Magazine issue 2755
WHY do distant galaxies seem to age at the same rate as those closer to us when big bang theory predicts that time should appear to slow down at greater distances from Earth? No one can yet answer this new question, but one controversial idea is that the galaxies' light is being bent by intervening black holes that formed shortly after the big bang.
Space has been expanding since the big bang, stretching light from distant objects to longer, redder wavelengths - a process called "red shift". The expansion means that distant events appear to occur more slowly than those nearby. For example, the interval between light pulses leaving a faraway object once per second should have lengthened by the time they reach Earth because space has expanded during their trip.
Is the big bang theory wrong? (Image: Lynette Cook/Science Photo Library)
Supernovae show this "time dilation" in the speed at which they fade - far-off explosions seem to dim more slowly than those nearby. But when Mike Hawkins of the Royal Observatory in Edinburgh, UK, looked at light from quasars he found no time dilation (Monthly Notices of the Royal Astronomical Society, in press).
All quasars are broadly similar, and their light is powered by matter heating up as it swirls into the giant black holes at the galaxies' cores. So one would expect that a brightness variation on the scale of, say, a month in the closer group would be stretched to two months in the more distant group. "To my amazement, the [light signatures] were exactly the same," he says. "There was no time dilation in the more distant objects."
So what's going on? Hawkins classes possible explanations as "wacky" or "not so wacky". The wacky ideas include the possibility that the universe is not expanding, or that quasars are not at the distances indicated by the red shifts of their light - an idea that has previously been discredited.
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Read more here/Leia mais aqui: New Scientist
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On time dilation in quasar light curvesM. R. S. Hawkins 1
1 Institute for Astronomy (IfA), University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ
Correspondence to E-mail: mrsh@roe.ac.uk
KEYWORDS
quasars: general • cosmology: observations
ABSTRACT
In this paper we set out to measure time dilation in quasar light curves. In order to detect the effects of time dilation, sets of light curves from two monitoring programmes are used to construct Fourier power spectra covering time-scales from 50 d to 28 yr. Data from high- and low-redshift samples are compared to look for the changes expected from time dilation. The main result of the paper is that quasar light curves do not show the effects of time dilation. Several explanations are discussed, including the possibility that time dilation effects are exactly offset by an increase in time-scale of variation associated with black hole growth, or that the variations are caused by microlensing in which case time dilation would not be expected.
Accepted 2010 February 23. Received 2010 February 19; in original form 2010 January 29
DIGITAL OBJECT IDENTIFIER (DOI)10.1111/j.1365-2966.2010.16581.x
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NOTA DESTE BLOGGER:
Quem sou eu para ensinar ciência ao Marcelo Gleiser, mas suas colunas na Folha de São Paulo deveriam abordar temas estritamente científicos como este aqui. Suas colunas tentam compatibilizar os dogmas sagrados da ciência e da fé.
O que esta pesquisa indica. Uma mudança paradigmática em astronomia? Em cosmologia? E em biologia evolutiva, não? Por que, se Darwin não fecha as contas epistêmicas no contexto de justificação teórica desde 1859? Ciência ou ideologia???
Quem sou eu para ensinar ciência ao Marcelo Gleiser, mas suas colunas na Folha de São Paulo deveriam abordar temas estritamente científicos como este aqui. Suas colunas tentam compatibilizar os dogmas sagrados da ciência e da fé.
O que esta pesquisa indica. Uma mudança paradigmática em astronomia? Em cosmologia? E em biologia evolutiva, não? Por que, se Darwin não fecha as contas epistêmicas no contexto de justificação teórica desde 1859? Ciência ou ideologia???
