From the Sydney Morning Herald (here):
Melbourne researchers rewrite Big Bang theory
Melbourne researchers believe they may be on the brink of rewriting the history of the universe.
A paper being published in a US physics journal suggests it may be possible to view “cracks” in the universe that would support the theory of quantum graphity – considered to be the holy grail of physics.
The team of researchers from the University of Melbourne and RMIT say that, instead of thinking of the start of the universe as being a big bang, we should imagine it as a cooling of water into ice.
… Their research rests on a school of thought that has emerged recently to suggest space is made of indivisible building blocks, such as atoms, that can be thought of as similar to pixels that make up images on a computer screen.
Mr Quach said the standing model for the origins of the universe, the big bang, needed to be rewritten. He hoped experimentalists would be able to find evidence to support the theory put forward by the Melbourne team of researchers, that would replace it. “The biggest problem with the big bang model is the bang itself,” Mr Quach said. …
Mr Quach and his fellow researchers theorise that if quantum graphity “cracks” do exist, they will bend or reflect light, which, if observed through a telescope would support their predictions.
“If they prove my predictions that’s really good evidence for the condensed matter model of quantum graphity in which case you can throw out all the other attempts.”
Here’s a few pointers for the layman trying to decipher this article.
- Note how the claim of the title changes. “They’ve rewritten the big bang theory” becomes “they believe they’re about to rewrite the big bang theory” becomes “it may be possible to observe the consequences of a theory that might provide a model for the big bang”.
- The name “quantum graphity” is a pun on the terms quantum gravity and graph theory [edit: 1/9/2012]. Quantum gravity is the “holy grail” of physics (to some). Quantum graphity is not. The journalist evidently didn’t get the pun.
- Note that the article quotes Mr Quach. Not Dr or Professor. I love grad students, but claims that they are about to rewrite everything we know about the fundamental laws of nature and the entire history of the universe should be taken with a grain of salt.
- The paper that the article refers to contains no cosmology. It doesn’t claim to. None of Mr Quach’s papers do. What the paper shows is that, if spacetime consists of these building blocks, and the blocks get put together imperfectly, then light will scatter of the imperfection. The paper concludes: “they produce intriguing scattering, double imaging, and gravitational lensing-like eﬀects. Importantly this serves as a framework in which observable consequences of the QG model may allow it to be tested.”
- It is difficult to express just how astronomically huge the “if” is in the sentence “if observed through a telescope”. What observational signature should we be looking for? There are an awful lot of things in the universe that bend and deflect light. How would we distinguish between the observation of a graphity imperfection and other gravitational lenses? What unique predictions does the model provide? How many imperfections should we expect in the universe? What astronomical targets should we aim at?
- This idea isn’t new. The further we look in the universe, the more likely we are to see something funky along the way, so distant quasars have been used to test theories about interesting spacetime phenomena. So far: nothing. No evidence for quantum foam. No evidence for cosmic strings. No topological defects. Why would graphity defects be any different?
Even if the theory were true, and even if it did provide a model of “the bang itself” (none is referenced in the paper), this would not be “rewriting the big bang theory”. Not even close. The big bang theory is not just the statement that the universe started with an explosion (of sorts). The theory successfully accounts for a wide range of observations about the universe. Fossil evidence stretches back to nucleosynthesis when the universe was just minutes old, the cosmic microwave background (300,000 years), through observations of large scale structure and baryon acoustic oscillations and, the original evidence, the redshift of galaxies.
Cosmology is pure extrapolation, and while its success rightfully inspires further speculation, we should remember Martin Rees’ sage advice: “Despite the importance and fascination of the ultra-early universe, it would be imprudent to venture any bets on what happened [before the first second]. The empirical basis for these initial phases of cosmic history is far more tenuous than the quantitative ‘fossil evidence’ (from the light elements and background radiation) for the eras after one second.”
It is almost certain that no quantum gravity theory will rewrite the history of the universe after the first fraction of a second. The physics that governs the universe at that time and after is well-understood and well-tested, and the predictions well-confirmed. The most it will provide is a prediction for what happened in the first 10-42 th of a second (the Planck time). Cosmology textbooks will not be rewritten from scratch. They will have a new section, replacing the sentence “a prediction for what happened before the Planck time awaits a development of a theory of quantum gravity” with “here’s what quantum gravity predicts for the Planck era and here’s how the universe transitions into the classical big bang”. Of course there are still mysteries - it’s the whole universe we’re trying to understand. But theories aren’t elected as paradigms at random. A new theory must run the gauntlet of observational tests, not just tack a new bit on the front of the old theory.
This is exactly the science journalism we don’t need. I can’t say it any better than Ben Goldacre:
[In the media]… science is portrayed as groundless, incomprehensible, didactic truth statements from scientists, who themselves are socially powerful, arbitrary, unelected authority figures. They are detached from reality; they do work that is either wacky or dangerous, but either way, everything in science is tenuous, contradictory, probably going to change soon and, most ridiculously, ‘hard to understand’. Having created this parody, the commentariat then attack it, as if they were genuinely critiquing what science is all about.
We need journalists with the talent to take what scientists really do and think of a better headline than “Scientists make incremental progress in testing a theory”, “Scientists discover something somewhat unexpected” or “Scientists think of an interesting new theory and make small step towards developing of a way of testing to see if they’re right”. Headlines along the lines of “Scientists totally overturn everything we know about everything”, used too often, simply become background noise, above which the real progress of science struggles to be heard.