Dark Energy, The CMB, & String Theory

The photonic emission of the Cosmic Microwave Background radiation that happened about 380,000 years after the Big Bang provides a unique way to understand the emission of energized particles in every direction from a totally opaque and dense universe, which is similar to a plasma with no atoms. According to the holographic principle, if one wants to visualize something like dark energy as the driving force behind the expansion of our universe, then this event and its existence within at least the 5th dimension, which is the place where cosmic superstrings exist, space-time is curled up into a tiny 6-dimensional loop, and gravity is unified with the electromagnetic force, should be genuinely explored.

The CMB was first detected by the Holmdel Horn Antenna in 1964. The accelerating expansion of our universe through dark energy was originally conjectured in 1921, along with Kaluza-Klein theory as a precursor to string theory. Among this radiation one can find that the universe at its birth emitted many different kinds of particles, including lots of energy and matter. Both dark energy and the relic radiation can be measured together and directly related to each other due to the wavelengths of light that eventually red-shift over time. Today, the CMB sits around us everywhere in the sky as a microwave echo of energy from the abyss that was once emitted by the universe when it was only in its youth.

Dark energy, similar to vacuum energy in otherwise empty space, is thought to expand space from every point and in every direction. The CMB's photons emerged from a dark universe the same way as dark energy expands the particular space that it's inherent to. Experiments such as the Fermilab Holometer are currently working to find evidence that would show the universe itself is a giant hologram. This would eventually shed light on dark energy and also support modern interpretations of string theory, including M-theory, with its 11 dimensions of reality.


A 6-dimensional Calabi–Yau manifold, as known to superstring theory and mirror symmetry (Image: Wolfram).

Primordial Gravitational Waves

On March 17, 2014, it was officially announced that signs of gravitational waves, or ripples in the fabric of space-time, had been discovered in the data collected from the Cosmic Microwave Background radiation as an imprint left by our Universe approximately 380,000 years after the Big Bang. This is considered to be a plausible advance towards the indirect detection of Albert Einstein's gravity waves, originally predicted to exist in his general theory of relativity of 1916. The BICEP2 team, located at the South Pole, has identified a swirling pattern throughout the light of the CMB known as B-mode polarization, believed to be the result of inflationary gravitational waves. "We’ve found the smoking gun evidence for inflation and we’ve also produced the first image of gravitational waves across the sky" (source).


A polarized light pattern in the CMB caused by early gravitational waves (Image: BICEP2).

Finding gravitational waves embedded in the CMB would reasonably support the theory of inflation, originally proposed by physicist Alan Guth, which describes an initial period of highly accelerated expansion for the Universe that smoothed out irregularities in space-time and made the cosmos look almost the same in every direction. The CMB is the oldest electromagnetic radiation we can see from after that period, thought to have emerged at a time when matter was only beginning to form structures out of a hot and dense plasma. This early light now fills every region of space and reaches us in the form of microwaves with an average temperature of 2.725 K, while it is considered to be the Big Bang's afterglow. Along with providing important information about the universe's early development, including tentative effects of ancient gravity waves, the CMB also reveals key insights into features of today's universe such as apparent composition and overall uniformity.

Special Note: Although there is new evidence suggesting that interstellar dust levels may have modified the interpretation of these results by being higher than previously determined, the theoretical basis for gravitational waves is still very strong and this latest outcome does not completely rule out their existence. 8*]