According
to the Big Bang “sub-theory” of cosmic inflation, the universe rapidly
“stretched” in size during its initial expansion phase, and by that we mean the
expansion was “faster than light”. We therefore say the inflation mode is entirely in the realm
of 'false vacuum' in which a large and negative valued cosmological constant is
assumed. In the context of Einstein's theory of general relativity, the 'false
vacuum' may be thought of alternatively as contributing a cosmological constant
about 10-100 times larger than it can possibly be today. It is this peculiarity
which generates a corresponding 'repulsive' force, causing the universe to
inflate on an exponential scale.
Note that this sort of thing (implying velocities of expansion > c) isn't
particularly novel. In fact, a number of cosmological models posit that proper
distances, i.e. between clusters of galaxies, may increase faster than the
speed of light. To fix ideas here, if
the initial size of the universe was 1 fm (Fermi = 10 -15 m or about
the size of a proton) then the inflating cosmos would have attained a scale of
about eight times the Earth-Sun distance (8 astronomical units) after 90
doubling times, with periods ranging from 10 -43 secs to 10 -36
secs.
This
phenomenon also explains why the
universe is basically uniform. The
problem is that before the BICEP2 (Background Imaging of Cosmic Extragalactic
Polarization) results were announced March 17 it was all speculation. The paper
on which the results were based has since been submitted to the Journal Nature and should be available soon.
To
grasp how significant this is consider this:
No telescope exists – even the Hubble – that can see anything older than
the oldest light which comes from 380,000 years after the Bjg Bang or long
after inflation ended.
The
BICEP2 team discovered that this light, called the CMB or “cosmic microwave
background” has a major defect or “scar”
from the cosmos’ early violent expansion. This is by way of polarization or a
particular orientation of the light waves emanating from the CMB. Astrophysicists had predicted that inflation
generated gravitational waves that warped space time through which any photons
traveled. If in fact this was so, then the CMB ought to have a characteristic
“swirling” polarization known as a B-mode. Light is polarized when its electromagnetic
waves are preferentially oriented in a particular direction.
Other
forms of polarization include:
Linearly
or horizontally polarized: I.e. the E- vector is confined to one (horizontal) plane
---------à E
Vertically
polarized: I.e. the E- vector is confined to one (vertical)
plane
^
E
!
!
!
Circular:
The E-vector rotates through 360 deg
Elliptic:
any polarization not circular or plane.
B-mode polarization is much more complex and illustrated below.
Here, the E-vector (seen in line of sight) can curl either clockwise or
counter-clockwise into spiral patterns. It was precisely this type of pattern
that the BICEP 2 detected suggesting that both cosmic inflation and primordial
gravitational waves are real (since the latter are the only things known that
can give rise to the B-mode polarization)
The
graphic shown above, meanwhile, captures the swirling directions of light
within the cosmic microwave background.
Of
course, it goes without saying that other independent workers – researchers
will now have to confirm these findings if they are to be fully accepted. But
to this observer, it should only be a matter of time!
Technically speaking, the universe is not expanding just because the things in it are flying away from each other.
ReplyDeleteActually, it IS expanding given the space dimension is actually increase - now nearly 66 b light years in diameter.
ReplyDeleteThe way to visualize what's happening is to use or imagine a balloon with ink spots on it. Each ink spot represents a galaxy cluster. As the balloon is inflated each ink dot moves away from each other AND the balloon increases its dimension (radius) overall.
Our red shift measurements confirm the velocity of recession increases with distance of an object - and hence, yes, this is interpreted as cosmic expansion.