This article was originally published on The Conversation. The book donated the article to Space.com Soundtracks: Op-Ed & Insights.
Carolyn DevereuxProfessor of Astrophysics, University of Hertfordshire
The Hubble Space Telescope spotted the farthest star ever seen – Earendel, the morning star. Even though Earendel is 50 times the magnitude of the sun, and a million times brighter, we can’t see it. We can see it because the star sits with a large galaxy cluster in front of it whose gravity diverts the light from the star to make it brighter and more realistic – actually creating a lens.
Astronomers know very ancient times when we look at long distances. Light travels at a constant speed (3×10 ^ 8 meters per second) so the farther away an object is, the longer it takes the light to reach us. When light comes to us from the most distant stars, the light we observe can be billions of years old. So we look at past events.
When we look at the light of a star, we are looking at the light emitted from a star 12.9 billion years ago – we call this the retrospective period. That was only 900 million years after the Big Bang. But because the universe was expanding rapidly when this light was taken to us, Earendel is now 28 billion years lighter than us.
Now Hubble’s last, the James Webb Space Telescope (JWST), has been able to see stars before, although not many are well -designed to create a “gravitational lens” that we can use. See. .
Pili: Join Earendel: The Hubble telescope astronomy has a name coined by Tolkien.
To see the past again, things need to be very shiny. And the farthest things we can see are the largest and brighter galaxies. Very bright galaxies with quasars – bright objects thought to be stimulated by supermassive black holes – are in them.
Prior to 1998, the largest quasar galaxies ever observed were about 12.6 billion years old. The Hubble Space Telescope’s observation time has increased the observation time to 13.4 billion years, and JWST expects to improve this to 13.55 billion years for galaxies and stars.
The formation of stars began hundreds of millions of years after the Big Bang, at what we call the cosmic dawn. We want to see the stars at the cosmic dawn, because it can confirm our impressions of the functioning of the universe and galaxies. That said, research shows that we can’t see long distances with telescopes in as much detail as we would like – there may be a universal resolution limit.
Why look back?
One of the main goals of JWST is to understand the nature of the universe and when the first stars and galaxies were formed, which are estimated to be between 100 million and 250 million galaxies. years after the Big Bang. And luckily, we can get advice on this by looking back before Hubble or JWST can navigate.
We can see light from 13.8 billion years ago, even though it was not a starlight – there were no stars then. The farthest light we can see is the cosmic microwave background (CMB), which is the light left over from the Big Bang, built 380,000 years after we were born.
The entire universe before the formation of the CMB was composed of fixed fractions of positive protons (i.e. what is now the atomic nucleus with neutrons) and negative electrons, and with ease. The light was scattered by the charged pieces, which turned the whole world into a misty soup. As the universe expands, it cools until the electrons combine with the protons to form atoms.
Unlike the soup of particles, the atoms have no role, so the light is no longer scattered and can move around the universe in a straight line. This light continues to travel throughout the world to this day. The long wave of light has been expanding the universe – and we now know them as microwaves. This light is the CMB and can be seen in all parts of the sky. The CMB is located in all parts of the world.
The CMB light is the longest last we have ever seen, and we cannot see the light from the past because that light is scattered and the earth is opaque.
There are times, but we can see a day outside the CMB. To do this, we can’t use light – we have to use gravitational waves. These are waves in the fabric of spacetime itself. If someone was created in the mist of the entire universe, then they can come to us today.
In 2015, gravity waves were detected from the combination of two black holes using the LIGO sensor. Perhaps the entire universe could be seen before the CMB was founded 13.8 billion years ago.
This article is republished under The Conversation under a Creative Commons license. Read the original article.
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