Atomism: Ancient & Modern

"Matter is constituted of particles, separated by comparatively large distances; it is embedded in empty space. This notion goes back to Leucippus and Democritus, who lived in Abdera in the fifth century B.C. This conception of particles and empty space is retained today ... and not only that, there is complete historical continuity." -- Erwin Schrödinger, physicist, Science and Humanism, 1951

"Is the ancient atomic theory, which is attached to the names of Leucippus and Democritus (born around 460 B.C.), the true forerunner of the modern one? This question has often been asked and very different opinions about it are on record. Gomperz, Cournot, Bertrand Russell, J. Burnet say: Yes." -- Erwin Schrödinger, physicist, Nature and the Greeks, 1954

"The difference between the two men, Democritus and Epicurus, was that Democritus was still modestly aware that he knew nothing, while Epicurus was very sure that he knew very little short of everything." -- Erwin Schrödinger, physicist, Nature and the Greeks, 1954

"... after Democritus the colours of physics were flown by philosophers who had no real interest in science ...." -- Erwin Schrödinger, physicist, Nature and the Greeks, 1954

"The question as to the origin of ancient atomism and to its connexion with modern theory is of much more than purely historical interest." -- Erwin Schrödinger, physicist, Nature and the Greeks, 1954

"We are facing here one of the most fascinating cases in the history of ideas. The astonishing point is this. From the lives and writings of Gassendi and Descartes, who introduced atomism into modern science, we know as an actual historical fact that, in doing so, they were fully aware of taking up the theory of the ancient philosophers whose scripts they had diligently studied. Furthermore, and more importantly, all the basic features of the ancient theory have survived in the modern one up to this day, greatly enhanced and widely elaborated but unchanged....." -- Erwin Schrödinger, physicist, Nature and the Greeks, 1954

"The connexions between Democritus and Newton are evident; and it would be absurd to deny the link between ancient and modern atomism; conceptually, there are narrow ties; historically, an unbroken (if curiously circuitous) line reaches from Leucippus to Rutherford." -- Jonathan Barnes, philosopher, The Presocratic Philosophers, 1982

"The revival of Democritus was what gave a thinker like Gassendi (who, unlike Galileo or Descartes, was no scientific inventor) such an important place in the theoretical grounding of modern science." -- José G. Merquior, philosopher, Foucault, 1987

"Concerning Schrödinger's question: is Democritus or Planck the founder of quantum theory?" -- Hans-Jürgen Treder, physicist, October 1987

"Democritus' atomism in principle is built only on quantities, namely the number and size of the atoms and their velocities. Here Democritus was far ahead of his time in that he took, preceding Galileo in assuming something like a law of inertia, each atom's velocity to be constant, unless a collision with another atom prevents it's free motion. For Democritus, the cosmos is a world of quantities uniquely given which continue their motion according to their own inertia until they are perturbed by other particles of the same nature." -- Hans-Jürgen Treder, physicist, October 1987

"Democritus's notion is compatible with our present belief." -- Leon M. Lederman, physicist, The God Particle, 2006

"... Democritus, held that matter was inherently grainy and that everything was made up of large numbers of various different kinds of atoms. (The word atom means 'indivisible' in Greek.) We now know that this is true -- at least in our environment, and in the present state of our universe." -- Stephen W. Hawking, mathematician, A Briefer History of Time, 2008

Doubts Linger Over Godless Multiverse

Above: proof there is a God.

"I believe that the more thoroughly science is studied the further does it take us from anything comparable to atheism." -- Lord Kelvin, physicist, March 1887

"Is there anything so absurd as to believe that a number of atoms by falling together of their own accord could make a crystal, a sprig moss, a microbe, and a living animal?" -- Lord Kelvin, physicist, 1903

Katy McAlpine: M-theory: Doubts linger over godless multiverse.

STEPHEN HAWKING'S new book The Grand Design sparked a furore over whether physics can be used to disprove the existence of God. But few have noted that the idea at the core of the book, M-theory, is the subject of an ongoing scientific debate – specifically over the very aspect of the theory that might scrap the need for a divine creator.

That the laws of nature in our universe are finely tuned for life seems miraculous, leading some to invoke divine involvement. But if there is a multiverse out there – a multitude of universes, each with its own laws of physics – then the conditions we observe may not be unique.

Hawking suggests that M-theory, the leading interpretation of string theory, calls for a multiverse. Others are divided over the strength of this link. "My own opinion is that we don't understand the theory well enough to be able to say whether there is one single universe or a multitude of universes," says M-theorist Michael Duff of Imperial College London.

String theory's grand claim was that it would be able to unite quantum mechanics with general relativity. Until the mid-1990s, however, five different versions of it, each featuring 10 spatial dimensions, were vying with each other, along with a sixth model known as 11-dimensional super-membrane theory. M-theory stitched these six theories together into one overarching theory. But while these six areas are fairly well fleshed out in M-theory, other parts of the theory are threadbare.

One major gap is how and where the seven extra spatial dimensions, beyond the three we experience, are hidden. "The conventional view is that the extra dimensions are very small," Duff says. Alternatively, our universe could exist within a "bulk" that contains the extra spatial dimensions.

A multiverse is compatible with both pictures, so some versions of M-theory are constructed to include a multiverse. However, some theorists argue that being compatible with M-theory does not make a multiverse essential. Duff adds that with our current patchy understanding of M-theory, the multiverse seems plausible enough, but it might not work if we could see the bigger picture. Even then, assuming multiple universes remain mathematically possible, there would still be no proof that they are actually present.

For now, it is hard enough to test string theory, let alone M-theory. Two weeks ago, Duff and his colleagues made some progress by using string theory to make predictions about the behaviour of entangled quantum bits (Physical Review Letters, DOI: 10.1103/PhysRevLett.105.100507). This demonstrates that aspects of string theory can be tested in the laboratory, but won't reveal if it is "the right theory to describe all the elementary particles, the big bang – the 'grand design' as Stephen describes it", says Duff.

"It's dangerous to pin your beliefs on any theory of physics," Duff adds, "because it might turn out to be wrong. But if Stephen wants to stick his neck out, I wish him good luck."

Hawking: Mankind Must Colonize Space or Face Extinction

News: Mankind must colonise space or face extinction, academic Stephen Hawking has warned.

MANKIND must look to colonize outer space within the next century or it will become extinct, renowned British astrophysicist Stephen Hawking warned the Big Think website yesterday.