Time is not a line but a dimension, like the dimensions of space.... Part 2

In July 2019, the Independent 7 had an article about scientists in Oak Ridge National Laboratory in eastern Tennessee hoping to open the first portal to glimpse a parallel universe, a shadowy dimension which could be identical in many ways to our own, with mirror particles, mirror planets and possibly even mirror life. The TV series 'Sliders' used the parallel universe theory as the backdrop to their storylines. A scientist working on an antigravity machine, accidentally created a portal in the form of a vortex-like wormhole to "slide" to a parallel universe, activated by a handheld timer device. He and his comrades prematurely used the timer to escape a dangerous situation, causing the timer to lose track of the coordinates for their home universe. The series recounts their adventures as they slide between different parallel Earths, trying to find their way back home.

Again, in 2019, New Scientist 8 reported that, using Bell's theorem, some ideas about the quantum world appear to suggest there are many versions of 'you' spread out across these many parallel universes. John Stewart Bell's 1964 paper entitled "On the Einstein-Podolsky-Rosen Paradox" 9 showed that local hidden variables of certain types cannot reproduce the quantum measurement correlations that quantum mechanics predicts. The theory of quantum entanglement predicts that separated particles can briefly share common properties and respond to certain types of measurement as if they were a single particle. In particular, a measurement on one particle in one place can alter the probability distribution for the outcomes of a measurement on the other particle at a different location.

As recently as the 8th April 2020, New Scientist magazine 10 reported that strange particles observed by an experiment in Antarctica could be evidence of an alternative reality where everything is upside down, and it may be indicative of a parallel universe going backwards in time. In the article, it claims a thorough analysis has determined that particles spotted by a giant balloon in Antarctica can’t be explained by our current understanding of physics and the race is on to figure out what they are.

Time travel — moving between different points in time into the past or future — has been a popular topic for science fiction for decades. Doctor Who, Primeval, Star Trek, Back to the Future, The Time Machine, The Terminator, Planet of the Apes, Déjà vu, Edge of Tomorrow, About Time and The Time Traveller's Wife are just a handful of the dozens of films and TV shows that have seen humans journeying to the past or future. Each one comes with their own time travel theories. 11

Some general relativity spacetime calculations, that permit travelling faster than the speed of light, suggests time travel to the past is theoretically possible. This is through means such as cosmic strings (hypothetical one-dimensional defects in space-time), traversable wormholes (a tunnel in space that is believed to connect different parts of the universe), and Alcubierre drives (a spacecraft would traverse distances by contracting space in front of it and expanding space behind it, resulting in effective faster-than-light travel) 12. Not all scientists believe that time travel is possible. Some even say that an attempt would be fatal to any human who chooses to undertake it.

Time travel brings up paradoxes that break the laws of physics by creating potential logical problems and inconsistencies that would arise if a person were to travel to a past time and change it, such as the Grandfather or Grandmother Paradox: a person travels to the past and kills their own grandfather or grandmother before the conception of their father or mother, which prevents the time traveller's existence. So, the time traveller is not in existence to travel to the past and kill their own grandfather or grandmother, and therefore they are born. If time travel is possible, it somehow must avoid such a contradiction. 13

Anomalies created by the grandfather paradox doesn't necessarily mean that time travel is impossible. One set of reasoning that has been suggested is branching universes, i.e. the universe we are in splits with each instance of time travel, creating two different universes, allowing similar timelines to run alongside one another creating the previously discussed multiple parallel universes 14 This was very strongly used in Back to the Future, the trilogy of which ultimately created no less than 8 timelines. According to Dr. Emmett Brown in Back to the Future Part II, whenever a time traveller alters key events occurring in the past, they effectively bring an alternate timeline into existence at their point-of-entry. 15

It is generally understood that travelling forward or back in time would require a device — a time machine — to take you there. Time machine research often involves bending space-time so far that timelines turn back on themselves to form a loop, technically known as a "closed time-like curve."

Research by the theoretical physicist Amos Ori at the Technion-Israel Institute of Technology in Haifa is exploring the concept of using a donut-shaped hole enveloped within a sphere of normal matter. Using focused gravitational fields, space-time could get bent upon itself inside this donut-shaped vacuum to form a closed time-like curve. A traveller racing round inside the donut would be able to go further back into a past time with each lap.

"The machine is space-time itself," Ori said. "If we were to create an area with a warp like this in space that would enable timelines to close on themselves, it might enable future generations to return to visit our time."

Ori emphasized one significant limitation of this time machine—"it can't be used to travel to a time before the time machine was constructed." 17

References

7. https://www.independent.co.uk/news/science/parallel-universe-portal-mirror-world-science-stranger-things-oak-ridge-a8987681.html

8. https://www.newscientist.com/article/2213756-a-classic-quantum-theorem-may-prove-there-are-many-parallel-universes/

9. https://en.wikipedia.org/wiki/John_Stewart_Bell#Bell's_theorem

10. https://www.newscientist.com/article/mg24532770-400-we-may-have-spotted-a-parallel-universe-going-backwards-in-time/#ixzz6LxG22gHE

11. https://www.space.com/21675-time-travel.html

12. https://www.reddit.com/r/timetravel/comments/dtfu0i/time_travel_to_the_past_is_theoretically_possible/

13. https://www.space.com/grandfather-paradox.html

14. https://www.newscientist.com/article/2227304-time-travel-without-paradoxes-is-possible-with-many-parallel-timelines/

15. https://backtothefuture.fandom.com/wiki/Back_to_the_Future_timeline

16. https://www.livescience.com/1817-time-travel-machine-outlined.html

17. Full article in Physical Review D Journal. https://journals.aps.org/prd/

Time is not a line but a dimension, like the dimensions of space.... Part 1

What, then, are time and space? Space and time are the most fundamental features of our universe, and yet they are also the most puzzling. Are there alternative parallel worlds and universes with their own Earth's with alternate histories? Might time travel be possible? Can you bend space and similarly bend time also, so that you could move faster than light and travel backward in time to exist in two places at once? Could time go backwards? Or are time and space an illusion, essentially just a human invention?

Wikipedia defines time as "the indefinite continued progress of existence and events that occur in an apparently irreversible succession from the past, through the present, into the future."1 Our human ancestors, (and some other cultures today) viewed time as cyclical, circadian, seasonal and rhythmic, matching with the Circle of Life. Physicists have many different ways of conceptualizing time: Albert Einstein showed that time is an illusion; it is relative and can vary for different observers depending on the particular observer's speed through space.

Chronometry, or the measurement of time, takes two forms: the calendar for periods of over 24 hours and the clock for periods of up to 24 hours. In 1752, 11 days went missing and as a result, 3-13^th September 1752 never existed. It would be great to have some amazing time travel story to explain this away. However, the mystery of the missing days was drearily due to Britain abandoning the Julian (Old Style) calendar in favour of the Gregorian (New Style), so 3 September instantly became 14 September. 2 An agreement on the nature of time became increasingly necessary with the launch of the industrial revolution; Greenwich Mean Time, created in 1847, was used by British railways, the British navy, and the British shipping industry. This was calibrated to the mean solar time, the hour angle of the mean Sun plus 12 hours, at Greenwich Royal Observatory.1

Is the universe we live in the only one out there with its unique 'rules' about Spacetime? Scientists can't be sure what the configuration of space-time is, but as there are a finite number of ways particles can be arranged in space and time, it is thought that it must start repeating at some point. The Many-Worlds Theory says that anything that could have ever happened and anything that will ever happen all separately and simultaneously exist in different parallel worlds and timelines and gives rise to the possibility of many more dimensions to our world than the three of space and one of time that we know. Quantum mechanics describes the world in terms of probabilities, rather than definite outcomes, with the mathematics suggesting that all possible outcomes of a situation could occur — in their own separate universes. 3

A parallel universe, also known by a bewildering array of other terms: alternate universe, alternate reality, alternate timeline, alternate dimension, dimensional plane, interpenetrating dimension, parallel dimension, parallel world, parallel reality, quantum universe or quantum reality, is a hypothetical self-contained plane of existence, co-existing with one's own. The entirety of all theoretically potential parallel universes that constitute reality is often termed a “multiverse", with a hypothetical group of multiple universes comprising everything that exists: the entirety of space, time, matter, energy, information, and the physical laws and constants that describe them.

The American theoretical physicist and string theorist Brian Greene discussed nine types of multiverses Quilted, Inflationary, Brane, Cyclic, Landscape, Quantum, Holographic, Simulated or Ultimate.4 He and Max Tegmark devised classification schemes for the various theoretical types of multiverses and universes that they might comprise which I will summarise thus: Level I: An extension of our universe, Level II: Universes with different physical constants, Level III: Many-worlds interpretation of quantum mechanics, and Level IV: Ultimate ensemble. 5 A lot of scientists are generally sceptical but Professor Stephen Hawking was a proponent of the multiverse hypothesis and possible evidence has come to light in the last few years, suggesting this is in fact may be a reality.

In 2017, there was an article in the New York Post 6 stating that some scientists believed they may have discovered evidence of a parallel universe that crashed into our own in "a galactic impact mirroring a car crash". That impact was so incredible, according to this research, that it pushed energy out of a huge region of space, resulting in a Cold Spot. Since 2004, when it was first spotted by NASA, scientists have been baffled by the discovery of this unusually cold region of space, which is 1.8 billion light years across and colder than its surroundings. It was originally thought the region might have been colder because it had 10,000 fewer galaxies than other areas of the same size. However, researchers at Durham University now believe it could be the first evidence of a “multiverse.”

References

1. https://en.wikipedia.org/wiki/Time

2. http://www.projectbritain.com/calendar/September/calendar.html

3. https://www.space.com/18811-multiple-universes-5-theories.html

4. http://everything.explained.today/Multiverse/

5. https://infogalactic.com/info/Multiverse

6. https://nypost.com/2017/05/18/scientists-think-they-found-proof-of-a-parallel-universe/ (originally published by News.com.au)