The universe is Constantly show us its history. For example: information about what happened, long Previously, contained in long radio waves ubiquitous throughout the universe may contain detailed information about how the first stars and black holes formed. But there is a problem. Due to the noisy radio signals generated by our atmosphere and modern society, we cannot read them from the earth.

This is why NASA is in the early stages of planning to build an automated research telescope on the far side of the moon.One of the most ambitious proposals is to establish Lunar Crater Radio Telescope, The largest (many) full-aperture radio telescope antenna in the universe.Another project portfolio, called remote with Vision, Will connect a large number of antennas-eventually more than 100,000, many of which are built on the moon itself and made of its surface materials-to receive signals. These projects are part of NASA’s Institute for Advanced Concepts (NIAC) program, which provides funding to innovators and entrepreneurs to advance radical ideas and create breakthrough aerospace concepts. Although they are still hypothetical and several years away from reality, the discoveries of these projects may reshape our universe model.

“With the help of a telescope on the moon, we can reverse engineer the recorded radio spectrum and infer the properties of the first stars for the first time,” said cosmologist Jack Burns of the University of Colorado at Boulder. -Investigator and scientific leader of FarSide and FarView. “We care about the first stars because we care about our own origins-I mean, where do we come from? Where do we come from? Where does the earth come from? The Milky Way?”

The answers to these questions came from a dim moment in the universe about 13.7 billion years ago.

When the universe cooled about 400,000 years after the Big Bang, the first atom, neutral hydrogen, released photons in an electromagnetic radiation burst that scientists can still see today. This cosmic microwave background (CMB) was first detected in 1964. Today, scientists use sophisticated tools such as the European Space Agency’s Planck probe to detect its tiny fluctuations, thereby creating a snapshot view of the distribution of matter and energy in the young universe. Thanks to the visual data collected from starlight by telescopes like Hubble, scientists can also fast-forward about 100 million years to study most of the roughly 13 billion years since the formation of the first stars or “cosmic dawn” ( Soon, the upgraded James Webb). They allow us to see so far that we are actually looking back at the past.

After the initial fireball of the Big Bang subsided to the CMB, but before the first stars began to burn, there was little light in the universe for a while. Scientists call this period of no visible or infrared light the “dark age of the universe.” In this era, the universe seems very simple, mainly composed of neutral hydrogen, photons and dark matter. Evidence of what happened during this period may help us understand how dark matter and dark energy are formed-according to our best guess, they account for about 95% of the mass of the universe, but to a large extent they are What is invisible, we still don’t really understand it-shaping its formation.

The clues about what happened in the dark ages of the universe are hidden in hydrogen, which still constitutes most of the known matter in the universe. Every time the electron spin of a hydrogen atom flips, it emits a radio wave of a specific wavelength: 21 centimeters. But those wavelengths released in the dark age of the universe were not actually 21 centimeters long when they reached the earth. As the universe is expanding rapidly, the wavelength of hydrogen will also expand, or “redshift”, extending when they travel a great distance. This means that the length of each wave is like a timestamp: the longer the wave, the older it is. When they reach the earth, their length is more like 10 meters or even 100 meters, and the frequency is lower than the FM band.

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