We humans are fascinated with the idea of traveling back or ahead in time time travel
machines and devices have been a staple for a lot of science fiction and even fantasy stories
catering to our desire to either change something in the past or make our lives better
or just skip ahead in time to find out if life gets better on its own in the future but despite
all of our technical and scientific advantages we are nowhere close to time travel or manipulation
we will probably never get to see for ourselves how mighty dinosaurs roam the earth
what living in ancient Egypt was like or what new organisms may evolve in the
future when humans are gone from the face of our dear planet ever wonder why we may never
develop a time machine because time probably doesn't even exist welcome to Factnomenal
and today let's find out why some physicists think time exists just in our heads
i apologize but we have to start this video in the most clinched wedding toast fashion
oxford dictionary defines time as the indefinite continued progress of existence and events
in the past present and future regarded as a whole but is that all that time is absolutely not
at least according to our physicists one of the most brilliant minds of our time Albert Einstein
proposed that time is the fourth dimension but one can argue that Einstein also theorized that
everything in the universe is relative so time can also be irrelevant in the best-selling book
the secret the authors write time is just an illusion but time and time again pun intended
physicists have proved that time is a measurable observable phenomenon but then again we also do
not know what makes time exist and be measurable so time is just our collective imagination
this question borders the realm of metaphysics and ontology as much as it does on the
strictly empirical questions about time that physics is well equipped to address however
there's no other way to say it physics as we know it is in crisis everything we know about
the universe could be wrong or misconceived for nearly a century physicists have explained the
universe with two wildly successful theories general relativity and quantum mechanics
quantum mechanics describes how things work in the incredibly tiny world of particles and
particle interactions general relativity describes the big picture of gravity and how objects move
the problem is that both theories even though they work exceptionally well in their own right
are in direct conflict with each other that's crazy right the two theories that we use as the
basis of explaining everything about the universe don't see each other eye to eye and that means we
could be wrong somewhere however it is also true that the nature of this conflict between quantum
mechanics and the theory of relativity is a bit controversial despite that the general consensus
among the scientific fraternity is that we need to replace both theories with something
new and more universal basically a theory that can explain both quantum mechanics and gravity
at the same time without pitting the two ideas against each other in essence such a theory would
explain how gravity's big picture works at the miniature scale of particles but that isn't easy
in fact producing a theory of quantum gravity is extraordinarily difficult now you may ask hey what
about string theory well that is a valid argument but string theory has its own set of difficulties
the problem with string theory is that it has various models of the universe but not a lot to
say that can be tested by experiments to figure out which model is the right one so in simple
words string theory just poses more questions than providing any proper answer and now if
you are thinking okay wait a minute what does that all have to do with time well everything
when string theory failed to provide the answers scientists began searching for answers elsewhere
during the 80s and 90s and came up with a range of new mathematical approaches to quantum gravity
the most prominent of these new equations was the loop quantum gravity see it got both quantum
and gravity covered but there was another remarkable aspect of the loop quantum gravity
it appears to eliminate time entirely the lube quantum gravity or lqg proposed that the fabric of
space and time is made of a network of extremely small discrete chunks or loops in the principia
newton distinguished two notions of time the first which he called the common one is the one in the
previous item the second which he called the true one is what has been later called newtonian time
newtonian time is assumed to be flowing uniformly even when nothing happens with no influence from
events and to have a metric structure in lqg newtonian time appears only as an approximation it
has no role at all in the foundation of the theory lube quantum gravity is not alone in abolishing
time a number of other approaches also seem to remove time as a fundamental aspect of reality
in 1927 sir arthur eddington coined the phrase the arrow of time in his book the
nature of the physical world what he meant by the term was the idea that time flows in only
one direction like a river but dimensions of space have no preferred directions or
orientations he also defined the arrow of time by pointing out three characteristics time is
vividly recognized by consciousness it is also equally insisted on by our reasoning faculty
determining that a reversal of the arrow of time would be nonsensical and lastly time makes no
appearance in physical science except in the study of the organization of a number of individuals
here the arrow indicates the direction of progressive increase of the random element
the last point here is what we can relate to the physicality of time or times arrow the
distinguishing factor of the arrow of time is that it points in the direction of increasing entropy
as explained in the second law of thermodynamics things in our universe decay as a course of
natural time-based processes but they do not spontaneously regain order without a lot of work
the part where eddington mentions that time makes no appearance in physical science
except in the study of the organization of a number of individuals is quite specific given
time occurs all over the place in physics time and entropy go hand in hand in a very distant past the
universe had a high degree of order which means the entropy was lowest and due to natural laws
entropy is continuously increasing or in simple terms one can say the arrow of time is entropy
apart from mentioning that time is just an illusion the authors of the
secret also mention that there is no time in the universe and there is no size for the universe
and what quantum physicists and einstein tell us is that everything is happening simultaneously
according to most scientists these statements are categorically false time is actually an integral
part of the universe the very linear concept of time is tied into the concept of the second law
of thermodynamics which is seen by many physicists as one of the most important laws
in all of physics without time as a real property of the universe the second law becomes meaningless
through his theory of relativity einstein proved that time by itself was not an absolute quantity
rather time and space are united in a very precise way to form space time and this space time is an
absolute measure that can be used again in a very precise mathematical way to determine
how different physical processes in different locations interact with each other einstein
firmly believe that past present and future do not happen simultaneously as would be the case
in absence of time in fact based on the evidence of his equation e equals m c squared einstein
knew that no information can travel faster than the speed of light if there was no time anything
could have been as fast as the speed of light which isn't the case every point in space-time
is limited in the way it can communicate with other regions of space-time the idea
that everything happens simultaneously exactly counters the results that einstein developed
lis mullen's 2013 book time reborn from the crisis in physics to the future of the universe argues
that often science does treat time as an illusion that is we need a theory that incorporates quantum
mechanics or quantum physics along with space-time and gravity and that's sometimes called the task
of quantum gravity einstein himself wrote to his friend michelle bessos's family on his passing
now he has departed the strange world a little ahead of me it signifies nothing for us believing
physicists the distinction between past present and future is only a stubbornly persistent
illusion many physicists argue that einstein's statement was not merely an attempt at consolation
einstein's position is implied by the two pillars of modern physics
einstein's masterpiece the general theory of relativity and the standard model of particle
physics the laws that underlie these theories are time symmetric that is the physics they
describe as the same regardless of whether the variable called at time increases or decreases
these physicists have made peace with the idea of a block universe arguing that the task of the
physicist is to describe how the universe appears from the point of view of individual observers
block universe is an idea of a static block of space-time in which any flow of time or passage
through it must presumably be a mental construct or other illusion but other physicists vehemently
disagree arguing that the task of physics is to explain not just how time appears to pass
but why for them the universe is not static the passage of time is physical lee smullen
for example wrote that we should treat time as a fundamentally real quantity and if we take it
seriously as such we will uncover laws of physics that evolve over time it remains to be seen if
this appeal will actually result in new insights into the foundations of physics tell us in the
comments do you think time is real or not and why and as always thanks for watching Factnomenal