Unifying approach of science
Today modern science has reached to an unbelievable level . whose an latest example is (large hadron collider).
L.H.C.
The biggest and most complicated paticle physics experiment ever seen is nearing completion . the lhc will accelerate bunches of protons to highest energies at nearly the speed of light
Fast facts of lhc
Proton velocity -99.9999999991% of light
Proton per bunch - upto 100 billon
No of bunches – upto 2,808
Bunch crossings per seconds –upto 31 millons at 4 locations
Collisions per bunch crossing – upto 20
Data per collision – about 1.5 megabytes
No of higgs particles – 1 every 2.5 second
Each proton will have about 7 tev of energy -7,000 times as much energy as a proton at rest .
At this collision and energy level scientist are expected to occur higgs particles (believed to be responsible for imbuing other particles with mass ) and the particle that constitutes the dark matter that makes up most of the material in the universe .
Five goals for the LHC-
1- Rediscover the standard model - the first goal of the collider is not to probe the new but to confirm the old .the machine will produce familiar particles in prodigious numbers (several top quarks per second ,for example) and scrutinize them with increasing refinement . not only does this test the machine and its instruments , its sets precise benchmarks for determining whether new phenomena are indeed new .
2- Determine what breaks th+e +electroweak symmetry - the collider will seek the higgs boson determine its properties . does the higgs provide mass not only to the W and Z particles but also to the quarks and leptons?
3- Searches for new forces of nature- new force particles would decay into known the particles such as electrons and their antimatter counterparts positrons . such forces would indicate new symmetries of nature and might guide physicists toward a unified understanding of all the interactions .
4- Produce dark matters candidates – by observing neutral ,stable particles created in high energy collisions , the collider could help solves one of astronomy’s great puzzles and test Researcher’s Understanding of the history of the Universe.
5- Above all explore - the collider will examine its immense new domain for evidence of hidden spacetime dimensions ,new strong interactions , supersymmetry and the totally unexpected .physicists will have to be attentive to connections among today’s great questions and alert to new questions the collider will open up;
Thus we can say that goal of LHC is to find the Higgs Boson and supersymmetry.
Higgs boson- firstly professor Higgs had proposed the higgs field theory that every particle has a mass because they interact with an invisible field and we call it higgs field .
Heavier particles interact with forces while light does not interact ( so light has no mass ).
SuperSymmetry – It predicts that there can be a supersymmetrical partner of every known particle . problem is that we see only one partner.
So Concept of LHC is mainly related to the two part of physics “1-Particle physics , 2- Theortical physics .
THEROTICAL PHYSICS-
This first pillar of this physics is einstein’s 10 tensor field partial differential equations based upon higher mathematics known as Tensor Calculas . These equations are a set of 10 equatons in einstein’s theory of general relativity which describe the fundamental interaction of gravitation as a result of spacetime being curved by matter and energy.
Einstein’s field equations are solutions of spacetime . the study of exact solutions of EFE is one of the activities of cosmology . it leads to prediction of black holes and the expanding universe . dutch physicist willem de sitter solved the equations of general relativity for a simplified universe incorporating einstein’s cosmological constant.
Einstein’s equations predict that universe has to expand or contract so from this realization the Big Bang Theory was born .
The next pillar came in 1920s , when an American astronomer vesto sipher detected the expansion of the universe and who used the spectra of stars to measure the velocities of nearby galaxies . waves of light from a star moving toward earth are compressed , shortening the wavelength and making the light bluer . light waves from a object moving away from us are stretched , making the wavelength longer and the light redder . by measuring the lengthening or compression of the light waves from galaxies , sipher was able to determine whether they moving toward us or away from us and at what speed sipher found that almost all these galaxies were moving away from us .
Later the person who is generally credited for discovering the expansion of the universe is not sipher but American astronomer Edwin hubble . hubble determined not just the velocities of nearby galaxies but also their distances. His measurements led to two conclusions that justify his fame. First , hubble showed that galaxies were so far away that they were really independent collections of stars, just our own galaxy. Second he discovered a simple relation between the distances to galaxies and their velocities. The velocity was directly proportional to its distance from us . a galaxy twice as far away as another was moving twice as sadt.
The Third Pillar Is the fiant glow of the cosmic microwave background , discovered in 1965 by bell labs physicists arno Penzias and and roberet willson as they tracked down sources of radio interference . this radiation was quickly recognized from the early stages of the expansion of the universe . it indicates that the universe began hot and dense and hence has since cooled and thinned out .
The final observationol pillar of the Big Bang is that the hot , dense early universe was a perfect location for nuclear fusion when the temperature of the universe was one billon to 10 billion kelvins , lighter nuclei could fuse into heavier nuclei , a process known as Big Bang nucleosynthesis . this process can occur for only a few minutes as the universe expands and cools , so fusion was limited to the lightest elements .
Today Theortical Physics want a theory of quantum gravity or theory of every thing .
Einstein’s general theory of relativity says that the universe began with theBig Bang singularity a moment when all the matter we see was concentrated at a single point of infinite density .but the theory does not capture the fine quantum structure of spacetime, which limits how tightly matter can be concentrated and how strong gravity can become . to figure out what really happened , physicists need a quantum theory of gravity.
According to one candidate for such a theory , loop quantum gravity , space is divided into “atoms” of volume and has a finite capacity to store matter and energy , thereby preventing true singularities from exiting.
Theories of Quantum Gravity
1- Loop Quantum Gravity- gravity is typically an attractive force . but loop gravity suggests that the atomic structure of spacetime changes the nature of gravity at very high energy densities ,mking it repulsive . imagine when energy densities become too large , repulsive force come into play. The continous space of general relativity ,in contrast , can store a limitless amount of energy. In fact , the repulsive gravity caused space to expand at an accelerate rate.
It Invokes a new technique for applying quantum rules to einstein’s general theory of relativity.
2- String Theory – The Approach favored by most therotical physicists , it is a theory not just of quantum gravity but of all matter and forces . It is based on the idea that particles (including the hypothetical ones that transmit gravity ) are vibrating strings.
PARTICAL PHYSICS
The first pillar is quantum field theory. Which describes that everything is field . This theory proposed the field quanta necessarily the chunked ripples in a field that look like particle.
A boost to Quantum Field Theory came with Dirac Equation , a single particle equation which obeying both relativity and quantum mechanics . but this theory had some difficulties . to overcome these difficulties in 1940, An Gauge theory became produced. Which is known as the Standard Model of Particle Physics.
This model predict that Electromagnetic force is caused b/w two electrons by an exchange of Photons , Weak nuclear force by exchange of Bosons(W-, W+, Z) AND Strong Nuclear forces by 8 gluons.
And for gravity this theory assumed that Graviton particle appears.
The guiding principal of the standard model is that its equations are Symmetrical . All Other equations related to this are also Symmetrical .
These Symmetries beget forces that are carried by special particles called bosons.
Physicists want to unify the Strong , Weak Nuclear Force and Electromagnetic Force.
Later the theory of ELECTROWEAK FORCES as formulated by Sheldon Glashow , Steven Weinberg and Abdus Slam , who won the 1979 Nobel Prize in physics for their efforts .
The Weak Force , which is involved in radioactive beta decay , does not act on all the quarks and leptons . Each of these particles comes in mirror –image varieties , termed left-handed and right-handed , and the Beta decay Force acts only on the left-handed ones a striking fact still unexplained 50 years after its discovery. The family symmetry among the left-handed particles helps to define the electroweak theory.
In the initial stages , the theory had two essential shortcomings . First , It foresaw four long-range force particles –referred to as gauge bosons where as nature has but one : the photon.
The Other three have a short range less than about 10 root -17 meter. According to Heisenberg’s Uncertainty Principle , this limited range implies that the force particles must have a mass approaching 100 billon electron volts (Gev).
The second shortcoming is that the family symmetry does not permit masses for the quarks and leptons , yet these particles do have masses.
So we need to recognize that a symmetry of the laws of nature need not be reflected into the outcome of those laws.
Physicists Says “that the Symmetry is Broken”.
Later the inspiration came from a seemingly unrelated phenomena : SuperConductivity , in Which certain materials carry electric current with zero resistance at low temperatures . although the laws of electromagnetism themselves material is not. A photon gains mass within a superconductor. Thereby limiting the intrusion of magnetic fields into the material .
This problem is a perfect prototype for the electroweak theory . If Space is filled with a type of superconductor that affects the weak interaction rather than electromagnetism, it gives mass to the W and Z bosons and limits the range of weak interactions
