Diverse Quantum Field Theories and inter-related issues are presented here, accompanied by associated questions, philosophical discussions, and insights احسن جامعة فى مصر. This article includes among others, discussion about the beginning of our universe, time-space observations, and the non-deterministic needs for actual experiments to prove theories in physics, specifically the possibility to ascertain the existence of an object in space without necessarily interacting with it. Part of the issues discussed here is more philosophical rather than in the realm of theoretical physics.
Special relativity was introduced in 1905. It tells us how motion, time, and velocity are relative to the observer and they are not absolute. Also, we know that particles cannot exceed the speed of light. General relativity, which was introduced in 1915, is about gravity and tells us how space-time is bent due to mass while affecting particle motion.
Quantum Physics explains the interaction between particles, which constitute the matter and their related forces, namely, it explains how everything works. Einstein was among the first physicists who described the evolution of ideas from early concepts to relativity and quanta  and the introduction of gravitational waves .
There are three forces that matter interacts with: electromagnetism, which explains how atoms hold together, the strong nuclear force, which explains the stability of the nucleus of the atom, and the weak nuclear force, which explains the radioactive decay of some atoms. These three theories were assembled under the umbrella called the standard Model of particle physics. The problem with this model was that it did not explain why matter has mass.
Almost everybody agrees that the universe had a definite starting point. Some physicists believe that the actual point or time of creation cannot be explained by the currently known laws of physics. We are aware of the existence of gravitational waves that are caused by movements of large masses. Those waves were predicted by Einstein and they are included in his theory of general relativity.
13. 8 billion years ago, the Big Bang occurred . Accordingly, this is the distance that the observable universe may extend, which is 13. 8 billion light-years. We may assume further that the space-time beyond that distance might be another universe and so there might be multi-universes or multiverse. We may argue about the Big Bang that generated our universe. What if there was more than one Big Bang? This assumption may lead to the existence of a multiverse.
A new era for the understanding of our universe may be started recently by the discovery of Higgs boson. A boson is a type of subatomic particle that imparts a force. Peter Higgs tried to explain why certain particles have mass and others do not have mass and they float in the universe like photons of light. According to Einstein, E=mc^2 which means that energy and mass are equivalent to one another, that is mass m=E/c^2 accordingly, if we add enough energy we may create mass. We have had endless debates about how the universe began and what was before that. My assumption based on many arguments is that the only way we do not violate any conservations laws is to assume that our universe was created out of nothing. There might be another theory that supports the idea that there’s no end or beginning to the creation of our universe.
We use the word time directly and indirectly very often in our daily conversation and throughout our lifetime: time is money, time of life, time after time, between times, gain/loss of time, good/bad time, slow/fast time, right/wrong time, before/after time, present time, past time, real-time, on time, in no time, kill time, any time, every time, plenty of time, timeless, time limit, time cycle, time cures, and time flies…
Time is depicted by artists in various ways, among them the famous ‘melting clocks’ by Dali. We can distinguish between pure time, relative time, and absolute time. Time measurement is the unit of time to which all time measuring devices ultimately refer to. It is a point at or a period in which things happen, a repeated instance of anything or a reference to repetition, the state of things at any period.
Space is that part of the boundless four-dimensional continuum in which matter is physically rather than temporally extended. Relativity recognizes the impossibility of determining absolute motion and leads to the concept of a four-dimensional space-time continuum.
The special theory of relativity, which is limited to the description of events as they appear to observers in a state of uniform motion relative to one another are developed from two axioms: The law of natural phenomena is the same for all observers and the velocity of light is the same for all observers irrespective of their velocity. Space and time in the modern view are welded together in a four-dimensional space-time continuum.
There is no clear distinction between three-dimensional space and independent time. Time means different things to different ‘observers’. This may not agree with the axioms (on which the special relativity theory is based) described earlier, at least not from a psycho-philosophical point of view.
These ‘observers’ may include people (humans), animals, plants, clocks, and other beings outside our time universe. Time seems to be different for different people: age, education, origin, mental stage, and religion may all affect. Time appears ‘slow’ when we are young and ‘fast’ as we grow older. Time seems to be passing faster when we are enjoying ourselves or when we are busy, as opposed to when we are bored or idle. The description of time-related events in the history of humankind differs in different cultures.
Clocks and other similar instruments measure time and tend to be almost identical in terms of information about it. This is to be expected as we designed them all to measure time defined to be consistent within our universe. Time is continuous concerning our universe and within it, and it is relative to our observations. When we observe a moving object between two points we ‘see’ it traveling all the distance between the two points, so we assume that this continuity of observation means that time is continuous. This may not be the case, however, if we perform our observation in another galaxy or in another dimension, where these rules are not necessarily valid. In the digital domain, as opposed to the analogue domain, we may observe the same continuity of moving objects. The time is digitized, however, and between two consecutive time points there is a gap of a certain fraction of a time unit, equivalent to the sampling resolution, where ‘anything might happen’.
For other creatures, these time gaps may represent their entire lifecycle, or we may be living within our time with another life form, whose time resolution fits with our ‘dead times’, which are our time gaps. Television is viewed as continuous moving pictures, whereas actually, it comprises discrete individual pictures, projected at thirty frames (or more) or pictures per second. Time can be measured, viewed, and evaluated. The observer’s tools for the evaluation of time are his/her senses. Unfortunately, senses can be fooled.