telescope itself. But what is we use a cluster of telescopes working together as one giant telescope? In theory, such instrument’s “mirror” (or dish if it’s a radio telescope) will be as big as the distance between the separate telescopes. Therefore we will achieve a much higher resolution! This is called astronomical interferometry. Ryle and his colleagues constructed the first two- component radio interferometer (two radio telescopes on rails placed about a mile apart). They used the new instrument to observe the farthest radio sources to date. Ryle also developed the method , known as aperture synthesis. In the simplest two- telescopes version of this method, the telescopes scan the source as the Earth spins around (that gives the telescopes a different angle of view). Then the high-resolution image of the object is restored from the combined signals using a special mathematical technique.
Another English Astronomer received the Nobel Prize for the discovery of the first pulsar. Pulsars are fast rotating compact objects, usually neutron stars, that emit two beams of radiation in the opposite directions. The axis of the radiation beam is not in line with the axis of rotation. This produces the strange observational effect of “pulsing”. Imagine spinning the flashlight on the horizontal surface in front of you. The light beam will only be shining in your direction for a short period but at regular intervals. Now if you are far enough from the flashlight, you will not be able to see the source, only the light. Coming in pulses!
Back in 1967 Hewish and his team designed and built a radio telescope to look for a very interesting space objects called quasars. One of his graduate students, Jocelyn Bell, was in charge of operating the telescope and proceeding the data. She was the first to notice the strange signal, that kept appearing at regular intervals once every 1.3 seconds. First, the team ruled out all the possible terrestrial sources, then they thought it could be a signal from an alien civilization! Later Bell spotted a similar signal from a different area of the sky. That meant the sources were some new objects, not aliens. A few years later scientists finally explained the nature of pulsars. Hewish received an award in recognition of his initial discovery. Many scientists agree, that Bell should have shared the award too!
Arno Penzias and Robert Woodrow Wilson received a Prize “for the discovery of cosmic microwave background radiation (CMB)”
This is one of my favourite examples of how what looked like an observational mistake became one of the greatest discoveries in the history of Astronomy.
It all started with the Holmdel Horn Antenna owned by Bell Labs. This radio telescope was built to support NASA’s satellite project Echo. When it was no longer needed, the two Bell Lab scientists, Penzias and Wilson, jumped at the opportunity to use the antenna for the astronomical observations. They were planning to use it to study the interstellar gas in the Milky Way Galaxy.
But as they started to test the equipment, they noticed the funny background noise on the wavelength of 7.35 cm. The noise was coming from all directions and had an effective temperature of about 3K.
Penzias and Wilson worked really hard to get rid of the noise. First they made sure the source of the signal was not man-made. Then they checked all the sources in the Solar System and even in the Galaxy they could think of. Nothing could explain the it! They had two option: either the signal came from outside the Galaxy or it was a mistake, something to do with the telescope itself. The pigeons lived in the horn and the antenna was covered in the pigeon’s droppings. Could they be responsible for that 3K signal? Penzias and Wilson cleared the antenna and covered it with a net. The signal still remained. Around the same time a group of astronomers from Princeton University was about to publish the theoretical paper about the Big Bang and its leftover radiation. They expected to find it in microwaves (radio waves about a few cm long).
The two groups of astronomers met to discuss their theories and findings. Soon they published two papers. One was about the theoretical prediction of the CMB, and another, by Wilson and Penzias, about the discovery of the 3K background radiation. Wilson and Penzias offered CMB as a possible explanation to their discovery.
Why was it so important? Back then, there were two rival theories about the origin of the Universe: Big Bang Theory and Steady-State Theory. The discovery of the CMB was the prove that everything started with the Big Bang!
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