In a paper posted on the arXiv preprint server, Christof Wetterich (above), a theoretical
physicist at the University of Heidelberg in Germany, has devised a different
cosmology in which the universe is not expanding but the mass of everything has
been increasing. Such an interpretation could help physicists to understand
problematic issues such as the so-called singularity present at the Big Bang,
he says.
Astronomers measure whether objects are moving away
from or towards Earth by analyzing the light that their atoms emit or absorb,
which comes in characteristic colors, or frequencies. When matter is moving
away from us, these frequencies appear shifted towards the red, or
lower-frequency, part of the spectrum, in the same way that we hear the pitch
of an ambulance siren drop as it speeds past.
In the 1920s, astronomers including Georges LemaƮtre
and Edwin Hubble found that most galaxies exhibit such a redshift — and that
the redshift was greater for more distant galaxies. From these observations,
they deduced that the Universe must be expanding.
The Paradox
But, as Wetterich points out, the characteristic
light emitted by atoms is also governed by the masses of the atoms' elementary
particles, and in particular of their electrons. If an atom were to grow in
mass, the photons it emits would become more energetic.
Because higher energies
correspond to higher frequencies, the emission and absorption frequencies would
move towards the blue part of the spectrum. Conversely, if the particles were
to become lighter, the frequencies would become red shifted.
Because the speed of light is finite, when we look
at distant galaxies we are looking backwards in time — seeing them as they
would have been when they emitted the light that we observe.
If all masses were
once lower, and had been constantly increasing, the colors of old galaxies
would look red shifted in comparison to current frequencies, and the amount of
redshift would be proportionate to their distances from Earth. Thus, the
redshift would make galaxies seem to be receding even if they were not.
Work through the maths in this alternative
interpretation of redshift, and all of cosmology looks very different. The
Universe still expands rapidly during a short-lived period known as inflation.
But prior to inflation, according to Wetterich, the Big Bang no longer contains
a 'singularity' where the density of the Universe would be infinite. Instead,
the Big Bang stretches out in the past over an essentially infinite period of
time. And the current cosmos could be static, or even beginning to contract.
So now, we could
implode… I guess?
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