In the latest issue:

Real Men Go to Tehran

Adam Shatz

What Trump doesn’t know about Iran

Patrick Cockburn

Kaiser Karl V

Thomas Penn

The Hostile Environment

Catherine Hall

Social Mobilities

Adam Swift

Short Cuts: So much for England

Tariq Ali

What the jihadis left behind

Nelly Lahoud

Ray Strachey

Francesca Wade

C.J. Sansom

Malcolm Gaskill

At the British Museum: ‘Troy: Myth and Reality’

James Davidson

Poem: ‘The Lion Tree’

Jamie McKendrick

SurrogacyTM

Jenny Turner

Boys in Motion

Nicholas Penny

Jia Tolentino

Lauren Oyler

Diary: What really happened in Yancheng?

Long Ling

Short Cuts: Harry Goes Rogue

Jonathan Parry

Cosmic InflationDavid Kaiser
Close

Terms and Conditions

These terms and conditions of use refer to the London Review of Books and the London Review Bookshop website (www.lrb.co.uk — hereafter ‘LRB Website’). These terms and conditions apply to all users of the LRB Website ("you"), including individual subscribers to the print edition of the LRB who wish to take advantage of our free 'subscriber only' access to archived material ("individual users") and users who are authorised to access the LRB Website by subscribing institutions ("institutional users").

Each time you use the LRB Website you signify your acceptance of these terms and conditions. If you do not agree, or are not comfortable with any part of this document, your only remedy is not to use the LRB Website.


  1. By registering for access to the LRB Website and/or entering the LRB Website by whatever route of access, you agree to be bound by the terms and conditions currently prevailing.
  2. The London Review of Books ("LRB") reserves the right to change these terms and conditions at any time and you should check for any alterations regularly. Continued usage of the LRB Website subsequent to a change in the terms and conditions constitutes acceptance of the current terms and conditions.
  3. The terms and conditions of any subscription agreements which educational and other institutions have entered into with the LRB apply in addition to these terms and conditions.
  4. You undertake to indemnify the LRB fully for all losses damages and costs incurred as a result of your breaching these terms and conditions.
  5. The information you supply on registration to the LRB Website shall be accurate and complete. You will notify the LRB promptly of any changes of relevant details by emailing the registrar. You will not assist a non-registered person to gain access to the LRB Website by supplying them with your password. In the event that the LRB considers that you have breached the requirements governing registration, that you are in breach of these terms and conditions or that your or your institution's subscription to the LRB lapses, your registration to the LRB Website will be terminated.
  6. Each individual subscriber to the LRB (whether a person or organisation) is entitled to the registration of one person to use the 'subscriber only' content on the web site. This user is an 'individual user'.
  7. The London Review of Books operates a ‘no questions asked’ cancellation policy in accordance with UK legislation. Please contact us to cancel your subscription and receive a full refund for the cost of all unposted issues.
  8. Use of the 'subscriber only' content on the LRB Website is strictly for the personal use of each individual user who may read the content on the screen, download, store or print single copies for their own personal private non-commercial use only, and is not to be made available to or used by any other person for any purpose.
  9. Each institution which subscribes to the LRB is entitled to grant access to persons to register on and use the 'subscriber only' content on the web site under the terms and conditions of its subscription agreement with the LRB. These users are 'institutional users'.
  10. Each institutional user of the LRB may access and search the LRB database and view its entire contents, and may also reproduce insubstantial extracts from individual articles or other works in the database to which their institution's subscription provides access, including in academic assignments and theses, online and/or in print. All quotations must be credited to the author and the LRB. Institutional users are not permitted to reproduce any entire article or other work, or to make any commercial use of any LRB material (including sale, licensing or publication) without the LRB's prior written permission. Institutions may notify institutional users of any additional or different conditions of use which they have agreed with the LRB.
  11. Users may use any one computer to access the LRB web site 'subscriber only' content at any time, so long as that connection does not allow any other computer, networked or otherwise connected, to access 'subscriber only' content.
  12. The LRB Website and its contents are protected by copyright and other intellectual property rights. You acknowledge that all intellectual property rights including copyright in the LRB Website and its contents belong to or have been licensed to the LRB or are otherwise used by the LRB as permitted by applicable law.
  13. All intellectual property rights in articles, reviews and essays originally published in the print edition of the LRB and subsequently included on the LRB Website belong to or have been licensed to the LRB. This material is made available to you for use as set out in paragraph 8 (if you are an individual user) or paragraph 10 (if you are an institutional user) only. Save for such permitted use, you may not download, store, disseminate, republish, post, reproduce, translate or adapt such material in whole or in part in any form without the prior written permission of the LRB. To obtain such permission and the terms and conditions applying, contact the Rights and Permissions department.
  14. All intellectual property rights in images on the LRB Website are owned by the LRB except where another copyright holder is specifically attributed or credited. Save for such material taken for permitted use set out above, you may not download, store, disseminate, republish, post, reproduce, translate or adapt LRB’s images in whole or in part in any form without the prior written permission of the LRB. To obtain such permission and the terms and conditions applying, contact the Rights and Permissions department. Where another copyright holder is specifically attributed or credited you may not download, store, disseminate, republish, reproduce or translate such images in whole or in part in any form without the prior written permission of the copyright holder. The LRB will not undertake to supply contact details of any attributed or credited copyright holder.
  15. The LRB Website is provided on an 'as is' basis and the LRB gives no warranty that the LRB Website will be accessible by any particular browser, operating system or device.
  16. The LRB makes no express or implied representation and gives no warranty of any kind in relation to any content available on the LRB Website including as to the accuracy or reliability of any information either in its articles, essays and reviews or in the letters printed in its letter page or material supplied by third parties. The LRB excludes to the fullest extent permitted by law all liability of any kind (including liability for any losses, damages or costs) arising from the publication of any materials on the LRB Website or incurred as a consequence of using or relying on such materials.
  17. The LRB excludes to the fullest extent permitted by law all liability of any kind (including liability for any losses, damages or costs) for any legal or other consequences (including infringement of third party rights) of any links made to the LRB Website.
  18. The LRB is not responsible for the content of any material you encounter after leaving the LRB Website site via a link in it or otherwise. The LRB gives no warranty as to the accuracy or reliability of any such material and to the fullest extent permitted by law excludes all liability that may arise in respect of or as a consequence of using or relying on such material.
  19. This site may be used only for lawful purposes and in a manner which does not infringe the rights of, or restrict the use and enjoyment of the site by, any third party. In the event of a chat room, message board, forum and/or news group being set up on the LRB Website, the LRB will not undertake to monitor any material supplied and will give no warranty as to its accuracy, reliability, originality or decency. By posting any material you agree that you are solely responsible for ensuring that it is accurate and not obscene, defamatory, plagiarised or in breach of copyright, confidentiality or any other right of any person, and you undertake to indemnify the LRB against all claims, losses, damages and costs incurred in consequence of your posting of such material. The LRB will reserve the right to remove any such material posted at any time and without notice or explanation. The LRB will reserve the right to disclose the provenance of such material, republish it in any form it deems fit or edit or censor it. The LRB will reserve the right to terminate the registration of any person it considers to abuse access to any chat room, message board, forum or news group provided by the LRB.
  20. Any e-mail services supplied via the LRB Website are subject to these terms and conditions.
  21. You will not knowingly transmit any virus, malware, trojan or other harmful matter to the LRB Website. The LRB gives no warranty that the LRB Website is free from contaminating matter, viruses or other malicious software and to the fullest extent permitted by law disclaims all liability of any kind including liability for any damages, losses or costs resulting from damage to your computer or other property arising from access to the LRB Website, use of it or downloading material from it.
  22. The LRB does not warrant that the use of the LRB Website will be uninterrupted, and disclaims all liability to the fullest extent permitted by law for any damages, losses or costs incurred as a result of access to the LRB Website being interrupted, modified or discontinued.
  23. The LRB Website contains advertisements and promotional links to websites and other resources operated by third parties. While we would never knowingly link to a site which we believed to be trading in bad faith, the LRB makes no express or implied representations or warranties of any kind in respect of any third party websites or resources or their contents, and we take no responsibility for the content, privacy practices, goods or services offered by these websites and resources. The LRB excludes to the fullest extent permitted by law all liability for any damages or losses arising from access to such websites and resources. Any transaction effected with such a third party contacted via the LRB Website are subject to the terms and conditions imposed by the third party involved and the LRB accepts no responsibility or liability resulting from such transactions.
  24. The LRB disclaims liability to the fullest extent permitted by law for any damages, losses or costs incurred for unauthorised access or alterations of transmissions or data by third parties as consequence of visit to the LRB Website.
  25. While 'subscriber only' content on the LRB Website is currently provided free to subscribers to the print edition of the LRB, the LRB reserves the right to impose a charge for access to some or all areas of the LRB Website without notice.
  26. These terms and conditions are governed by and will be interpreted in accordance with English law and any disputes relating to these terms and conditions will be subject to the non-exclusive jurisdiction of the courts of England and Wales.
  27. The various provisions of these terms and conditions are severable and if any provision is held to be invalid or unenforceable by any court of competent jurisdiction then such invalidity or unenforceability shall not affect the remaining provisions.
  28. If these terms and conditions are not accepted in full, use of the LRB Website must be terminated immediately.
Close
Time Reborn: From the Crisis in Physics to the Future of the Universe 
by Lee Smolin.
Allen Lane, 319 pp., £20, April 2013, 978 1 84614 299 4
Show More
Show More

The Austrian polymath Ernst Mach exhorted his fellow physicists in the early 1880s to recognise that all was not well with their discipline. Two hundred years earlier, Isaac Newton had bequeathed to them a remarkable system of laws which made it possible for them to describe – and predict – the motion of everything from an apple falling from a tree near Woolsthorpe to the orbit of the Moon around the Earth. When Mach was still a child, it had been concluded on the strength of Newton’s laws that there must be an as yet unseen planet in the solar system, its presence deduced from subtle wobbles in the orbit of Uranus. In 1846, the discovery of Neptune was celebrated across Europe as one more victory for Newtonian physics.

But Mach wasn’t satisfied. Portraits show a brooding man peering through narrow spectacles and sporting the kind of beard that had become common among intellectuals of the late Habsburg era. He had done well-respected research in optics, and his studies of projectiles that move faster than the speed of sound – the resulting shock wave producing a characteristic ‘sonic boom’ – gave us the nomenclature of ‘Mach numbers’ (Mach 1, the speed of sound, was exceeded by test pilots in 1947; Mach 2, twice the speed of sound, in 1953). He also studied physiology and the psychology of perception. He could have had a professorship in surgery, but instead took chairs in mathematics and experimental physics. His final academic appointment was in the history and philosophy of science, a position he earned as a result of his persistent, withering critiques of Newton. He was as impressed as anyone with the practical applications of Newton’s laws. What troubled him was the array of assumptions that undergirded the enterprise. ‘The present volume is not a treatise on the application of the principles of mechanics,’ he wrote in the opening pages of The Science of Mechanics (1883). ‘Its aim is to clear up ideas, expose the real significance of the matter, and get rid of metaphysical obscurities.’ That last charge – ‘metaphysical obscurities’ – was meant to wound.

Mach was offended principally by Newton’s notions of absolute space and time. Over and over in The Science of Mechanics, he chides Newton for losing his way, cowering ‘under the influence of medieval philosophy’, growing ‘unfaithful to his resolve to investigate only actual facts’. For how could any reliable information ever be gleaned about such abstractions as ‘absolute space’? All we are in a position to investigate, he insisted, are relations between observable objects, such as the relative motion of real bodies. Yet Newton had built his entire system on an imagined platform of infinite, unbending, everlasting space and time, bolstered only by hand-waving about ‘the Sensorium of God’.

Mach countered that a proper science must be built on objects of ‘positive experience’: those which, at least in principle, could make some impact on an investigator’s senses. If some purported scientific object could not possibly affect the touch, taste, smell, hearing or sight of a diligent researcher, then better to cast it aside. Scientists shouldn’t allow such vacuous, metaphysical baggage to get in the way of progress. Accordingly, Mach refused to believe that atoms were real, despite the accumulation of indirect evidence, right up until he died in 1916.

We don’t hear much about the Sensorium of God in debates among today’s leading physicists and cosmologists, but there’s plenty that Mach would think just as silly. Physics journals these days are filled with speculation about an infinite plurality of universes, each governed by its own set of physical laws, all bubbling away in some larger multiverse. More metaphysical obscurities, Mach would grumble. But the speculation isn’t idle. Over the past 15 years, new ideas and new data have brought the notion of the multiverse roaring back to physicists’ attention.*

One of the catalysts was the surprising discovery in the late 1990s that our observable universe isn’t just expanding, but that its rate of expansion is increasing. The acceleration seems to be driven by a mysterious quasi-substance known as ‘dark energy’, which fills every nook and cranny of the universe. Physicists had previously thought that if they could find some large void in space – some region in which there was no matter whizzing about, no stars or planets distending the fabric of space-time – then such a void would have no energy at all. The existence of ‘dark energy’ suggests, on the contrary, that even such a vast emptiness carries some small amount of energy all its own. It is as if every time you stepped off the bathroom scales, the needle failed to settle all the way back to zero. When plugged into Einstein’s equations of general relativity, which quantify how space-time responds to the distribution of matter and energy, such residual energy behaves like a repulsive force. Space literally stretches itself out, faster and faster over time. The effects of that accelerated expansion can be measured, but the cause remains unknown. Physicists’ first thought was that dark energy arose as some quantum mechanical effect, perhaps related to the unavoidable jiggling of matter as governed by Heisenberg’s uncertainty principle. But when they tried to calculate the amount of dark energy one should therefore expect to find in our universe, their calculations foundered. The numbers were off by factors of the order 10120: a 1 followed by 120 zeros. That’s a whopping accounting error.

Whatever its origin, dark energy and the speeded-up stretching of space today resemble a process known as ‘cosmic inflation’ that many physicists believe occurred very early in the history of our universe. According to this, in just a cosmic blink, a mere billion-billion-billion-billionth of a second after the Big Bang, our observable universe stretched from the size of a single atom to the size of a galaxy. Our universe has continued to expand, albeit at a more stately pace, ever since. The theory has been tremendously successful in predicting many features of our observable universe, from its basic geometry, to the distribution of matter in superclusters of galaxies, to the most subtle wrinkles in space-time captured in the ‘cosmic microwave background radiation’, a remnant glow from the Big Bang. Quantitative predictions from inflation match the latest astronomical measurements to within a fraction of 1 per cent.

Yet most models of inflation also suggest a surprising corollary: once inflation begins, it never ends. At any given location in space, you might expect the rip-roaring acceleration to cease as the curious quantum state that drives inflation decays. Yet the rate at which space doubles in size during inflation is faster than the rate at which the quantum driving-force decays at any particular location. During the time it took for our own little patch of space to decay out of the inflating state, nearby regions would have ballooned exponentially larger, and so on, ad infinitum. If these inflationary models are taken at face value, then an infinite volume of space should exist beyond what we can detect.

Dark energy and inflation suggest that space can stretch exponentially quickly: the vast cosmic neighbourhood that we can see might be a preposterously small sample of everything that’s out there. What’s more, according to some theoretical physicists, whatever lies beyond our range of detection might bear little resemblance to the mundane patch of space-time we call home. They draw their inspiration from string theory, an esoteric effort to align the two great pillars of modern physics: relativity and quantum theory. Until recently physicists were content to think of matter as tiny, shrunken billiard balls: electrons and quarks were assumed to be mere pin-pricks with no shape or extension at all. String theorists propose that matter consists not of point-like objects, but of strings: tiny, stretched-out filaments that can vibrate at particular frequencies like plucked guitar strings. The size of the strings must be immeasurably small, about a hundred billion billion times smaller than the nucleus of a hydrogen atom. Yet by taking strings rather than particles to be the basic ingredients of matter, string theorists have demonstrated that the equations of relativity governing space-time, on the one hand, and those governing quantum mechanical forces between bits of matter, on the other, might be limiting cases of a single set of overarching laws. The contrivance only works if string theorists impose all manner of strict symmetries on their equations: for every string-like wiggle in their theory (a vibration that would manifest as one type of particle) there must be a specific type of waggle (corresponding to a companion species of particle), and vice versa.

Over the past decade, both supporters and detractors of string theory have come to agree that this teetering, highly symmetric mathematical structure admits an unfathomable number of solutions. In fact, physicists now believe that the equations governing string theory admit about 10500 distinct solutions, any one of which (or none) might describe our physical universe. According to proponents of string theory, every physical constant that we know of, from the masses of elementary particles to the strengths of nuclear forces to the magnitude of dark energy, should depend on which of the 10500 distinct states was instantiated in our universe. Yet so far no one has found a way to predict which among these possibilities is most likely to occur.

Some enterprising theorists have tried to turn this massive bug into an asset. This is where the idea of the multiverse comes back into view. Combining the embarrassing richness of stringy possibilities with the idea of cosmic inflation (all in the light of the stubborn empirical fact that our own universe seems to contain some small amount of dark energy), they have suggested that every single one of the 10500 string states describes a real universe. And, given the eternally expanding, infinite volume of space suggested by inflation, they further suggest that each of these 10500 varieties of universe exists in an infinite number of copies. They’re all real, according to this viewpoint, and they’re all out there – and, most likely, they’re all completely undetectable by us. According to this line of thinking, the physical constants that we measure in our universe have the values they have not because they are required by the laws of physics, but because these are the values that produce a universe suitable for intelligent life. We wouldn’t have evolved in most of those other universes, so we wouldn’t be around to observe universes with very different characteristics.

Lee Smolin has picked up Mach’s mantle and begun to criticise the metaphysical obscurities he detects in the latest multiverse theories. Too much of today’s physics and cosmology, he argues, remains yoked to a Newtonian framework: Newton’s notions of absolute space and time might be gone, but the basic approach remains the same. In an effort to understand large and complicated systems (like the universe), physicists focus intensely on parts of it, then make tacit assumptions about the way the behaviour of the parts translates into that of the whole. This way of doing things has worked wonders since Newton, and over the past century alone, it is in essence how scientists have learned about atoms and molecules; quarks and Higgs bosons; planets, stars and galactic clusters. But Smolin argues that the game is up when it comes to tackling the universe itself.

The main problem with the Newtonian synecdoche, as Smolin sees it, is the mental leap required of us when isolating the part from the whole. It means ignoring all the many ways in which each part is embedded within the universe – all its myriad relationships and interactions with neighbouring parts. By practising this mental leap for centuries, Smolin believes, physicists have become accustomed to doing their calculations as if various cleaved-off parts could be treated as indistinguishable cogs within a cosmic machine. But Smolin insists that the cogs aren’t in fact identical: each is enmeshed in a slightly different set of relationships with the rest of the universe. Hence there can be no genuine sub-units; the parts are only approximately interchangeable, not fundamentally so.

If no two parts are genuinely indistinguishable, Smolin continues, then no purported symmetry in nature can be exact or fundamental. This is no small move. String theorists aren’t the only ones to have placed mathematical symmetries at the heart of their schemes. Challenging the centrality of symmetry means challenging the motivation that drove particle physicists on a fifty-year search for the Higgs boson, a once hypothetical particle whose existence physicists inferred entirely because of the strict symmetries that seem to govern nuclear forces. Demoting symmetry, as Smolin suggests physicists must do, also means discarding the assumption that every electron in the universe is fundamentally indistinguishable from every other electron. Yet that core assumption serves as the basis of physicists’ calculations of very specific properties of the electron – calculations that match experimental measurements to better than one part in ten trillion.

The most important symmetry threatened by Smolin’s new framework is the one Einstein helped establish between space and time. Citing relativity, most physicists argue that space and time are mere projections of a malleable space-time, with no particular significance beyond an individual’s frame of reference. Not so, counters Smolin: time is special. For a start, we all experience time differently from the way we experience space. Time only ever seems to move in one direction, but we think nothing of jogging back and forth in space. And we only perceive a single dimension of time. There seems to be no shortcut to jump from then to now, no way to do in time what my friends and I routinely used to do in space, cutting through our neighbour’s garden to shorten the walk to school.

If physicists returned time to a special category of its own, Smolin reasons, then physical laws would no longer stand outside of time; they would change and evolve just like the matter they purport to describe. And if that were so, then physicists could avoid some of today’s outlandish cosmological quandaries. The impulse to apply seemingly timeless laws – laws honed by close study of parts of the cosmos but not the whole – would be checked. No more need to posit an infinite plurality of other worlds, all of them forever choked off from our own. By treating time as fundamentally different from space, Smolin argues, physicists can get back to the business of trying to fathom our own universe without getting tripped up by phantasms of uncountable others.

Smolin has written some technical papers that attempt to shore up a new kind of physics in which time is real, rather than a mere shadow of some underlying space-time. But the work has not yet attracted many followers. So far, his critical project – trying to ferret out hidden assumptions in today’s standard models of physics and cosmology – has advanced further than any hoped-for replacement. The legacy of such a project remains difficult to predict. I suspect that few physicists will commit an about-face on reading Time Reborn, just as few physicists dropped what they were doing when Mach’s learned volumes appeared. But then again, it was reading Mach’s Science of Mechanics, a generation after it was published, that fired the imagination of a young Albert Einstein.

Send Letters To:

The Editor
London Review of Books,
28 Little Russell Street
London, WC1A 2HN

letters@lrb.co.uk

Please include name, address, and a telephone number.

Read anywhere with the London Review of Books app, available now from the App Store for Apple devices, Google Play for Android devices and Amazon for your Kindle Fire.

Sign up to our newsletter

For highlights from the latest issue, our archive and the blog, as well as news, events and exclusive promotions.