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).

General Relativity

Published in 1916, the general theory of relativity is often regarded as Albert Einstein's greatest achievement and one of the most remarkable scientific contributions of the 20th century. It is known for redefining gravity beyond the previous Newtonian interpretation and describing it as a geometric property of space-time. General relativity is viewed as an expansion of the special theory of relativity and it differs from the special case because it takes into account the motion due to gravitational fields and other accelerating reference frames, thought to be similar according to the equivalence principle. Along with quantum theory, general relativity is considered to be a central pillar of modern physics and is currently accepted as the leading theory for gravitation.


Earth's mass warps space-time and shapes the Moon's geodesic orbit (Image: NASA).

General relativity describes the attractive force of gravity as being the result of an acceleration produced when something interacts with curved space-time, usually there because of an object with a very large mass. The more mass an object has, the more it warps the space-time around it and the larger its gravitational field is. Any object with some mass or just energy is thought to have a gravitational influence as well but will always experience an attractive pull when it is close enough to another object with a sufficient amount of gravity. Even rays of light that approach a gravitational field will bend towards it in a phenomenon known as gravitational lensing. This effect was confirmed to exist when the light from stars behind the Sun was observed to travel around it during the total solar eclipse of 1919.

Other tests of general relativity include the observation of a gravitational redshift in visible light emerging from a gravitational field, which loses energy and increases its wavelength, shifting towards a redder color. When entering a gravitational field, it behaves in the opposite way by gaining a shorter wavelength and a bluer appearance. Gravitational redshift was first measured in the light emitted by white dwarf star Sirius B in 1925. When a very massive object rotates on its axis, it will also twist the space-time around it as it spins. This is known as frame-dragging and it too was confirmed to exist by observing the orbital shifts that emerged from satellites traveling around our planet. General relativity predicts the existence of gravitational waves, which are ripples in space-time that propagate at the speed of light and are caused by sudden changes in an object's gravitational field, but their direct detection is currently a subject of on-going research.

From the smallest interaction of an elementary particle to the behavior of the cosmos itself, Albert Einstein's ideas have altered the way we view our physical surroundings on many scales. While general relativity accurately describes the gravitational attraction between celestial objects, it is additionally useful for describing other processes such as the expansion or contraction of a universe. Exotic objects such as black holes, white holes, and wormholes are also predicted to exist according to the equations of general relativity. Einstein's dream was to find a theory of everything that could combine the fundamental interactions of nature, specifically gravity and electromagnetism, to show that they were all facets of the same unified force. The search for a theory of everything continues to this day with the goal of bringing together Einstein's laws of general relativity with those of the quantum world in order to develop a consistent theory for quantum gravity.

Higgs Boson Found

In around December of 2011, preliminary research efforts began to hint at the presence of a new bosonic particle with Higgs-like properties. It was officially announced on July 4, 2012, by the ATLAS and CMS teams working at CERN, that these findings were definitely signs of something important. Regarded as the key to understanding the origin of mass, even the spark that caused the Big Bang, the new Higgs boson's unique yet brief appearance quickly became the object of joyous celebration worldwide as the excitation ripples of a particle collision revealed a signal, measuring near the 125-126 GeV mass-energy range, that had finally brought into reality the standard model particle predicted to exist since 1964.


Results consistent with the expected signature of the Higgs boson (Image: CMS).

Out of the four fundamental interactions known to exist: gravitation, electromagnetism, the strong nuclear force, and the weak nuclear force, it is believed that the exchange of a boson acting as a force carrier particle is what allows each kind of field or interaction to work. Just as the photon mediates the electromagnetic force, and the strong force gluon holds together particles inside the nucleus of an atom, the Higgs boson is responsible for converting Higgs field energy into corresponding elementary particles with mass.

Although fermions are the elementary particles that acquire mass to become the basic building blocks of ordinary matter, coupling with the Higgs field, an invisible energy condensate which permeates throughout everything and the vacuum of empty space, is also thought to give the weak nuclear force bosons: W+, W-, and Z, their exceptionally large masses. This process is due to a spontaneous symmetry breaking of the electroweak interaction, which sets apart the electromagnetic and weak forces, described to be unified parts of the same interaction only in an environment like that of the early Universe.

The level of certainty in this finding suggests that there is enough evidence to conclude a reasonably sound discovery. "A 5-sigma result represents a one-in-3.5 million chance of the result being noise. This is undeniable proof that a boson, with very Higgs-like qualities, has been discovered by the two detectors" (source). Along with being its own antiparticle, various other specific properties characterize the standard model Higgs boson, a few of which were accurately detected in the experimental results of this year. The recently found boson's rapid decay into the appropriate lighter particles, for example, serves as some evidence to label it the Higgs boson and to support the concept of the Higgs field. Future research efforts in this area may also clear the way for an new sector of physics entirely. "Supersymmetry provides both a natural context for the Higgs field and a possible explanation for the small but finite value of dark energy" (source). Known for its major innovations in modern science, the Large Hadron Collider's recent landmark achievement will serve as a crowning jewel for everyone who has patiently worked hard in anticipation of the new boson's arrival.

Particle Accelerator by CERN

Tonight, I write to express my interest in Earth's largest operating machine. The Large Hadron Collider is the most complex scientific instrument in use today. It is run by the European Organization for Nuclear Research (CERN) and it is buried 574 ft (175 m) below ground on the border of France and Switzerland, near Geneva, Switzerland.


The LHC can be found buried underground in Europe (Image: CERN).


The central LHC accelerating ring. It spans a 5.3 mile long (8.6 km) diameter (Image: CERN).

When powered up, the LHC releases beams made up of protons or other ions through a series of interconnected ring-shaped tunnels. Accelerated by giant superconducting magnets, the particles reach speeds approximating 99.9% the speed of light. As they approach the largest ring (highlighted in yellow), which is nearly 17 mi (27 km) in circumference, engineers collide the particles in testing rooms the size of warehouses. Results are then recorded by sensors placed in these rooms and studied in order to provide useful information about the nature of the particles that belong to the standard model of particle physics. Scientists and engineers examine the results of current research efforts either to try to prove the existence of the Higgs boson, the key to the origin of mass in the universe, or to gain additional knowledge regarding the dynamics of subatomic particles.


Engineers working inside the LHC (Image: CERN).

Engineers have been maintaining and upgrading the LHC ever since achieving the first successful particle beam circulation in September of 2008. This year, on March 30, 2010, the LHC broke the record for the highest-energy man-made collision event ever planned between two 3.5 teraelectronvolt beams. It might also be able to shed light on the unification of fundamental forces, such as that of the electroweak interaction, found at very high temperatures. With a maximum operating energy of 14 TeV, the LHC is set to advance a new era in physics over the next few years.