**Space and Outer Boundaries of the universe**

Current data suggest that our universe is expanding. The expansion hints to a boundary between universe and the entity that exists out of the edges. By definition such an entity cannot be space-like. Therefore space should end at such an interface.

#### Space and Microcosm

Space gets pale at smaller scales. It turns choppy and unstable. The smallest size of space that can be meaningful is Planckian size. Planck distance is 1.6 X 10^{-33}cm. Inside the Planck holes space cease to exist. Formerly I have postulated that Planck holes represent internal boundaries of space-time universe.

#### Time and Microcosm

Time-energy uncertainty is an extension of the Heisenberg uncertainty principle. The uncertainty principle governs at smaller scale,

ΔE (energy) × ΔT(time) ≥ h(Planck Constant)/ 2π

The above principle is fundamental. The problem is not because our measurement apparatus is not sensitive enough. It happens because in smaller scales the notion of time becomes scrambled and it is interchangeable with energy. In smaller scales even long before we come to Planck Time, the notion of time gets blurry and vague.

#### Compton Scattering

Compton scattering refers to the way a photon strikes and scatters from an electron. The illustration shows two of many different Feynman diagrams representing possible scenarios for the meeting between a photon and an electron.

According to Richard Feynman, all these scenarios are valid and simultaneously happening in the event. In the second diagram, we see the distortion of time at the infinitesimal instant of the collision. In this diagram, time reverses; in other words, the particles scatter from each other before they even collide. The diagrams indicate how the sequence of events in a microcosm gets mixed up.

What is the time scale for Compton scattering? If the energy of the incoming photon were 100 keV, then the intermediate state would last for 6.6 × 10^{-21} seconds.This is still many times longer than time limitation imposed by the Planck unit of 10^{-43} seconds. In comparison to Planck time, it is a very long dusk, like a fall sunset in the North Pole. In fact, Feynman diagrams of Compton scattering suggest infinite expressions representing infinite ways that an electron and a photon can interact. All these possible ways are happening in a very short time. These different possibilities cannot simultaneously happen in our space-time. Various laws inside space-time, such as the law of conservation of energy, will not allow this to happen. For these infinite possibilities to take place, we need a domain with an infinite amount of energy, which is also not bounded by time. Alternatively, we may postulate that all diagrams are represented in informational domain.

In addition, beyond the smallest possible fraction of time (Planck time), time ceases to exist.

**Time and Macrocosm**

At the large scale, we can look at a light cone initiating at the Big Bang and extends to this moment. Therefore, we may claim that the outer boundary of time is now, approximately 14 billion years away from the Big Bang moment.

Time has not yet reached beyond this instant. All we can foresee beyond this moment are potentialities. The possibilities are determined purely by the existing data and available energy, the two elements that we have assumed for the singularity. Can we then conclude that in the outer limit of time we face singularity?

In addition, according to Einstein’s special theory of relativity, as an object accelerates to relativistic speeds (speeds approaching the speed of light), time slows down. Once in proximity of this speed, time will dilate and eventually disappear. Brian Greene writes:

“The maximum speed through space occurs if all of an object's motion through time is diverted to motion through space … but having used up all of its motion through time, this is the fastest speed through space that one object—any object—can possibly achieve.”^{[6]}

Therefore, if we are traveling at full speed (i.e., the speed of light) in space, we are not traveling in time dimension at all. Here, we may conclude that time cease to exist at the limits.

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