Evidence of collision with another universe during the early formation of our universe

If our universe slammed into a neighboring one during a growth spurt in its first second, the collision would have left a mark. Half of the young cosmos was slightly coarser than the other.

Details about the Higgs Boson also suggest that there is a multiverse.

““When they smack into each other, there’s kind of a shock wave that propagates into our universe,” said Kleban, an associate professor of physics at New York University. Such a shock wave — if that’s what the image shows — would be evidence in support of the multiverse hypothesis, a well-known but unproven idea that ours is one of infinite universes that bubbled into existence inside a larger vacuum.

The asymmetry of our universe appears in the cosmic microwave background — the staticky afterglow from the moment the universe became transparent, 380,000 years after the Big Bang. The fog of charged particles that until then had enshrouded the cosmos cooled down enough to congeal into neutral atoms, freeing light to travel unimpeded through space for the first time. Over the past three years, the European Space Agency’s Planck satellite captured a 50-megapixel image of this light coming from all directions, each photon imprinted with a record of the temperature where it originated more than 13 billion years ago.

Some cosmologists chalk it up to a statistical fluke. The odds that quantum fluctuations at the birth of the universe could have randomly generated the observed asymmetry are between 0.1 and 1 percent — about the same as a repeatedly tossed coin coming up heads eight times in a row.

Cosmologists have already advanced several competing theories to explain how events during and immediately after the Big Bang could have carved this asymmetry into the cosmos.

Few believe the toy model, with its inflation field plopped into place, can fully explain what jumpstarted the universe. Instead, the field could be one of the extra, curled-up dimensions of space that are postulated by a hypothetical “theory of everything” called string theory, which would likely involve more than one inflation field. In a paper posted to the physics preprint site arXiv.org in May, John McDonald, a cosmologist at Lancaster University in the United Kingdom, showed that a two-field model could have caused the asymmetry in the cosmic microwave background as long as the second field, called a curvaton, decayed after inflation ended and after the formation of dark matter.

An unexplained feature appears in the Planck satellite image of the early universe: At the largest scales, temperature fluctuations are more extreme in the half of the sky to the right of the gray line than to the left. (Image: ESA and the Planck Collaboration)

Arxiv – Planck 2013 results. XXIII. Isotropy and Statistics of the CMB

Lacking a theory of how physics works at the extremely hot and small scales that existed in the newborn universe, they currently have only a simple “toy model” of the event: An inflation field permeating all of space transitioned to an unstable state approximately 10-36 seconds after the Big Bang, causing space to balloon 1078 times in volume before the inflation field restabilized about 10-30 seconds later. According to this model, the cosmos should have stretched evenly, producing a uniformly random, speckled pattern of hot and cold in the cosmic microwave background. But that’s not what the data suggest.

It is expected that the polarization data that will become available with the 2014 data release should provide valuable information on the nature of the CMB anomalies. Then, the presence, or even absence, of a specific signature in the data should help to elucidate the physical mechanism that is causing the anomaly.

The two fundamental assumptions of the standard cosmological model – that the initial fluctuations are statistically isotropic and Gaussian – are rigorously tested using maps of the CMB anisotropy from the Planck satellite. The detailed results are based on studies of four independent estimates of the CMB that are compared to simulations using a fiducial $Lambda$CDM model and incorporating essential aspects of the Planck measurement process. Deviations from isotropy have been found and demonstrated to be robust against component separation algorithm, mask and frequency dependence. Many of these anomalies were previously observed in the textit{WMAP} data, and are now confirmed at similar levels of significance (around $3sigma$). However, we find little evidence for non-Gaussianity with the exception of a few statistical signatures that seem to be associated with specific anomalies. In particular, we find that the quadrupole-octopole alignment is also connected to a low observed variance of the CMB signal. The dipolar power asymmetry is now found to persist to much smaller angular scales, and can be described in the low-$ell$ regime by a phenomenological dipole modulation model. Finally, it is plausible that some of these features may be reflected in the angular power spectrum of the data which shows a deficit of power on the same scales. Indeed, when the power spectra of two hemispheres defined by a preferred direction are considered separately, one shows evidence for a deficit in power, whilst its opposite contains oscillations between odd and even modes that may be related to the parity violation and phase correlations also detected in the data. Whilst these analyses represent a step forward in building an understanding of the anomalies, a satisfactory explanation based on physically motivated models is still lacking.

SOURCES – Simons Foundation and Arxiv

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