The Times Australia
The Times World News

.

The most powerful space telescope ever built will look back in time to the Dark Ages of the universe

  • Written by Chris Impey, University Distinguished Professor of Astronomy, University of Arizona
The most powerful space telescope ever built will look back in time to the Dark Ages of the universe

Some have called NASA’s James Webb Space Telescope the “telescope that ate astronomy[1].” It is the most powerful space telescope[2] ever built and a complex piece of mechanical origami that has pushed the limits of human engineering. On Dec. 18, 2021, after years of delays and billions of dollars in cost overruns, the telescope is scheduled to launch into orbit[3] and usher in the next era of astronomy.

I’m an astronomer[4] with a specialty in observational cosmology – I’ve been studying distant galaxies for 30 years. Some of the biggest unanswered questions about the universe relate to its early years just after the Big Bang. When did the first stars and galaxies form? Which came first, and why? I am incredibly excited that astronomers may soon uncover the story of how galaxies started because James Webb was built specifically to answer these very questions.

A graphic showing the progression of the Universe through time.
The Universe went through a period of time known as the Dark Ages before stars or galaxies emitted any light. Space Telescope Institute[5]

The ‘Dark Ages’ of the universe

Excellent evidence shows that the universe started with an event called the Big Bang[6] 13.8 billion years ago, which left it in an ultra-hot, ultra-dense state. The universe immediately began expanding after the Big Bang, cooling as it did so. One second after the Big Bang, the universe was a hundred trillion miles across with an average temperature of an incredible 18 billion F (10 billion C). Around 400,000 years after the Big Bang, the universe was 10 million light years across and the temperature had cooled[7] to 5,500 F (3,000 C). If anyone had been there to see it at this point, the universe would have been glowing dull red like a giant heat lamp.

Throughout this time, space was filled with a smooth soup of high energy particles, radiation, hydrogen and helium. There was no structure. As the expanding universe became bigger and colder, the soup thinned out and everything faded to black. This was the start of what astronomers call the Dark Ages[8] of the universe.

The soup of the Dark Ages was not perfectly uniform[9] and due to gravity, tiny areas of gas began to clump together and become more dense. The smooth universe became lumpy and these small clumps of denser gas were seeds for the eventual formation of stars, galaxies and everything else in the universe.

Although there was nothing to see, the Dark Ages were an important phase in the evolution of the universe.

A diagram showing different wavelengths of light compared to size of normal objects. Light from the early universe is in the infrared wavelength – meaning longer than red light – when it reaches Earth. Inductiveload/NASA via Wikimedia Commons, CC BY-SA[10][11]

Looking for the first light

The Dark Ages ended when gravity formed the first stars and galaxies that eventually began to emit the first light. Although astronomers don’t know when first light happened, the best guess is that it was several hundred million years[12] after the Big Bang. Astronomers also don’t know whether stars or galaxies formed first.

Current theories[13] based on how gravity forms structure in a universe dominated by dark matter suggest that small objects – like stars and star clusters – likely formed first and then later grew into dwarf galaxies and then larger galaxies like the Milky Way. These first stars in the universe were extreme objects compared to stars of today. They were a million times brighter[14] but they lived very short lives. They burned hot and bright and when they died, they left behind black holes[15] up to a hundred times the Sun’s mass, which might have acted as the seeds for galaxy formation[16].

Astronomers would love to study this fascinating and important era of the universe, but detecting first light is incredibly challenging. Compared to massive, bright galaxies of today, the first objects were very small and due to the constant expansion of the universe, they’re now tens of billions of light years away from Earth. Also, the earliest stars were surrounded by gas left over from their formation and this gas acted like fog that absorbed most of the light. It took several hundred million years for radiation to blast away the fog[17]. This early light is very faint by the time it gets to Earth.

But this is not the only challenge.

As the universe expands, it continuously stretches the wavelength of light traveling through it. This is called redshift[18] because it shifts light of shorter wavelengths – like blue or white light – to longer wavelengths like red or infrared light. Though not a perfect analogy, it is similar to how when a car drives past you, the pitch of any sounds it is making drops noticeably.

Similar to how a pitch of a sound drops if the source is moving away from you, the wavelength of light stretches due to the expansion of the universe.

By the time light emitted by an early star or galaxy 13 billion years ago reaches any telescope on Earth, it has been stretched by a factor of 10 by the expansion of the universe. It arrives as infrared light, meaning it has a wavelength longer than that of red light. To see first light, you have to be looking for infrared light.

[The Conversation’s science, health and technology editors pick their favorite stories. Weekly on Wednesdays[19].]

Telescope as a time machine

Enter the James Webb Space Telescope.

Telescopes are like time machines. If an object is 10,000 light-years away, that means the light takes 10,000 years to reach Earth. So the further out in space astronomers look, the further back in time we are looking[20].

A large golden colored disc with a sensor in the middle and scientists standing below. The James Webb Space Telescope was specifically designed to detect the oldest galaxies in the universe. NASA/JPL-Caltech, CC BY-SA[21][22]

Engineers optimized James Webb[23] for specifically detecting the faint infrared light of the earliest stars or galaxies. Compared to the Hubble Space Telescope, James Webb has a 15 times wider field of view on its camera[24], collects six times more light and its sensors are tuned to be most sensitive to infrared light.

The strategy will be to stare deeply at one patch of sky for a long time[25], collecting as much light and information from the most distant and oldest galaxies as possible. With this data, it may be possible to answer when and how the Dark Ages ended, but there are many other important discoveries to be made. For example, unraveling this story may also help explain the nature of dark matter[26], the mysterious form of matter that makes up about 80% of the mass of the universe[27].

James Webb is the most technically difficult mission[28] NASA has ever attempted. But I think the scientific questions it may help answer will be worth every ounce of effort. I and other astronomers are waiting excitedly for the data to start coming back sometime in 2022.

References

  1. ^ telescope that ate astronomy (doi.org)
  2. ^ most powerful space telescope (www.jwst.nasa.gov)
  3. ^ scheduled to launch into orbit (theconversation.com)
  4. ^ astronomer (scholar.google.com)
  5. ^ Space Telescope Institute (webbtelescope.org)
  6. ^ Big Bang (www.space.com)
  7. ^ temperature had cooled (www.astro.ucla.edu)
  8. ^ Dark Ages (astronomy.com)
  9. ^ not perfectly uniform (wmap.gsfc.nasa.gov)
  10. ^ Inductiveload/NASA via Wikimedia Commons (commons.wikimedia.org)
  11. ^ CC BY-SA (creativecommons.org)
  12. ^ several hundred million years (earthsky.org)
  13. ^ Current theories (astronomy.com)
  14. ^ a million times brighter (webbtelescope.org)
  15. ^ black holes (astronomy.com)
  16. ^ acted as the seeds for galaxy formation (astronomynow.com)
  17. ^ radiation to blast away the fog (www.quantamagazine.org)
  18. ^ redshift (www.esa.int)
  19. ^ Weekly on Wednesdays (theconversation.com)
  20. ^ further back in time we are looking (astronomy.swin.edu.au)
  21. ^ NASA/JPL-Caltech (www.nasa.gov)
  22. ^ CC BY-SA (creativecommons.org)
  23. ^ optimized James Webb (www.jwst.nasa.gov)
  24. ^ James Webb has a 15 times wider field of view on its camera (www.jwst.nasa.gov)
  25. ^ stare deeply at one patch of sky for a long time (www.nasa.gov)
  26. ^ help explain the nature of dark matter (doi.org)
  27. ^ 80% of the mass of the universe (www.space.com)
  28. ^ most technically difficult mission (futurism.com)

Read more https://theconversation.com/the-most-powerful-space-telescope-ever-built-will-look-back-in-time-to-the-dark-ages-of-the-universe-169603

Times Magazine

Headless CMS in Digital Twins and 3D Product Experiences

Image by freepik As the metaverse becomes more advanced and accessible, it's clear that multiple sectors will use digital twins and 3D product experiences to visualize, connect, and streamline efforts better. A digital twin is a virtual replica of ...

The Decline of Hyper-Casual: How Mid-Core Mobile Games Took Over in 2025

In recent years, the mobile gaming landscape has undergone a significant transformation, with mid-core mobile games emerging as the dominant force in app stores by 2025. This shift is underpinned by changing user habits and evolving monetization tr...

Understanding ITIL 4 and PRINCE2 Project Management Synergy

Key Highlights ITIL 4 focuses on IT service management, emphasising continual improvement and value creation through modern digital transformation approaches. PRINCE2 project management supports systematic planning and execution of projects wit...

What AI Adoption Means for the Future of Workplace Risk Management

Image by freepik As industrial operations become more complex and fast-paced, the risks faced by workers and employers alike continue to grow. Traditional safety models—reliant on manual oversight, reactive investigations, and standardised checklist...

From Beach Bops to Alpine Anthems: Your Sonos Survival Guide for a Long Weekend Escape

Alright, fellow adventurers and relaxation enthusiasts! So, you've packed your bags, charged your devices, and mentally prepared for that glorious King's Birthday long weekend. But hold on, are you really ready? Because a true long weekend warrior kn...

Effective Commercial Pest Control Solutions for a Safer Workplace

Keeping a workplace clean, safe, and free from pests is essential for maintaining productivity, protecting employee health, and upholding a company's reputation. Pests pose health risks, can cause structural damage, and can lead to serious legal an...

The Times Features

Duke of Dural to Get Rooftop Bar as New Owners Invest in Venue Upgrade

The Duke of Dural, in Sydney’s north-west, is set for a major uplift under new ownership, following its acquisition by hospitality group Good Beer Company this week. Led by resp...

Prefab’s Second Life: Why Australia’s Backyard Boom Needs a Circular Makeover

The humble granny flat is being reimagined not just as a fix for housing shortages, but as a cornerstone of circular, factory-built architecture. But are our systems ready to s...

Melbourne’s Burglary Boom: Break-Ins Surge Nearly 25%

Victorian homeowners are being warned to act now, as rising break-ins and falling arrest rates paint a worrying picture for suburban safety. Melbourne residents are facing an ...

Exploring the Curriculum at a Modern Junior School in Melbourne

Key Highlights The curriculum at junior schools emphasises whole-person development, catering to children’s physical, emotional, and intellectual needs. It ensures early year...

Distressed by all the bad news? Here’s how to stay informed but still look after yourself

If you’re feeling like the news is particularly bad at the moment, you’re not alone. But many of us can’t look away – and don’t want to. Engaging with news can help us make ...

The Role of Your GP in Creating a Chronic Disease Management Plan That Works

Living with a long-term condition, whether that is diabetes, asthma, arthritis or heart disease, means making hundreds of small decisions every day. You plan your diet against m...