Cosmology Archive

Einstein and the Event Horizon Telescope

Posted March 5, 2017 By admin

Black Holes are both awe inspiring and endlessly fascinating. Who can fail to be interested in a place where time and light die? They are places of unimaginable power, where the laws of nature as we understand them break down.

And what intrigues me more than anything about black holes is that all we know about them is purely man made. What do I mean; after all, surely, there is nothing less man made than such exotic beasts? Yet all we know about them comes from the human mind and imagination because we have never actually seen one let alone probed or examined one.

Black Holes are the creation of Albert Einstein’s General Theory of Relativity (GTR). Without the theory it would be impossible to have created the concept of the black hole. The GTR predicts that if mass is sufficiently compacted it can deform space-time and create black holes. So what are the features of black holes? A brief summary goes like this:

  • The pulling force of a black hole is so great that not even light can escape – hence the term – black hole. It consumes everything within its gravity. There is no escape.
  • Such enormous gravity is caused by matter being squeezed into a tiny space, such as when stars die and collapse in on themselves
  • There are a whole range of sizes, from the small primordial black holes that are thought to have formed when the universe was formed, to super massive black holes at the centre of galaxies, which have the mass of more than a million times our sun in a space the size of the solar system.
  • The black hole at the centre of our galaxy is called Sagittarius A.
  • We have not seen a black hole – yet, we know of their existence by theory and through stars orbiting close to one producing high-energy light, which we can observe.

However, for the first time it is proposed that we will be able to observe a black hole and take a picture. It is some picture though and it will be taken by the Event Horizon Telescope (EHT).

The EHT is not one stand alone telescope. It is a network of radio telescopes dotted around the globe and it is about to go operational. It plans to focus on the super massive black hole Sagittarius A at the centre of our Galaxy, which is 25000 light years away. The nine telescopes create a virtual telescope the size of the earth by combining data from them all and is capable of seeing a grapefruit on the moon.

What will be seen? Well if GTR is correct a crescent of clouds of dust and gas which blazes with energy. Indeed, the picture will be a validation test for GTR. If the picture sees a ring, then there is something incorrect in the GTR, it predicts a crescent.

All I can say is that every validation so far has proved the theory correct, so I look forward to success. And imagine the excitement of seeing a picture of a black hole!

The EHT is a true Einstein machine. An earth wide network designed to see what the GTR predicted and which will further validate the theory.

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Einstein Special – Scientific American

Posted September 27, 2015 By admin

As I have written about several times this year, 2015 marks the 100th anniversary of the first publication of The General Theory of Relativity and, as expected, the books and articles are coming thick and fast.

 

The latest contribution is a Scientific American special Issue: 100 years of General Relativity. Contributors include Brian Greene, Walter Isaacson, Lawrence Krauss and Corey S, Powell. There are familiar subjects: essays about the history of the publication, his importance, his personality and his mistakes. However, one article in particular caught my attention. It is called Relativity’s Reach and contains a map of Einstein’s influence. It’s premise is that many of the ideas at the limits of physics, such as M-theory and de Sitter universes rely on Einstein’s masterwork on gravity and the bending of space and time.

 

The article relies on the analysis of 2435 abstracts of 2014 physics papers for 61 keywords, each of which represents a research topic that has grown out of general relativity, which is then visually represented.. It leads to a visually interesting map and reveals the depths to which Einstein’s work influences current ideas at the cutting edge of physics. And remember, this is just his work on General relativity; it doesn’t touch his work on Quantum Theory and Special relativity.

 

For a complete list of the current works that Einstein’s work is the cornerstone for, you will need to see the article, but it includes: multiverse, accelerating universe, standard model, supersymmetry, cosmology, string theory, quantum gravity, dark matter and gravitational waves.

 

Einstein’s influence remains deep and persuasive. It not only underpins much of our daily lives through technology, but also the ideas at the very edge of our understanding about the universe and the world in which we live.

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Whispers of the Big Bang?

Posted March 16, 2014 By admin

There are rumours that an American Astrophysics team are set to announce they have detected primordial gravitational waves, which are in essence an echo of the big bang. If correct it will be one of those big physics headlines, much like the announcement of the Higgs-boson.

The signal is rumoured to have been found by a telescope called bicep (Background Imaging of Cosmic Extragalactic Polarization) at the South Pole. It scans the sky at microwave frequencies, where it picks up the fossil energy from the big bang.

What are gravitational waves? Follow the link for a full explanation, but in brief they are tiny ripples in the fabric of space/time that carry energy across space.

And what have they to do with Albert Einstein you ask? Well everything really because they are the last untested prediction of the General Theory of Relativity. To date there has not been any direct detection of them. If the rumours are correct and the team have detected them, then not only will it be further proof (if any is needed) of the correctness of GTR, but also will provide invaluable insights into the first moments of the Big Bang. It has been described as one of the Holy grails of Cosmology and would be ranked as one of the most important discoveries of our time.

Once more Albert Einstein and his predictions are in the news as his work continues to explain our universe and our understanding of it.

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Einstein’s accuracy

Posted May 13, 2012 By admin

There has been further experimental evidence proving the incrediable accuracy of Albert Einstein’s General Theory of Relativity. A team of cosmologists have announced at the National Astronomy Meeting being held at the University of Manchester, the most accurate measurement ever made from when the expansion of the universe began to accelerate.

It means that the phenomenon can be explained using just Einstein’s general theory of relativity and the cosmological constant – the simplest theoretical explanation for the acceleration of the universe. The results will be used to understand what is causing the acceleration and why, and will shed new light on dark energy – the name adopted for the fundamental agent driving the acceleration about which little is known.

The cosmologists from the University of Portsmouth and the Max Planck Institute for Extraterrestrial Physics have examined the period between five and six billion years ago when the universe was almost half its present age and made measurements of extraordinary accuracy – within 1.7 per cent. The findings support Einstein’s general theory of relativity which predicts how fast galaxies, separated by large distances, should be moving toward one another and at what rate the structure of the universe should be growing.

Team member Dr Rita Tojeiro said: ”The results are the best measurement of an intergalactic distance ever made, which means cosmologists are closer than ever to understanding why the universe’s expansion is accelerating. One of the great things about Einstein’s general theory of relativity is that it is testable. Our results support the theory and are fully consistent with the notion that constant vacuum energy – empty space creating a repulsive force – is driving the acceleration of the universe. These are profound statements that describe the physics of our universe at the most fundamental level. Critically, the results find no evidence that dark energy is simply an illusion stemming from our poor understanding of the laws of gravity – Einstein’s theory has passed its most stringent test yet at extra-galactic scales.”

The new discoveries are based on work by a collaboration of astronomers from across the globe representing the Baryon Acoustic Oscillation Spectroscopic Survey (BOSS), part of the third Sloan Digital Sky Survey (SDSS-III), which is mapping the three-dimensional positions of more than one million galaxies.

Once again Einstein has proved the durability of his theories. Despite recent concerns about the limits of the speed of light being the ultimate universal speed limit, evidence is mounting that Einstein was right after all and the results of these experiments prove just how fundamental and important Einstein’s theory of relativity is for our understanding of the universe

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Was Einstein Wrong?

Posted October 31, 2010 By admin

On Friday 29th October 2010, New Zealand’s national radio host Kathryn Ryan interviewed New Zealand born Professor Warrick Couch, who in 1998 was one of the team of cosmologists to discover that the rate of expansion in the universe is speeding up, not slowing down, in contradiction to Einstein’s General Theory of Relativity.

Listen to the full interview.

The interview traverses a number of topics including

1. The apparent contradiction in the expanding universe and Einstein’s General Theory of Relativity,

2. Einstein’s mistake in using the cosmological constant,

3. A philosophical discussion on faith and science,

4. The meaning of the multiverse.

This is a most enjoyable interview of a man who has greatly contributed to our idea of the Universe.

For more discussion on the importance of Einstein’s great theory see my posts on the General Theory of Relativity.

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