How Scientists Are Hunting for the Universe’s First Stars
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How Scientists Are Hunting for the Universe’s First Stars

November 30, 2019

Looking through a telescope is like looking back in time. Because light has a finite speed limit, the farther away you look, the deeper into the past you see. With radio telescopes we can even see the universe as it was just after the big bang, nearly 13.8 billion years ago. But after that early snapshot, there’s about a billion years we haven’t been able to see clearly. Cosmologists call this the dark ages, and probing into this hidden era of the universe can tell us more about how it took shape, and even the nature of dark matter. First, let’s take it back. Way, way back to almost the very beginning, about 380,000 years after the big bang kicked off this whole thing we call existence. That’s the point when the free protons and electrons were cool enough to start combining into the simplest and most abundant of atoms, hydrogen. That’s when the universe goes dark. Most hydrogen doesn’t emit light in the vast majority of the electromagnetic spectrum. That’s not to say it’s totally invisible, it does give off and absorb electromagnetic radiation when it’s electron switches between two states, but at the relatively long wavelength of slightly over 21 centimeters. This means that if hydrogen gives off or absorbs radiation, it should be detectable, what’s known as the hydrogen line. But plucking out the signal of ancient hydrogen from the rest of the radiation that we constantly get bombarded with, is tricky. Since it’s traveled for such a long time to reach us, the space it’s moved through has itself stretched out quite a bit, which in turn elongates the wavelength from about 21 centimeters, to one and a half to 20 meters. The longer the wavelength, the older the signal. And the deeper the redshift, the weaker the signal becomes, until its easily masked by noise from the Milky Way, or human activity like radio broadcasts, or even spark plugs in cars. Thankfully, the tools cosmologists use to see the history of the universe are getting better all the time. They’re setting up radio telescopes and antennae around the world, sometimes in remote locations to avoid human interference, like an island between South Africa and Antarctica, or on a lake in the Tibetan Plateau. New technology is making the enormous amounts of data these observatories churn out easier to analyze. Now scientists think they can finally start sussing out what happened in the dark ages. There are three periods when hydrogen absorbed or emitted energy that should be discernable. The first occurred 5 million years after the big bang, when hydrogen cooled enough to absorb some of the background radiation, causing a dip in the hydrogen line known as the dark-ages trough. About 200 million years later, the first stars and galaxies formed, giving off ultraviolet radiation that made the hydrogen more readily absorb 21-cm photons. This should appear as a second, more pronounced dip at a shorter wavelength. Finally, the third major event that affected hydrogen is called the Era of Reionization, or EOR. Around the universe’s 500 millionth birthday, the UV radiation from stars and galaxies would have grown so bright that it would cause hydrogen to fluoresce, emitting 21 cm waves. But the hydrogen that was too close to the galaxies was bombarded with so much radiation, that it was stripped of their electrons altogether. Separated again, the now free protons and electrons would go dark, so a snapshot of this time period would have ionized bubbles of darkness with brighter radiation in between. The EOR is the time period most experiments are investigating. One group of researchers in Australia recently announced that by using a new technique to process data from a collection of over 4000 antennae called the Murchison Widefield Array, they were able to generate a 10-fold improvement in their results, helping them hone in on when the EOR began. And just last year, an antenna in the Australian outback called EDGES may have seen the first glimpses of the ionized hydrogen bubbles around the first stars. The goal is to make a 3D map of these bubbles, and by examining different wavelengths we’ll be able to see exactly how the universe grew and evolved. Neat uniform bubbles will tell us that early stars were responsible for the reionization, while wispy, freeform bubbles would suggest the presence of black holes. Signals from the EOR could even give us a clue about how to look for dark matter, indicating whether it’s made up of sluggish and cold particles, or warm ones that are lighter and faster. Before any of this can happen though, we need to start finding that 21 cm wavelength in the data we’re collecting. Once more arrays are online and more data is parsed, we might be able to shed some light on the universe’s dark ages and the very first days of our galaxy. Another instrument that will search for the universe’s first days is the James Webb Telescope, slated to launch in the early 2020s. Here’s a How Close Are We episode on the long awaited telescope. Is there another astronomical phenomenon that you’d like us to cover? Let us know down in the comments. Make sure to subscribe to Seeker and thanks for watching.

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  1. Cool theory, bit outdated info tho in 2019… considering humans dont even know what light is, but hey, scientists used to think the sun was powered by Coal and that flying machines were against physics not too long ago :D.
    Mmm why dont you do a video on Halton Arp's intrinsic red shift…. or how Kristian Birkeland about his Birkeland Currents which connect our Sun to most the bodies in the solarsystem – and most probably our Sun to the center of the galaxy.
    But I guess they dont pay you to do actual science and make people think, just drill this dark matter big bang nonsense into their minds 😉

  2. After 13 billion years I wonder what those stars look like now and which are gone. I wonder if they have some kind of civilizations around them. There’s no way for us to know until the light gets here.

  3. Wormholes maybe more common then blacks holes but much shorter life spans. And most subatomic. But if you had computer that predicted when wormholes& where to generate them . And when they would fuse . And send charge's to farther them open.
    .if negative Mass doesn't exist how can we push on anything if you only create an eara zero space around your ship. You can at move out side of time . instead of just jump from your prospective

  4. What if our big bang is one of an infinite amount meaning there are other universes and more being created all the time but just to far apart for us to see

  5. Thank you for this! we made “Channel Water” and are dedicated to these issues. Please subscribe and share if you can. Hope to collaborate in the future!

  6. What if the stars that they have assigned a color to depicting whether they are traveling towards or away from us are those colors because they are those colors and movement towards or away does not mean shit?

  7. Why do we call "exoplanets", planets, when we don't have the technology to determine if these objects orbiting exostars have cleared their orbits? After all, that IS the third and crucial definition of a planet according to the IAU, and the reason why Pluto got demoted. Shouldn't we instead call these orbiting objects "Exo Sub Stellar Objects", ESSOs, and not exoplanets?

  8. The speed of light as nothing to do with the instant action at a distance that occurs with quantum entangled fields upon observation. Thus we are NOT able to look into the past which has never been proven! In fact every galaxy that was observed to be beyond 13 billion light years away was extremely large and too bright to be called young galaxies, basically disproving the notion that we are able to see into the past because of the speed of light.

  9. Space doesn't stretch. It slowly increases in volume near mass because mass adds energy to space. Note, if matter and energy are equal and matter takes up volume in space then energy would also take up volume in space because it is equal to matter. Thus when a star radiates energy and particles into space those actions cause the volume of space to slowly increase around the star. Now add up the amount of stars in space with distance and you can see how this would cause space to expand exponentially with the distance being observed. Dark energy or the action of space increasing in volume is thereby caused by stars, mass. Matter is not only responsible for gravity but it is also responsible for the action pinned on dark energy. You're welcome.

  10. #Seeker Were does all the energy go and if so how far is it from us until The Heat death of the Universe affects us like a start of an ice age?

  11. I hope they find them. Then the work they're doing at the telescope office will have paid off. Those amazing scientists deserve every penny. Their degrees make them worthy people of all they have. This stuff is important for mankind. We gotta know where those stars are.

  12. By assuming that an unproven theory is fact and plunging ahead. The Big Bang is a Theory, since when did science forget that they must prove foundation theories before moving on?

  13. I know three of the names on your shirt, but I don't know Jemison or Wu. Though the latter of those two is an incredibly common last name.

  14. Why don’t they show us these images from the telescopes and satellites?
    Why are we always given CGI images or An artists concept of what’s out there? With all these telescopes and satellites ??‍♂️ smh

  15. The idea of the Big Bang is a simply a theory that cannot ever be proven. Furthermore, order does not come from chaos!

  16. Your big Bang theory is in erroneous observation we are from singularities emitted from galactic cores, that is the illusion of the big bang concept!

    We are created from singularities emission from the galactic cores

  17. so technically speaking, if we finally find definitive proof on how the universe started by looking that far all religions will blow up

  18. 21 cm is the result of spin flipping of electrons in very cold hydrogen clouds. During reionization hydrogen atoms were absorbing UV and visible photos that were exciting electrons or ionizing them altogether. These two things are not the same.

  19. Looking into a telescope is like looking back in time. That's because telescopes are time machines, which is how we know anything about history and people like George Washington.

  20. Sooner or later we will reach the moon. Far side is the perfect location for this kind of astronomy. No spark plugs there.

  21. Have you seen the GEICO commercials with the little lizard? Gecko-GEICO, get it? Ask yourself, why has this marketing icon been around since about 1999. GEICO spends over a BILLION USD in total advertising. Ask yourself, "Why?" What does this mean to and for America? Why the "popularity" of the gecko? Why since 1999? I'll tell you" it's a scream for release. A mental fart.

  22. I watch this little kid and wonder who the fk he is. His words just blabber and make no sense to me. I quit at 1:05 and unsubscribed.

  23. "…Julian originally planned a career as a Hockey play-by-play commentator but his skills of delivering information quickly and tinged with humor have made him an ideal educator for the YouTube age. He is best known for The Science of Happiness and The Science of Love on SoulPancake. He's also a regular guest host on DNews…."

  24. It only stands to reason that the oldeat star is simply the biggest super massive black hole… you welcome.

  25. There will come a time when all the light from the start of the universe has traveled "past" us, and there is no more light from that time to see. I wonder when that will be.

  26. What if we placed a mirror on the opposite side of the universe as Earth, would we be able to see the past of the Earth

  27. To look in the back way and vice versa of everything moving is enough to move faster of those. It is absolutely not the speed of light which carries out this obligation. We see the light moving with speed because we ascertain the light performed in the same moment absolutely with zero speed and vice versa.

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