Many people think that the model of the timeline of the Big Bang paves its way to explain a lot. And that is true! For instance, it tells us about the universe’s history and development. Moreover, the universe began as an incredibly hot and dense point.  Besides telling you some crisp information, it also tells you that the universe started around 13.7 billion years ago.

 But, here arise a question how did the universe change from being only a few millimeters in size to the immense expanse that we see today?

To make it easier to understand. Let’s break down the journey of this timeline to the present into some simple steps:

Timeline of the Big Bang – Is it a Space Exploration?

You will be very surprised to know that the Big Bang wasn’t a space explosion. Researchers clarify that it signaled the birth of space across the entire universe. As per the Big Bang theory, the universe came to exist as an incredibly hot and dense point in space.

Timeline of the Big Bang
An illustration of the timeline of the universe following the big bang. (Image credit: NASA/WMAP Science Team)

Furthermore, what happened before this moment remains unclear to cosmologists. However, using advanced space missions, ground-based telescopes, and complex calculations. Scientists have been working diligently to paint a clearer picture of the universe’s initial stages and how it formed.

Besides this, a significant part of this effort comes from studying the cosmic microwave background. This phenomenon tells us that the lingering glow of light and radiation that originates after the Big Bang. Spread throughout the universe, this can be detected by microwave instruments too. This phenomenon allows scientists to gather pieces of information about the universe’s early history, and how did the big bang happen!

The Inflation Stage – Where the Universe Timelines Underwent an Exponential Expansion!

During the universe’s early days, when it was extremely young. Around a hundredth of a billionth of a trillionth of a trillionth of a second (a really tiny fraction!). The universe went through an extraordinary phase of rapid growth. This occurrence, known as inflation, saw the universe undergo exponential expansion. Throughout this time, the universe doubled in size at least 90 times.

David Spergel is a theoretical astrophysicist at Princeton University in Princeton, N.J.. He told that after inflation, the universe continued to grow, but at a slower rate.

“The universe was expanding, and as it expanded, it got cooler and less dense.”

The Formation of Different Compounds in the Timeline of the Big Bang

In the first three minutes after the universe came into existence. Thus, the lightweight chemical elements started to form. As the universe kept expanding, the dropping temperatures led to collisions between protons and neutrons. Which results in the creation of deuterium. It is an isotope of hydrogen. A significant portion of this deuterium then combined to produce helium.

Universe Origins
WMAP has produced a new, more detailed picture of the infant universe. Colors indicate “warmer” (red) and “cooler” (blue) spots. (Image credit: NASA/WMAP Science Team)

The Phase of “Recombination”:

Around 380,000 years after the Big Bang, matter had cooled down enough for electrons to join with nuclei, creating neutral atoms. This phase is called “recombination.” The free electrons come together and made the universe become see-through. The light that was released during this period still exists today. And it is detectable radiation known as the cosmic microwave background.

After recombination, there was a dark period before stars and other bright objects appeared.

Big Bang Theory Timeline – The Dark Era!

About 400 million years after the Big Bang, the universe started to move out of the dark period. This crucial phase in the universe’s development is known as the age of re-ionization.

While it was initially thought to have taken over half a billion years, you will be surprised to know about the recent observations. They have led scientists to consider that re-ionization might have happened faster than previously believed.

During this timeline of the Big Bang, the clusters of gas came together to form the very first stars and galaxies. Besides this, the ultraviolet light emitted from these energetic events played a part in spreading out. It has cleared away most of the nearby neutral hydrogen gas.

Cosmic Microwave Background Theory – Significant Events of Universe Timeline

Astronomers are tirelessly exploring the vast reaches of the universe to find the most distant and ancient galaxies. This pursuit helps them understand how the early universe was like. Furthermore, by studying the cosmic microwave background, astronomers can effectively trace back and piece together the events that happened before.

Timeline of the Big Bang
An image taken BY NASA’s Hubble Space Telescope, showing a cluster of galaxies residing 10 billion light-years away. (Image credit: NASA/ESA/University of Florida, Gainsville/University of Missouri-Kansas City/UC Davis)

For instance, many insights gained from earlier missions like WMAP and the Cosmic Background Explorer (COBE). Both launched in 1989, as well as ongoing missions like the Hubble Space Telescope, which began its mission in 1990. They all work together to contribute to the scientific effort of solving long-standing mysteries.

The Formation of “Milky Way” in the Big Bang Timeline:

Scientists believe that our solar system formed a little more than 9 billion years after the Big Bang. Which makes it roughly 4.6 billion years old. Current calculations indicate that the sun is just one of an astonishing 100 billion stars that exist in our Milky Way galaxy. It follows a path around 25,000 light-years away from the central core of the galaxy.

NASA's Spitzer Space Telescope
An infrared view of a developing star taken by NASA’s Spitzer Space Telescope. It illustrates what our solar system might have looked like billions of years ago. (Image credit: NASA/JPL-Caltech/AURA)

Different Galaxies & Seeing of the Distant Stars:

During the 1960s and 1970s, astronomers started considering that there could be more mass in the universe than what we can see. One of these astronomers was Vera Rubin, who worked at the Carnegie Institution of Washington. She looked at how fast stars were moving at different places within galaxies.

According to basic physics by Newton, stars at the edges of a galaxy should move slower compared to stars closer to the center. However, Rubin noticed something different. She discovered that there was no change in the speeds of stars as you moved farther out from the center. In fact, she found that all stars in a galaxy appeared to be moving around the center at roughly the same speed.

Big Bang and the Universe's Origins
An illustration of Earth surrounded by filaments of dark matter called “hairs”. (Image credit: NASA/JPL-Caltech)


In the 1920s, an astronomer named Edwin Hubble made a groundbreaking discovery about the universe. Using a newly constructed telescope at the Mount Wilson Observatory in Los Angeles. Hubble revealed something transformative: the universe isn’t standing still; it’s actually getting bigger.

Fast forward to 1998, and the famous Hubble Space Telescope, named after that same pioneering astronomer. He used on studying distant exploding stars known as supernovas. Its findings brought to light a remarkable insight: a significant time in the past saw the universe expanding at a slower rate than it is today. This discovery was important because it went against earlier beliefs. Where it is defined that the gravitational pull of matter in the universe would slow down its expansion or possibly even cause it to contract.

What is the timeline of the Big Bang theory?

  • The Big Bang. 10-43 seconds.
  • The Universe Takes Shape. 10-6 seconds.
  • Formation of Basic Elements. 3 seconds.
  • The Radiation Era. 10,000 years.
  • Beginning the Era of Matter Domination. 300,000 years.
  • Birth of Stars and Galaxies. 300 million years.
  • Birth of the Sun. 5 Billion Years Before the Present (BP)
  • Earliest Life.

What are two main eras in Big Bang timeline?

Since the Big Bang, the universe has gone through several eras distinguished by the behavior of the universe’s fundamental forces and particles.

  1. Planck Era.
  2. Grand Unification Era.
  3. Electroweak Era.
  4. Elementary Particle Era.
  5. Era of Nucleosynthesis.
  6. Era of Atoms.

What are the 7 steps of the Big Bang theory?

#1 – Inflation & the Beginning

#2 – A Hot Mess & a Jumble of Particles

#3 – Cooling Cosmos & Quarks> Protons + Neutrons

#4 – Dark, Hot, and Foggy Universe (EP)

#5 – Let There Be Light & Hydrogen + Helium

#6 – Giant Clouds, Galaxies, & Stars (by He & H)

#7 – Heavy Elements In/Become Stars

What are the 5 theories of the origin of the universe?

Throughout history, people have come up with different ideas to explain things they didn’t understand. These ideas ranged from thinking the Earth was flat to believing everything revolved around us, and then realizing the Sun was at the center. Later, we learned about the Big Bang and an even faster expansion called the Inflationary Big Bang. These ideas were based on what people knew at the time. Even though they might not be completely right, we shouldn’t just call them wrong. It’s more accurate to say they were a bit imperfect because they matched what people knew back then, but they might not explain everything completely.

Dark Matter & Dark Energy!

Even as our understanding of how the universe formed and grew has expanded greatly, there are still several unanswered questions that await solutions. One of the most prominent mysteries involves the puzzling realms of dark matter and dark energy. However, cosmologists continue their efforts to explore the complexities of the universe, aiming for a more complete understanding of where it came from.

The Contribution of JWST:

A significant stride in this ongoing journey was the launch of the James Webb Space Telescope (JWST) in 2021. This advanced telescope has the goal of advancing the search to uncover the elusive properties of dark matter. Additionally, its infrared instruments did poise to look both far into the distant past and forward through the unfolding story of the universe’s evolution. This could potentially shed light on crucial aspects of how the universe originated and developed.

On Saturday,1st July at around 11:11 a.m. EDT, a new space telescope named Euclid spacecraft is ready to go to space. Let’s dive in further to know about the amazing journey of this spacecraft;

What the Euclid spacecraft actually is?

It is a European Space Agency (ESA) project, but NASA, the American space agency, also helped a lot. Its main job is to discover why the universe is getting bigger faster and faster. Scientists are curious about the strange force causing this, calling it “dark energy.”

Two of the greatest contemporary enigmas about the cosmos, dark matter and dark energy, will be clarified by the ESA project Euclid spacecraft, to which NASA will also contribute.

Nancy Grace Telescope collaborating with Euclid spacecraft

By May 2027, another NASA telescope called the Nancy Grace Roman Space Telescope will team up with Euclid. Together, they will try to solve this mystery in new ways. Jason Rhodes, a top research scientist at NASA’s Jet Propulsion Laboratory in Southern California and a key person in both the Roman and Euclid spacecraft projects, said that;

“Even though we learned about the universe’s fast expansion 25 years ago, we still don’t understand it”.

He said;

“These new telescopes would help us measure dark energy much better than before, starting a new exploration period.”

Scientists are curious to know if the universe’s speedy expansion is because of some extra energy or if it means that we need to change how we understand gravity. Astronomers will use Roman and Euclid to look into both of these theories. They think both of these projects will give us important information about the universe’s workings.

How will the Roman and Euclid will work?

Euclid and Roman are made to study the universe’s speedy expansion, but they’ll do it in different ways that complement each other. Both will make 3D maps of the universe to answer big questions about its history and structure. Together, they’ll be much more powerful than they would be alone.

Euclid spacecraft will look at a much bigger area of the sky – around 15,000 square degrees, or about a third – using infrared and optical light but will see less detail than Roman. It will look back 10 billion years to when the universe was about 3 billion years old.

Roman can look at the universe with more detail and precision but will cover a smaller area – about 2,000 square degrees, or one-twentieth of the sky. Its infrared vision will see the universe when it was 2 billion years old, showing more fainter galaxies. While Euclid spacecraft will only look at the universe’s structure, Roman will also study closer galaxies, find and study planets throughout our galaxy, look at objects at the edges of our solar system, and much more.

Some crucial aspects of the ESA's Euclid and NASA's Roman spacecraft are compared in this infographic.

The Hunt for Dark Energy

The universe has grown since it was born, a fact discovered by Belgian astronomer Georges Lemaître in 1927 and Edwin Hubble in 1929. But scientists thought that the universe’s gravity would gradually slow this growth. In the 1990s, by looking at a specific kind of supernova, scientists found out that about 6 billion years ago, dark energy started to have a bigger effect on the universe, and we don’t know how or why. The fact that the universe’s expansion is speeding up means that we don’t understand something about the universe.

What will Euclid and Roman projects will study?

Roman and Euclid will give us new data to help us understand this mystery. They’ll try to figure out what’s causing the universe’s speedy expansion in a few different ways. First, Roman and Euclid will look at how matter has accumulated over time using weak gravitational lensing. This happens because anything with mass bends space-time; the more mass, the more bending. The light that moves through these bends looks distorted. The background can look smeared or show multiple images when the bending objects are big galaxies or clusters of galaxies.

Less concentrated mass, like clumps of dark matter, can create smaller effects. Roman and Euclid spacecraft will create a 3D map of dark matter by studying these smaller distortions. This will give clues about the universe’s speedy expansion because the gravitational pull of dark matter, acting like a glue that holds galaxies and galaxy clusters together, fights against the universe’s expansion. By counting all the universe’s dark matter over time, scientists will better understand the push-and-pull causing the universe’s speedy expansion.

The two projects will also study how galaxies are grouped at different times in the universe. Scientists have seen a pattern in how galaxies gather from measurements of the nearby universe. For any galaxy today, we are about twice as likely to find another galaxy about 500 million light-years away than a little nearer or farther.

Observing the Expansion of universe

This distance has grown over time because of the universe’s expansion. By looking further into the universe via Euclid spacecraft, to earlier times, astronomers can study the preferred distance between galaxies in different periods. Seeing how it has changed will reveal the universe’s expansion history. Seeing how galaxy grouping varies over time will also allow a precise gravity test. This will help astronomers tell the difference between an unknown energy component and different theories about modified gravity as explanations for the universe’s speedy expansion.

Roman’s survey for Ia supernova

Apart from Euclid spacecraft, Roman will conduct an extra survey to discover many faraway type Ia supernovae – a special exploding star. These explosions have a similar brightness. Because of this, astronomers can determine how far away the supernovae are by measuring how bright they look.

Astronomers will use Roman to study the light of these supernovae to find out how fast they appear to be moving away from us. Scientists will trace the universe’s expansion over time by comparing how fast they’re moving away at different distances. This will help us better understand whether and how dark energy has changed throughout the universe’s history.

What is the significance of Roman and Euclid spacecraft project?

The two projects’ surveys will overlap, with Euclid likely looking at the entire area Roman will examine. Scientists can use Roman’s more detailed and precise data to correct Euclid’s and apply these corrections to Euclid’s larger area.

Mike Seiffert, a project scientist for the NASA contribution to Euclid at NASA’s Jet Propulsion Laboratory, said that Euclid spacecraft’s first look at the big area of sky it will study would inform the science, analysis, and survey approach for Roman’s more detailed examination.

Yun Wang, a senior research scientist at Caltech/IPAC in Pasadena, California, who has led galaxy grouping science groups for both Euclid and Roman, said,

“Together, Euclid and Roman will add up to much more than the sum of their parts.”

He said combining their observations will give astronomers a better idea of what’s happening in the universe.

Three science groups supported by NASA are contributing to the Euclid spacecraft project. Along with designing and making Euclid’s Near Infrared Spectrometer and Photometer (NISP) instrument sensor-chip electronics, JPL led the getting and delivery of the NISP detectors. NASA’s Goddard Space Flight Center tested those detectors. The Euclid NASA Science Center at IPAC (ENSCI) at Caltech will support U.S.-based studies using Euclid spacecraft data


Cosmic Distance Ladder

IA supernovae following which, Einstein Cross occured, play a crucial role. And measuring the vast distances of the cosmos poses a significant challenge for astronomers, who employ various methods and tools collectively known as the cosmic distance ladder. These supernovae occur in binary systems where a white dwarf star feeds on matter from its companion, often a red giant until it surpasses the Chandrasekhar limit and collapses due to its mass. These stars shed their outer layers in a massive explosion, temporarily outshining everything else in their surroundings.

In a recent study, an international team of researchers led by Ariel Goobar from the Oskar Klein Centre at Stockholm University made an extraordinary discovery: an uncommon type IA supernova named SN Zwicky (SN 2022qmx).

Einstein Cross
Illustration of a “type Ia” supernova. When the white dwarf reaches an estimated 1.4 times the current mass of the Sun, it can no longer sustain its weight and collapses. (NASA/JPL-Caltech)

Unveiling Einstein Ring or Einstein Cross

What made this discovery even more astonishing was the discovery of the Einstein ring, somehow, also reffered as Einstein Cross, a unique phenomenon predicted by Einstein’s general theory of relativity. This phenomenon occurs when the gravitational lensing effect generated by a foreground object enhances the light emitted by a distant object.

The team’s achievement was significant because it involved the observation of two exceedingly rare astronomical events that coincided.

Researchers from the Oskar Klein Centre, the Kavli Institute for Cosmology, the Cahill Center for Astrophysics, the Infrared Processing and Analysis Center (IPAC), the Ecole Polytechnique Fédérale de Lausanne (EPFL), the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), the Centre de Recherche Astrophysique de Lyon, NASA Goddard, the Space Telescope Science Institute (STScI), and multiple universities made up the team. Their research paper describing these findings was recently published in Nature Astronomy.

Einstein Cross
Imaging of the field of SN Zwicky using multiple sources. (Goobar et al., Nature Astronomy, 2023)

SN Zwicky and Einstein Ring

Initially, the Zwicky Transient Facility at the Palomar Observatory in California detected the supernova. The facility was named after astronomer Fritz Zwicky, who proposed the possibility of dark matter in the 1930s. Several weeks later, the team employed adaptive optics (AO) at the W.M. Keck Observatory in Hawaii and the Very Large Telescope (VLT) at the Paranal Observatory in Chile to observe SN Zwicky. Goobar and his colleagues hypothesized that they were witnessing a solid lensing effect based on the observed brightness. Further observations and images obtained by the Hubble Space Telescope confirmed this hypothesis, revealing that the multiple-image lensing effect was a result of a galaxy in the foreground that magnified the supernova by 25 times!

Studying Mysteries of Einstein Cross

This fortunate discovery of Einstein Cross opens up numerous opportunities for astronomers, enabling them to study SN Zwicky in greater detail and delve deeper into the mysteries of gravitational lenses. As Goobar expressed in a press release from Stockholm University,

“The discovery of SN Zwicky not only showcases the remarkable capabilities of modern astronomical instruments but also represents a significant step forward in our quest to understand the fundamental forces shaping our Universe.” However, the implications extend beyond these two phenomena. The study of type Ia supernovae led astronomers to the groundbreaking realization that the expansion of the cosmos is accelerating.

Universe’s Acceleration Expanding

This discovery of Einstein Cross earned the 2011 Nobel Prize in Physics, which was divided between Saul Perlmutter (The Supernova Cosmology Project) and jointly awarded to Brian P. Schmidt and Adam G. Reiss (The High-z Supernova Search Team). Consequently, observations of SN Zwicky could contribute to unraveling the mystery behind this accelerated expansion. Joel Johansson, a co-author of the study and a postdoctoral fellow at Stockholm University, highlighted the significance of SN Zwicky’s extreme magnification, stating,

Implications and Insights from SN Zwicky Discovery

“The extreme magnification of SN Zwicky gives us an unprecedented chance to study the properties of distant type IA supernova explosions, which we need when we use them to explore the nature of dark energy.”

Furthermore, the discovery of Einstein Cross could throw light on the cryptic nature of dark matter and provide insights into speculations regarding the Universe’s ultimate fate, such as the Big Crunch, Big Rip, or Heat Death.

Scientists have discovered that dark energy, the unknown force causing the universe to expand faster and faster, is evenly distributed throughout space and time. The study team stated that their findings help us understand how much of the universe’s energy and matter content is made up of dark energy. 

What is the eROSITA X-ray instrument?

Scientists used the eROSITA X-ray instrument to study galaxy clusters. This tool scans the entire sky from Earth to find groups of galaxies. After analyzing their observations, the scientists came to their conclusions. In 2019, a space telescope called Spektr-RG was launched into Earth’s orbit. It has a tool called eROSITA attached to it, which was made by both Russian and German scientists.

How Galaxy cluster helps us understand dark energy?

Galaxy clusters can help us understand dark energy. Dark energy is a strange force that works against gravity and stops huge structures from forming in space. By studying galaxy clusters, we can learn more about this mysterious force. Dark energy decides where and how the biggest objects in the universe, called galaxy clusters, can come into existence. 

Matthias Klein:

Counting the number of galaxy clusters formed in the universe over time can teach us a lot about dark energy, according to astrophysicist Matthias Klein from Ludwig-Maximillians-Universitat Munchen in Germany.

What is the eROSITA Final Equatorial-Depth Survey (eFEDS), and what did it discover?

Scientists found around 500 galaxy clusters through the eROSITA Final Equatorial-Depth Survey (eFEDS). This is one of the biggest collections of low-mass galaxy clusters that have been discovered so far. We have observed clusters that span the last 10 billion years of the universe’s 13.8 billion-year history.

The researchers used information from eROSITA and Hyper Suprime-Cam Subaru Strategic Program to conduct their study. Thanks to eROSITA, we were able to conduct the first-ever study of the universe’s structure using galaxy clusters.

How did the researchers compare their study’s results to predictions, and what did they find?

Scientists compared the study’s results to their predictions and found that dark energy makes up about 76% of the universe’s total energy. The research shows that the amount of energy in a given space is the same everywhere and doesn’t change over time. 

The team’s findings match up with other ways of studying dark energy, like looking at galaxy clusters and how gravity affects light. Although the new discoveries provide more information about dark energy, physicists are still curious to uncover the mystery behind this force. 

What makes dark energy a problem?

In the 1920s, an astronomer named Edwin Hubble looked at faraway galaxies and saw that they were moving away from us. Scientists discovered that the universe is expanding because galaxies that are farther away are moving away faster.

This was surprising because it challenged the widely accepted belief that the universe was unchanging and constant. In 1998, scientists discovered something strange. They found out that the universe is not only expanding, but it’s also getting bigger faster and faster. They learned this by studying faraway exploding stars. 

What is dark energy and how is it affecting the universe?

An astrophysicist named Joe Mohr explained that there is something called “dark energy” that causes the universe to expand faster. It’s like an opposite force to gravity.

Scientists know that dark energy makes up about 76% of the energy and matter in the universe, but they still don’t know what it is or why it started affecting the universe later on.

How does dark energy impact the expansion of the universe over time?

Dark energy causes the universe to expand faster as time goes on, similar to how a child swings more quickly after an initial push. This happens after the initial rapid expansion from the Big Bang. When the child stops swinging, the swing starts moving again on its own. It not only speeds up quickly, but it also goes higher and higher. 

Why is the study of dark energy necessary for our understanding of the cosmos?

Scientists use the swing analogy to explain that the accelerating expansion of the universe means that they are missing something important in their understanding of the cosmos.

Mohr explained that while there are still some mistakes in our understanding of dark energy, this study used a small portion of the sky called eFEDS, which is less than 1% of the entire sky. Scientists are trying to figure out what dark energy is and it could be a big discovery that wins a Nobel Prize.

It has taken decades of research for scientists to even begin to understand where Mysterious dark energy comes from. The rapid expansion of the cosmos suggests that some force is overpowering gravity, which should slow things down. Even though dark energy has been proposed as the source of that power, its origin has remained a mystery.

The collective study:

However, a group of 17 researchers from around the world, directed by scientists from the University of Hawaii, have found the first evidence that black holes are the source of Mysterious dark energy.

Black holes gain mass through either the accretion of gas or the merger with other black holes. In contrast, the older black holes are far larger than they should be based on growth by either of these two mechanisms, as determined by researching the history of black holes over nine billion years in dormant huge elliptical galaxies. So, these black holes must be gaining mass in some other way. Scientists think the answer lies in a sort of dark energy known as vacuum energy. According to a statement: “a kind of energy included in spacetime itself … [that] pushes the universe further apart, accelerating the expansion,”.

Dr. Chris Pearson:

As one of the study’s co-authors, Dr. Chris Pearson of STFC RAL Space elaborated on the findings in a press release. He says: “If the theory holds, then this is going to revolutionize the whole of cosmology because at last, we’ve got a solution for the origin of dark energy that’s been perplexing cosmologists and theoretical physicists for more than 20 years,”

Einstein’s theory of general relativity:

This concept of black holes as sources of Mysterious dark energy is not new. Einstein put it into his theory of general relativity. It’s the first time astronomers have had observational evidence to back up the notion.

Duncan Farah:

Astronomer Duncan Farah of the University of Hawaii says: “We’re saying two things at once: That there’s evidence the typical black hole solutions don’t work for you on a long, long timescale, and we have the first proposed astrophysical source for dark energy.”


Published by: Sky Headlines