Lambda CDM Archives

March 1, 2020March 1, 2020 by Matt Williams

What is the Steady State Hypothesis?

Artist's impression of the Milky Way Galaxy. Credit: ESO

When it comes to our cosmic origins, a number of theories have been advanced throughout the course of history. Literally every culture that’s ever existed has had its own mythological tradition, which naturally included a creation story. With the birth of the scientific tradition, scientists began to understand the Universe in terms of physical laws that could be tested and proven.

With the dawn of the Space Age, scientists began testing cosmological theories in terms of observable phenomena. From all of this, a number of theories emerged by the latter half of the 20th century that attempted to explain how all matter and the physical laws governing it came to be. Of these, the Big Bang Theory remains the most widely accepted while the Steady-State Hypothesis has historically been its greatest challenger.

February 13, 2020February 13, 2020 by Matt Williams

Astronomers Simulated How the Universe Would Look Without Dark Matter

Since the 1960s, there has been a general consensus among astronomers and cosmologists that the majority of the Universe is made up of an invisible, mysterious mass (known as Dark Matter). While scientists still haven’t identified the candidate particle that makes up this mass, indirect tests and simulations have shown that Dark Matter must exist in order for the Universe to be the way it is.

In a fascinating twist, a team of European researchers conducted a simulation that looked at a Universe without Dark Matter. Using an alternative theory known as MOdified Newtonian Dynamics (MOND), the team created a computer simulation in which the galaxies were actually very similar to what we see in the Universe today. These findings could help to resolve one of the most enduring mysteries of modern cosmology.

September 20, 2018September 20, 2018 by Matt Williams

Narrowing Down the Mass of the Milky Way

Using information from Gaia's second data release, a team of scientists have made refined estimates of the Milky Way's mass. Credit: ESA/Gaia/DPAC

Since the birth of modern astronomy, scientists have sought to determine the full extent of the Milky Way galaxy and learn more about its structure, formation and evolution. At present, astronomers estimate that it is 100,000 to 180,000 light-years in diameter and consists of 100 to 400 billion stars – though some estimates say there could be as many as 1 trillion.

And yet, even after decades of research and observations, there is still much about our galaxy astronomers do not know. For example, they are still trying to determine how massive the Milky Way is, and estimates vary widely. In a new study, a team of international scientists presents a new method for weighing the galaxy based the dynamics of the Milky Way’s satellites galaxies.

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September 8, 2018February 8, 2023 by Matt Williams

What is the Cosmic Microwave Background?

This single all-sky image, captured by the Planck telescope, simultaneously captured two snapshots that straddle virtually the entire 13.7 billion year history of the universe. Credit: ESA

For thousands of years, human being have been contemplating the Universe and seeking to determine its true extent. And whereas ancient philosophers believed that the world consisted of a disk, a ziggurat or a cube surrounded by celestial oceans or some kind of ether, the development of modern astronomy opened their eyes to new frontiers. By the 20th century, scientists began to understand just how vast (and maybe even unending) the Universe really is.

And in the course of looking farther out into space, and deeper back in time, cosmologists have discovered some truly amazing things. For example, during the 1960s, astronomers became aware of microwave background radiation that was detectable in all directions. Known as the Cosmic Microwave Background (CMB), the existence of this radiation has helped to inform our understanding of how the Universe began. Continue reading “What is the Cosmic Microwave Background?”

May 15, 2018February 8, 2023 by Matt Williams

If There is a Multiverse, Can There be Life There Too?

*Could our Universe be part of a wider Multiverse? And could these other Universes support life? Credit: Jaime Salcido/EAGLE Collaboration*

The Multiverse Theory, which states that there may be multiple or even an infinite number of Universes, is a time-honored concept in cosmology and theoretical physics. While the term goes back to the late 19th century, the scientific basis of this theory arose from quantum physics and the study of cosmological forces like black holes, singularities, and problems arising out of the Big Bang Theory.

One of the most burning questions when it comes to this theory is whether or not life could exist in multiple Universes. If indeed the laws of physics change from one Universe to the next, what could this mean for life itself? According to a new series of studies by a team of international researchers, it is possible that life could be common throughout the Multiverse (if it actually exists).

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December 8, 2016February 8, 2023 by Matt Williams

ESO Survey Shows Dark Matter to be Pretty “Smooth”

The technique of gravitational lensing relies on the presence of a large cluster of matter between the observer and the object to magnify light coming from that object. Credit: NASA

Dark Matter has been something of a mystery ever since it was first proposed. In addition to trying to find some direct evidence of its existence, scientists have also spent the past few decades developing theoretical models to explain how it works. In recent years, the popular conception has been that Dark Matter is “cold”, and distributed in clumps throughout the Universe, an observation supported by the Planck mission data.

However, a new study produced by an international team of researchers paints a different picture. Using data from the Kilo Degree Survey (KiDS), these researchers studied how the light coming from millions of distant galaxies was affected by the gravitational influence of matter on the largest of scales. What they found was that Dark Matter appears to more smoothly distributed throughout space than previously thought.

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August 30, 2016February 8, 2023 by Matt Williams

Dark Matter: Hot Or Not?

Illustris simulation, showing the distribution of dark matter in 350 million by 300,000 light years. Galaxies are shown as high-density white dots (left) and as normal, baryonic matter (right). Credit: Markus Haider/Illustris

For almost a century, astronomers and cosmologists have postulated that space is filled with an invisible mass known as “dark matter”. Accounting for 27% of the mass and energy in the observable universe, the existence of this matter was intended to explain all the “missing” baryonic matter in cosmological models. Unfortunately, the concept of dark matter has solved one cosmological problem, only to create another.

If this matter does exist, what is it made of? So far, theories have ranged from saying that it is made up of cold, warm or hot matter, with the most widely-accepted theory being the Lambda Cold Dark Matter (Lambda-CDM) model. However, a new study produced by a team of European astronomer suggests that the Warm Dark Matter (WDM) model may be able to explain the latest observations made of the early Universe.

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May 15, 2016May 15, 2016 by Matt Williams

Japanese 3D Galaxy Map Confirms Einstein Was One Smart Dude

An international team of researchers have produced the largest 3-D map of the universe to date, which validates Einstein's theory of General Relativity. Credit: NAOJ/CFHT/ SDSS

On June 30th, 1905, Albert Einstein started a revolution with the publication of theory of Special Relativity. This theory, among other things, stated that the speed of light in a vacuum is the same for all observers, regardless of the source. In 1915, he followed this up with the publication of his theory of General Relativity, which asserted that gravity has a warping effect on space-time. For over a century, these theories have been an essential tool in astrophysics, explaining the behavior of the Universe on the large scale.

However, since the 1990s, astronomers have been aware of the fact that the Universe is expanding at an accelerated rate. In an effort to explain the mechanics behind this, suggestions have ranged from the possible existence of an invisible energy (i.e. Dark Energy) to the possibility that Einstein’s field equations of General Relativity could be breaking down. But thanks to the recent work of an international research team, it is now known that Einstein had it right all along.

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December 17, 2015February 8, 2023 by Matt Williams

Big Bang Theory: Evolution of Our Universe

Illustration of the Big Bang Theory — The Big Bang Theory: A history of the Universe starting from a singularity and expanding ever since. Credit: grandunificationtheory.com

How was our Universe created? How did it come to be the seemingly infinite place we know of today? And what will become of it, ages from now? These are the questions that have been puzzling philosophers and scholars since the beginning the time, and led to some pretty wild and interesting theories. Today, the consensus among scientists, astronomers and cosmologists is that the Universe as we know it was created in a massive explosion that not only created the majority of matter, but the physical laws that govern our ever-expanding cosmos. This is known as The Big Bang Theory.

For almost a century, the term has been bandied about by scholars and non-scholars alike. This should come as no surprise, seeing as how it is the most accepted theory of our origins. But what exactly does it mean? How was our Universe conceived in a massive explosion, what proof is there of this, and what does the theory say about the long-term projections for our Universe?

The basics of the Big Bang theory are fairly simple. In short, the Big Bang hypothesis states that all of the current and past matter in the Universe came into existence at the same time, roughly 13.8 billion years ago. At this time, all matter was compacted into a very small ball with infinite density and intense heat called a Singularity. Suddenly, the Singularity began expanding, and the universe as we know it began.

October 29, 2011February 8, 2023 by Steve Nerlich

Astronomy Without A Telescope – Dark Matter Science

Dark matter has been found to be (unexpectedly) evenly distributed across dwarf galaxies, rather than clumping together in the centre - in the way we that we had expected of 'cold' dark matter.

Dark matter – there’s a growing feeling that we are getting closer to finding out the true nature of this elusive stuff. At least we are running a number of experiments that seem (on theoretical grounds) to have the capacity to identify it – and if they don’t… well, maybe it’s time for a rethink of the whole ball game.

There are two arguably quite separate requirements for dark matter to make sense of our current dataset and our theoretical schema for the universe. Firstly, the Standard Model of cosmology (Lambda-Cold Dark Matter) requires that 96% of the universe is composed of stuff of an unknown nature that cannot be directly observed.

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