Tag: Big Bang

With the Dark Energy Spectroscopic Instrument (DESI) astronomers and physicists hope to learn something about the nature of the mysterious Dark Energy.

If you ask any astronomer or physicist what is the biggest, the most critical question, the biggest mystery in science today they will immediately reply, “What is dark Energy?” You see our observations tell us that the Universe is expanding while our theories of Gravity tell us that the expansion should be slowing down. But instead what we see is that the expansion of the Universe is accelerating. Something, some pressure is pushing the Universe ever farther apart and that ‘Dark Energy’ actually accounts for some 80-85% of all the energy in the Universe.

After the Big Bang Gravity should have caused the expansion of the Universe to at least slow down but instead something is causing to accelerate! Dark Energy! (Credit: NASA Science Mission Directorate)

The idea that we know so little about 80-85% of the Universe is more than just a bit embarrassing because since Dark Energy is the dominate part of the Universe it will obviously have the dominant effect to the eventual fate of the Universe. To understand why that is so I’m going to take a step back and review the history of the ‘Big Bang Model’ of the Universe.

One hundred years ago astronomers thought that the Universe was pretty static, neither expanding nor contracting. Physicists however didn’t like that picture because without something acting to keep the galaxies apart the force of gravity should pull everything together into a ‘Big Crunch’. Everybody was relieved therefore when the astronomer Carl Hubble found that the galaxies were in fact moving away from each other, the Universe was expanding.

The Famous image of Andromeda taken by Carl Hubble that allowed him to measure the distance and proving Andromeda was another Galaxy. (Credit: Space and Astronomy News Daily)

This was the start of the Big Bang Model where billions of years ago an incredibly dense, hot Universe expanded rapidly, cooled and then formed the galaxies we see today. The question then became whether gravity was strong enough to eventually bring the expansion to a halt, or had the Universe reached ‘escape velocity’ and the expansion would go on forever. In the first case once the Universe stopped expanding gravity would begin to cause it to contract leading to a Big Crunch. This was a known as a closed Universe. The alternative was an open Universe that would fly apart forever.

The difference between an open and closed Universe id the first expands forever while the second ends in a Big Crunch. (Credit: Astronomy Today)

The measurements needed to determine which model was correct were very difficult to make, so difficult in fact that it wasn’t until the 1990s that everyone was shocked to discover that the Universe was actually expanding faster. Something was pushing it apart and for lack of a better name that something was called Dark Energy. So we then had the biggest problem in science, what is Dark Energy?

The first thing that scientists would like to learn about Dark Energy is whether or not it is even a constant force or does it’s strength change with time? You see when Einstein formulated the equation of Gravity in his theory of general relativity, see equation below; he realized that mathematically the equation could have a constant added to it. Einstein gave that constant the symbol λ, and he calculated that the effect of that constant would look a lot like the Dark Energy we now see.

Einstein’s full equation for gravity with the cosmological constant lambda. The left hand side is the geometry of the Universe while the right hand side is the energy of the Universe. (Credit: WordPress.com)

Now if Dark Energy is just this ‘cosmological constant’ as Einstein pictured it then the expansion of the Universe will continue forever. If the strength of Dark Energy varies however, maybe even reverses itself to an attraction, then the ultimate fate of the Universe is still unknown.

However the measurements needed to determine whether the strength of Dark Energy varies with time are far more difficult to make than the measurements that discovered it in the first place. Still, astronomers have learned quite a bit in the last 25 years and advances in technology have made their instruments vastly more precise and sophisticated. It is with this improved technology that the Dark Energy Spectroscopic Instrument or DESI has been designed and constructed.

The setup of the Dark Energy Spectroscopic Instrument (DESI). New detectors and computer controlled fiber optics have been installed on the Mayall Telescope making it the most sensitive instrument for studying Dark Energy. (Credit: Spiedigitallibrary)

Retrofitted into the Mayall telescope at Kit Peak observatory outside of Tucson Arizona the DESI detector consists of a bundle of 5000 fiber optic cables, each with its own computer controlled positioning mechanism. The fiber optic cables lead to an array of 5000 spectrographs so that the combined telescope / detector will allow astronomers to accurately measure the position, magnitude and redshift of 5000 galaxies at a time. 

The DESI instrument, black object upper right, installed on the Mayall telescope. (Credit: Popular Mechanics)

First light for the DESI instrument came in September of 2019 and the ambitious five-year observation program is now well underway. Once completed the DESI will have obtained the position and redshift of 35 million galaxies allowing scientists to produce a 3D model of a large section of the Universe. This model will then provide the data needed to answer the question of whether the strength of Dark Energy has varied with time.

And there are other instruments that will soon be coming online that will compliment the observations of DESI. The 4MOST telescope at the European Southern Observatory is similar to DESI while the Euclid space telescope will also be observing galactic redshift versus distance from orbit.

The Euclid space telescope will also study the nature of Dark Energy. (Credit: Wikipedia)

 Now it is true that DESI will only tell physicists how Dark Energy changes with time nevertheless that information will be enough to enable them to eliminate many of the competing theories about its nature. So the theorists are anxiously awaiting the results of DESI and its companions, hoping that they give them direction in their effort to describe the entire Universe.

We’ve learned a great deal in the last 100 years about the structure and evolution of our Universe. I’ve little doubt that the next 100 years will bring just as many exciting discoveries.

Was there a Universe before the Big Bang? Two Researchers think they have found the evidence in the Cosmic Microwave Background (CMB).

For over fifty years now the ‘Big Bang Theory’ has been the cornerstone of our understanding of how the Universe came into being. According to the theory a little more than 13 billion years ago an incredibly dense ‘singularity’ exploded hurling matter and energy out into space (Which didn’t exist before the explosion). That matter would slowly cool to form stars and quasars and galaxies and all of the other astronomical objects we see through our telescopes today.

The strongest evidence for the Big Bang comes from observations of the Cosmic Microwave Background (CMB), literally the leftover heat from that explosion that fills all of space. The image below shows the CMB as measured by the WMAP Satellite.

The Cosmic Microwave Background as measured by the WMAP satellite (Credit: NASA)

Still, right from the very first there have been physicists and cosmologists who asked: What was going on before the Big Bang? What in fact caused the Big Bang? (Actually, since on cosmic scales time and space are pretty much the same those two questions can be combined as: What is going on outside of the Big Bang?)

Cosmologists have speculated about cyclic Universes where the expansion of the Big Bang comes to stop, leading to a collapse called a Big Crunch which then rebounds as another Big Bang starting the cycle all over again. Then they are other theories about a ‘Multi-Verse’, where our Big Bang was just one of an infinite number of Big Bangs of various sizes, shapes and properties. My favourite theory is that our Universe is just a Black Hole inside an even bigger Universe. What we call the Big Bang was the instant the Black Hole in that other Universe formed.

If you think these ideas border on crazy, well wouldn’t any theory about how our Universe began sort of have to be! The problem with all of these theories however is that the evidence needed to confirm any of them would have to have come through the Big Bang. In other words that evidence would have had to survive the unimaginable temperatures and pressures at the beginning of our Universe and few physicists thought such survival was possible.

Now however two mathematical physicists think they have found just such evidence buried within the data of the CMB. V.G. Gurzadyan of the Yerevan Physics Institute in Armenia along with Roger Penrose of The Mathematical Institute in Oxford in the UK have been working on a variation of the cyclic Universe that they call Conformal Cyclic Cosmology (CCC). In CCC each Universe, remember we’re talking about a cycle of Universes now, expands until all of the matter has spread so thin that time and space no longer really exist because there is nothing with which to measure them! The Universe has now returned to the initial condition of the Big Bang so another Big Bang occurs to start everything all over again!

One of the interesting things about CCC is that in the theory the Big Bang itself takes a little longer and is therefore less violent. Less violent enough for some traces of really powerful events, like a merger of supermassive black holes for example, to send some evidence through the Big Bang.

It would work like this, see image below. The start of a merger of two supermassive black holes would send a powerful ripple of electromagnetic and gravitational energy spreading through space and time. Once the merger is completed the ripple would cease. As the ripple spread out it would form a cone in space-time which eventually would impact on the next Big Bang causing the formation of concentric circles that could show up on the CMB.

Effect of a Black Hole Merger on a subsequent Big Bang (Credit: Penrose and Gurzadyan)

Now searching through all of the CMB data for such traces is the sort of tedious, painstaking work that only a computer could do but Penrose and Gurzadyan believe they have found some. The plots below show some of the evidence, the data peaks being the rings. The image below that shows two superimposed rings on the CMB data. (That means the rings have been artificially placed on the data as an aid to seeing them) I have to admit that I have some trouble seeing the signal through all of the noise but nevertheless I’m intrigued by the possibility of detecting ‘fossils’ of pre-Big Bang existence.

Data Plots from the WMAP Satellite data (Credit: Penrose and Gurzadyan)

Rings Superimposed on WMAP data to illustrate fossil traces from pre-Big Bang Event (Credit: Penrose and Gurzadyan)

Theories like that of Penrose and Gurzadyan are always greeted with a good deal of skepticism, as they should be. Other physicists and cosmologists will now scrutinize Penrose and Gurzadyan’s math and calculations to see if they can find any flaws. At the same time I’m certain that Penrose and Gurzadyan will be looking for more ‘fossils’, more evidence to support their claims.

If Penrose and Gurzadyan are right it would be one of the biggest finds in science in this century. Only time and more data will tell for sure.

Feathered Dinosaur Tail encased in Amber!

Remember in the movie Jurassic Park where Richard Attenborough tells Sam Neil et al that his scientists obtained Dino DNA from prehistoric mosquitoes that had been encased in amber. Well wouldn’t it be better just to have the dinosaur itself be encased in amber, or at least a part of one. Well it’s happened, a Chinese paleontologist named Xing Lida found the remarkable specimen in an amber market in northern Myanmar.

Feathered Dinosaur Tail encased in Amber

The specimen is just a portion of the tail of a very small dinosaur, and it’s covered in feathers. Now, it’s not a bird, X-rays revel that the tail bones are arranged differently than those in birds. In fact paleontologists have identified the fragment as belonging to a member of the coelurosaurian group and therefore a relative of the Mighty T-Rex and the well known velociraptors. Although this animal probably only grew to the size of a small bird.

Artists Impression of Bird sized Dinosaur

Researchers haven’t been able to obtain any DNA but they have found soft tissue and decayed blood. This specimen has already given scientists a better idea of how dinosaurs, at least some, where covered in feathers rather than scales making them better able to control their body temperature and could provide the final proof that at least some dinosaurs were warm blooded.

Looking for ordinary fossils is like looking for a needle in a haystack but trying to find such spectacular specimens in amber is certainly needle in a haystack squared. Nevertheless you can be confident that dino hunters out there will be on the lookout and before to long maybe they will find that one specimen that does give us our first actual sample of Dino DNA.

P.S. A couple of posts back I talked a little bit about Cosmic Inflation after the Big Bang and how some cosmologists, and me, think that a simpler model is to look at the Big Bang as a Big Bounce from a previously contracting Universe. Well, Nova Next from PBS just released an article which goes deeper into that very subject. If you’re as interested as I am you can check it out by clicking below.

Did the Universe Start with a Bounce Instead of a Bang?