The Singular Universe and the Reality of Time

Stephen Town invites you to challenge your views on the Universe and physics as we know it, in the latest blog from his Nightshelf.

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Unger, R., Smolin, L., The Singular Universe and Reality of Time, in the University Library at A13 UNG

Is time real? Can the past also be the future?
Image by Bonnyb. Reproduced from pixabay

This is an ambitious, controversial and probably difficult book for anyone who has not thought or read much about the nature of the Universe or taken a position on the debates about what the world we experience is made of and the laws that govern it (what the authors term ‘the foundational problems of basic science’). However it would be nice to think that any member of this University might feel inclined to at least give this work a try.

Unger and Smolin have been working for at least eight years on a new synthesis (in their words ‘a reinterpretation’) of twentieth-century cosmology and physics. This is accompanied by the recovery of the importance of the idea and methods of what used to be called ‘Natural Philosophy’. Smolin is a scientist reportedly considered tiresome and iconoclastic by his colleagues. Unger is a Harvard law Professor and politician. Both write their own piece in this book in their own style, and also reflect on their differences.

Is there a universe beyond our own?
Unger and Smolin argue the case for us being alone.

Their three main propositions run counter to current scientific views: that the Universe is singular; that time has reality; and that mathematics has only selective realism. Maybe you think these positions are common-sense and obvious? Or maybe you believe strongly in the current orthodoxy? Either way you want to read this book.

ScienceDirect

Academic Liaison Librarian for Chemistry, Computer Science, Electronics and Physics, Clare Ackerley, provides some tips on how to get the most out of this resource.

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ScienceDirect is a full-text database that provides access to over 2,500 journals and over 30,000 books. In addition to Physical Sciences, Life Sciences and Health Sciences, ScienceDirect has coverage of Social Sciences and Humanities, including History, Education and Linguistics and Language.

Here are some tips on using the ScienceDirect database:

1. Register online

Registering online, allows you to save your searches, set up alerts and view your search history. Simply follow the 'Sign in' option on the top right-hand side of the screen.

Tip: If you have already registered with Scopus, you can use the same login.

2. Select Advanced Search

Using the Advanced Search option will ensure you get relevant, rich results.

There are different search forms for different resources, including journals, books and images. You could use the image search form if you are specifically looking for photos, figures or tables for example.

3. Explore mobile device article

ScienceDirect recently launched their mobile device article which makes navigating and reading the full text on a small screen much easier.

The search bar is at the top of the screen while other options such as article navigation, exporting and PDF are at the bottom.

4. Manage your references

ScienceDirect is available to University of York users via the E-resources Guide, or you can explore other useful resources for your subject on your department’s Subject Guide. ScienceDirect can be used with EndNote Online to help you collect and manage your references - more information is available on our Reference Management site.

5. Ask for help if you need it!

There is a handy Quick Reference Guide to ScienceDirect and also some great online tutorials. And if all that isn’t enough, you can follow them on Twitter or keep up to date with the ScienceDirect Blog.

For more advice about using electronic resources and for general advice about Library resources for your department contact your Academic Liaison Librarian (you can find their contact details on the Subject Guide for your department).

How to cycle as fast as Bradley Wiggins...

A special Tour de France guest post by Dr Phil Lightfoot - Department of Physics

Unfortunately for my employers, the best ideas always seem to come to me en route to and from work, while cycling to the University on my mountain bike.

Temporarily disconnected from the web, my thoughts are forced inward and my imagination begins to wander. Despite the fact that the design has failed to significantly evolve in over 100 years, bicycles still represent the most convenient and efficient means of human powered transportation.

Photo: Bradley Wiggins, by Surrey County Council.
Reproduced under a Creative Commons licence.

But why has bicycle design appeared to stagnate while the technology associated with motorcycles has consistently developed? What is the limiting factor and what can be done to overcome it? The answer regrettably is hitting cyclists in the face daily.

The average speed of winners of the Tour de France in the last 10 years is 24.9 mph. My highest recorded average speed along 8 miles of quiet country roads between the Physics department and a very disgruntled hungry cat stands at 19.5 mph. At first glance it may therefore seem within the realms of possibility that I could dedicate every fibre to pushing the envelope and bridging this small speed differential.

Sadly physics has other ideas.

Setting aside the world of lycra for a moment, let us consider petrol-powered transport:

• A Bugatti Veyron sports car uses 987 horsepower (hp) to propel it to an impressive top speed of 267 mph;
• But a Ford Fiesta needs only 99 hp to reach roughly half that speed. 
• Perhaps the best evidence of basic physics at work was the top speed of 172 mph set by a 78 hp Moto Guzzi motorcycle in 1957 (it was almost 20 years before that speed was reached again in racing). 
• This feat was attributed not to the power of its engine but to the aerodynamics of its design. 

Isaac Newton is largely responsible for deciphering the associated physics. Basic Newtonian mechanics states that at top speed the net force propelling a vehicle forwards must equal the net force dragging it in the opposite direction. Therefore in order to increase top speed without any increase in supplied power, the forces of drag must be reduced.

So, to relate that back to bicycles: drag associated with cycling is made up of rolling resistance and aerodynamic drag. The force Frr due to rolling resistance is given by the relatively intimidating expression (below) in which Wf and Wr refer to the weight acting through the front and rear tyres and P is the pressure within them. The constants a, b and c depend on a number of factors such as the road surface, bearing friction, tyre construction, surface temperature and the ‘knobbliness’ of the tread pattern.

The only good news is that rolling resistance can be significantly reduced by decreasing the weight of the rider and bicycle, increasing the tyre pressures, and reducing the contact patch made between the tyres and the ground. Tour de France racing tyres for example are triple the pressure and a third the width of the tractor tyres fitted to my bicycle. The riders too are approximately half my weight.

Aerodynamic drag is a result of the viscosity of air, a boundary layer forming around the bicycle which affects pressure distribution and disrupts the smooth laminar flow. This disturbance creates an area of high pressure directly in front of the rider - reducing forward velocity.

Alexander Vinokourov.jpg - Wikimedia Commons.
Used under a Creative Commons licence.

Perhaps a little surprisingly however, the shape of the rear of the bicycle/rider combination has a greater effect on drag than the shape of the front because of the turbulence created as disturbed air falls into the partial vacuum created. As is equally true for aircraft wings, the optimum shape in order to reduce aerodynamic drag is widest at 20% of its length and then tapers by 10 degrees from there rearwards. This explains some of the weird and wonderful shapes of helmets and bikes you see in professional time trials (it doesn't explain the colours however).

    

The figures above demonstrate airflow around (a) the torso of an upright commuter, (b) an unprotected head, and (c) the aero-helmets commonly used by time trial racers. Any sharp variation in profile leads to the onset of turbulence, the air unable to follow the contours of the shape generating a partial vacuum which further upsets flow. 

The total aerodynamic drag force in newtons is given by the following expression for which v is the speed in m/s and A is the projected frontal area in m². The drag coefficient Cd  depends on the shape and surface smoothness of the object and the nature of the medium through which it travels. Cd  is 2.0 for a flat plate perpendicular to the air, 1.0 for a smooth ball, 0.3 for a sports car, 0.7 for a mountain bike and anything down to 0.2 for a race bike and professional rider.

VeloX3.jpg - Wikimedia Commons. Used under a Creative Commons licence.

Incidentally, it is always the case that a compromise must be reached between the drag coefficient and the projected frontal area, a streamlined flow necessitating a more bulbous shape. For example the current unassisted land speed record for a bicycle of 83 mph was set in 2013 by VeloX3, a recumbent design encased in a large aerodynamic faring.

This information provides us with a key insight. First however we must revisit Newton who determined the relationship between power P in watts, speed v in m/s and propulsive force Fdrive in newtons given below.

The current motor-paced record, in which a cyclist rides directly behind a powered vehicle shielding the rider from the effects of drag, stands at 167 mph. This indicates the dominance of aerodynamic drag. If we neglect rolling resistance and equate the forces of aerodynamic drag and propulsion we arrive at the following expression. Remember that if the propulsive and drag forces balance, there is no net force and so v will represent top speed.

The specific values aren't as interesting as the relationship between power and top speed which suggests that in order to double top speed, a rider must supply eight times the power. I can cycle at 20 mph and Wiggins and the other professionals can easily cycle at 25 mph; however that 5 mph difference between commuter and pro-racer corresponds to almost double the power output. Not even a grumpy cat is able to provide sufficient encouragement for me to span that divide!

Not the author's cat. Picture courtesy of www.catshaming.co.uk.

The Flying Saucer Review: tales of our journal collection

Last month was an unusual change of pace for me as I spent many afternoons mucking in with the big journal move out to our new external store in Nether Poppleton. I have yet to visit this voluminous space, but of course like everyone else I have been imagining that vault from Indiana Jones and the Raiders of the Lost Ark. For someone who normally sits in front of a computer screen all day it was great fun to get my hands dirty. In this case, quite literally as handling dusty back issues of journals is a rather grubby task!
One of the unexpected pleasures of the task has been having a perusal of the weird and wonderful journals which the library has to offer.

Flying Saucer Review

My favourite so far has been the Flying Saucer Review.

At first I was sure that the enticing name would turn out to be a bit of false advertising but no, this magazine is about UFOs and the possible existence of aliens. I could not help but wonder which department had sponsored the acquisition of these periodicals.

Was it Physics? After all the debate about life on other planets and the possible existence of a technologically superior species has become increasingly scientific, or at least pseudo-scientific in some cases. There seems to have been a whole spate of documentaries in recent years investigating with contemporary scientific understanding a range of previously far fetched notions. I have watched everything from a 'serious' investigation into the viability of the warp drive and other futuristic technology seen on Star Trek, to a proposed theory that aliens are really a highly evolved future variant of the human race which has discovered time travel and now travels back to our present time for a reason or reasons unknown. Personally, that last idea is a bit too Terminator for my liking.

Another department who could be interested is Sociology. Surely if there was intelligent life apart from on earth, the potential questions raised about how we view ourselves as a species would be numerous and contentious. Never mind the problems of a global society, what about an intergalactic one? Would we see a revival of etiquette books? Would racial divisions here on earth lessen as we felt drawn together by simply being human? How would world religions be affected? Oh, the questions are entertaining and  endless :-)

If the Flying Saucer Review has whetted your appetite for journal consumption, then let me point you in the direction of a few more of my favourites which cover a broad range of topics:

1. The Penguin Film Review - Number 3 from 1947 has beautiful black and white stills depicting 'Decor in Recent Russian Cinema' and 'Italian Films since the Liberation'. If you want to annoy your film buff friends by knowing what was written about iconic world cinema when it was actually released then this is the journal for you.

2.Corona: The Journal of His Majesty’s Colonial Service -I opened this volume purely by chance and was surprised to find it an entertaining time capsule from a bygone era. With serious Bond-esque undertones, volume 1 from 1947 gave me a selection of materials all relating to the colonies. The open letters were particularly intriguing including the titles: Experimental Power Surf Boat, Foetid Fragrance, Plea for the Camel and Fortune in a Tanganyika Swamp.

North Riding Pictorial Journal

3. North Riding Pictorial Journal (1858-58) -Stunning prints depicting 'Nest of the Mole Cricket' or a Crochet night cape'. Quaint, Victorian and very charming and even better, located firmly in Yorkshire.

Bad Attitude

4. Bad Attitude: The Radical Women’s Newspaper -who could fail to be intrigued by the article Sodomites and Man-Royals as found in the Autumn/Winter issue 8 1995?

Journals, like our books, are catalogued on YorSearch - and even those that have been moved to the external store can be requested and made available to you.

As a final note, when I was writing this blog I could not (much to my shame) remember which Indiana Jones movie had the scene with the huge storage facility in it and had to turn to Google to supply the answer. As I skimmed the list of results, I spotted the link to this article:
Raiders of the Lost Archives

Of course I had to have a look. In the article John Sutherland, an English professor, recalls his own pre-digital world of research which consisted more often than not of hopping on various modes of transport and hoping that the distant archive/library/collection he was heading to would have what he was looking for. Having completed my own MA slap bang in the middle of e-journals and Google books, I couldn't imagine a more different experience. The article struck a chord with something that I had experienced all through the journal moving process: that wondrous shiver of delight at finding something new. I must admit that I even spotted a few volumes I really wish I had known about when I was writing my dissertation. It made me think that while on-line catalogues, research aids and journal databases have revolutionised how we conduct research and indeed have opened up whole new vistas in information gathering, it is no harm to just go and browse. While you are there, spare a thought for researchers and enthusiasts who have gone before us, one dust-covered, grubby hand at a time.