My name is Rhodri Evans. I grew up in south-west Wales, in the beautiful peninsula called Pembrokeshire. The entire Pembrokeshire coastline is a national park with stunning beaches and high cliffs.
Taken at a social evening for my running club in Penarth, South Wales (July 2013)
I have a PhD in astrophysics; my main research areas being Airborne Astronomy using NASA’s Stratospheric Observatory For Infrared Astronomy (SOFIA), and the Africa Millimetre Telescope. Since March 2017 I have been a senior lecturer at the University of Namibia; I lecture in astrophysics, physics and maths, and I am also a frequent contributor on astronomy and physics to radio and TV. I have talked on the BBC, S4C and ITV in the United Kingdom; and CBS, C-SPAN, ABC and PBS in the United States. I have given talks at conferences and astronomical societies around the World. I have also written several books, details can be found here.
Having decided not to apply to Oxford or Cambridge, I obtained a BSc with 1st class honours in Physics from Imperial College London, consistently rated the best Physics department in the United Kingdom. I obtained my PhD in Astrophysics from Cardiff University, my thesis was on the amount and extent of dust in normal spiral galaxies. I have worked as a post-doctoral researcher at the University of Chicago and was a Professor of Physics and Astrophysics at Swarthmore College, one of the top rated 4-year undergraduate liberal arts colleges in the USA. I left the USA in 2001 to return to work at Cardiff University, but in 2017 I moved to Namibia (in south-west Africa), to be part of a project to build Africa’s first millimetre-wave telescope.
Mount Gamsberg (2,400m elevation) with the SEST-mm-wave telescope superimposed
I have a wide range of interests outside of astrophysics; including science in general, music, sport (particularly rugby, running, tennis and football), photography, movies, reading and politics. I will try to update this blog 3-4 times a week with random thoughts about life, the Universe, or anything.
made my way to your website from bing and and am glad i found it, hope you keep up the good work
Thank you. I hope you continue to read it.
Hi Where is the beautiful landscape in your header?
It’s a place called Y Rhigos in South Wales, not far from Cardiff.
Greetings,
Did the Big Bang occur at a single point ?
The light is said to have left this galaxy some 500 million years after the big bang – fine.
The galaxy therefore must have been no further than 500 million light years from the point of the big bang since it could not have traveled faster than the speed of light (according to the theory of relativity).
Assuming that the galaxy moved in a direction diametrically opposite to the direction that “we” moved after the big bang, “we” would be 13.2-0.5=12.7 billion light years from the point where Big Bang occurred (assuming that it did indeed occur at a single point).
Now, since the Big Bang occurred 13.7 billion years ago & happened at a point 12.7 billion light years away, “we” would have to have traveled a minimum of 12.7 billion light years in “our” 13.7 billion year existence.
“Our” average speed for this “flight” would have to be some 93% of the speed of light !!!!
So, is it really true that “we” have been traveling at an average speed of 93% of the speed of light since the Big Bang ?
Or is there some other explanation for this anomaly ?
The Big Bang was the creation of the Universe. At the moment of the Big Bang, the Universe was a single point. Since then the Universe has been expanding. If we are seeing light from a galaxy when the Universe was 500 million years old then, if the Big Bang occurred 13.7 billion years ago, then the light has taken 13.7-0.5=13.2 billion years to reach us. There is no anomaly.
My question is simple & clear – We are a minimum 12.7 billion light years away from the Big Bang. Have we really traveled this far ? If so, our average speed would have to be about of 93% of the speed of light.
You are thinking about it incorrectly. We are NOT 12.7 billion light years away from the Big Bang. The Big Bang happened 13.7 billion years ago, but it happened EVERYWHERE because at the moment of the Big Bang the Universe was infinitesimally small. We are not moving away from some point where the Big Bang happened.
@Naveen: Several comments. First, “occurred at a single point” is, at best, misleading. Second, special relativity doesn’t provide the constraint here that you think it does. Third, there are several distances in cosmology, which in general are all distinct. Unless you specify which distances you mean, there is no point in putting in the numbers. I highly recommend the book Cosmology: The Science of the Universe by Edward R. Harrison. It is a textbook which is aimed at the non-cosmologist (it grew out of an “astronomy for poets” lecture) but at the same time doesn’t skimp on technical details while nevertheless remaining accessible.
The Hubble Extreme Deep Field image which quotes a galaxy seen 500 million years after the Big Bang does not say how this distance was determined. My suspicion, given that the image has only just been released, is that this distance is based on photometric redshift, not even actual Doppler redshift. Of course, to gain an idea of its actual distance one would need to use a standard candle. And, as you say Phillip, the “distance” depends on how you define distance.
I did not plan to go into technical details @Naveen, but there is a common misconception that nothing can travel faster than the speed of light. In fact, space can expand faster than the speed of light. We are fairly sure, if you believe in inflation, that the Universe did this during its period of inflation. But, there is no need for superluminal expansion to be able to see a galaxy 13.2 billion light years away.
Hi! Drifted to your blog from a Google image search of particle tracks… I’m a PhD candidate in Aerospace engg and lived in Palmdale, CA for a year which is where SOFIA lives too 🙂 Glad to see you’re in the same field. It’s a great project! One of my neighbours was a German from DLR working on loan to NASA with SOFIA.
I am glad you’ve found your way to my little corner of the internet. Welcome!
Hi Rhodri, hard luck in the rugby at the weekend I watched the game sadly things didn’t go your way. Apart from Ireland, I have always loved and admired the passion and heart Wales bring to the game of rugby, always a joy to watch. We will know this weekend how we stand in relation to the championship, opinion is very much 50/50. Some are saying it’s Ireland’s, that the French are in tatters, others believe Les Bleus are ready to mount the mother and father of all challenges to claim the title, French passion will lead to French flair to growing confidence and suddenly there’s a rolling maul heading for the Irish try line. Ronan O’ Gara is wary of the French attack and I am inclined to agree with him. I agree absolutely with you on Brian O’ Driscoll, what a warrior\!!, I don’t know how this man has survived the game, from head spears to head wounds to broken, twisted legs and bones and the man just keeps on getting up and smiling, talk about a love of the game!, A real professional if ever there was one! He will be sorely missed after next weekend.
I came across your blog on a page called The Calculus Diaries, delighted to have found you, like yourself I am in total awe of all of what is going on around me in this place we call The Universe, I only know that I know next to nothing about this whole Creation but I always did love Science and Isaac Newton. Some years back I bought The Principia to try to understand why Newton had to devise Calculus in relation to celestial mechanics, sadly this was a bridge too far for my understanding but I will keep searching until I learn. I never learned calculus at school and only found out about this totally amazing application of maths a few years ago. With calculus I believe Nature opens up all her secrets about just how much Nature and mathematics are intertwined. I also believe that we are all here for a purpose and that in spite of what Richard Dawkins says, the must be a Prime Mover, there is too much mathematical attention to detail in this Creation for it to have happened out of the blue (or even Le Bleu!!) We live within nature that is governed like a giant clockwork mechanism down to the millisecond, the Sun sets and rises, the Moon pulls on the tides, just now , leaves are beginning to show on trees and daffodils are budding, we live in miraculous times and yet we must hone our attention to everything that is taking place about us to realise this, Mother Nature never sleeps!
Thank you for the interesting comments. With the rugby, all will be revealed this weekend! As far as calculus is concerned, yes one cannot do some of the mathematics necessary to describe many aspects of physics without using calculus. Maths is the language of nature, or at least the way we have found to describe it.
Hey, I read quite a number of your posts. They are really informative. I’m glad I found your blog. But I also read your posts on religion. You are a PhD in Astrophysics, something that occupies a lot of place in my heart too, it’s fascinating. So, what is your idea of GOD after knowing all possible things about the big-bang? How do you view this aspect? I am just passionately curious!
Thank you for the comment. I didn’t realise I had written any posts on religion, it’s one subject I’m reluctant to blog about. As an astrophysicist neither I nor my colleagues know all possible things about the Big Bang, and my own feeling is that there will always be unanswered questions, but that they may be questions of finer and finer detail. I’m glad you’re passionately curious, and religion or belief in a Creator should never be used as an excuse to not ask important questions or to seek answers using the scientific method.
Thank You 🙂
The Big-Bang theory has both a storied past and present and it is not what most people believe it to be (i.e., scientific fact similar to geologic time, etc.). Anyone interested in cosmology should read this new material (or at least try): http://sensibleuniverse.com/slides
I’ll take a look, but the big bang theory has a lot of supporting evidence.
Good point. “Evidence” is defined as “the available body of information indicating whether a belief or proposition is true or valid.” A distinction must be drawn between “information” and “facts”. Evidence may be illusory or contrived and that is one important theme of this document, which includes brief discussion of relevant ideas from Kuhn and Popper.
Your translation of “Hon” into English was beautiful. I’m only just beginning to learn the language, but I can sense you captured the spirit of that poem far better than the dictionary translations I’ve come across. Diolch yn fawr.
Diolch 🙂
Did you know that Queen’s Brian May also has a PhD in astrophysics?
Yes I did, and it’s from where I did my undergraduate degree (Imperial College London) 🙂
Found your blog under Astronomy section, loved it. 🙂
spacevash.com
Thanks for the very interesting and entertaining talk yesterday evening at the Museum of the Scientific Society Swakopmund. Do you mind if I link this blog on our website (http://scientificsocietyswakopmund.com/)?
Thank you, I’m glad that you enjoyed it.
Of course, I’m happy for you to link my blog on your website. I’d be honoured 🙂
“Football”: football or soccer?
“Football” is what most of the world calls soccer.
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Great site. Clear explanations. Your students are very fortunate.