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00:00For the whole of human history, we've been able to explore reality in three spatial dimensions
00:05and one temporal.
00:07Everything we know is guided by these fundamental rules.
00:10But for some truly outside-of-the-box thinking, we could ask, what if there's more than
00:16just length, width, height, and time?
00:19In the modern day, the search for extra dimensions is clearly alive and kicking, to the point
00:24where some believe that we should already be adding another to our established bank
00:28of four.
00:29This is Unveiled, and today we're answering the extraordinary question, did scientists
00:34already discover a fifth dimension?
00:36Do you need the big questions answered?
00:38Are you constantly curious?
00:40Then why not subscribe to Unveiled for more clips like this one?
00:43And ring the bell for more thought-provoking content!
00:46In everyday life, we navigate three familiar dimensions – length, width, and height.
00:51The physical reality surrounding us is made up of and realized thanks to these three fundamental
00:56points of reference.
00:58Additionally, time is considered the fourth dimension, because as it moves forward linearly,
01:03it also assumes a crucial role in how we perceive reality.
01:07We can always find a measure for all four dimensions, but we all move through time at
01:11the same rate, rather than being able to freely move through it like we can with the spatial
01:16dimensions… which is one reason why time is really quite different.
01:21Nevertheless, all together, our four dimensions combine to define the 4D fabric of space-time,
01:28which is ultimately the stage on which all of reality plays out.
01:32At first, it might feel that there's really nowhere else we can go from here.
01:36If reality is four-dimensional, then surely that's just an immovable fact of life.
01:42However, scientists and theorists have long sought to break this most ingrained of systems
01:47by adding in extras.
01:48They've long speculated that the universe is far more complex than we ordinarily observe.
01:54The discovery of even one new dimension would signal a true paradigm shift for our species…
02:00but finding that extra dimension isn't easy.
02:03If it does exist, then it's likely to be buried from view from our perspective, or
02:07else so intricately woven into the fabric of space-time that we might never actually
02:12locate it even if we did come to realise that it was there.
02:16Of course, regardless of the difficulties involved, for those researching extra dimensions,
02:21the supreme dream is usually to uncover a way, any way, to break through to the fabled
02:26other side.
02:27There's a rich history to the field.
02:30Theodor Kaluza, a German mathematician, made arguably the first significant breakthroughs
02:35in 1921.
02:36In short, he proposed to extend the model of general relativity by adding in a fifth
02:42dimension.
02:43By doing so, he believed the fundamental forces of gravity and electromagnetism could be unified.
02:49Kaluza is said to have written to Albert Einstein regarding his ideas, and Einstein
02:54is said to have encouraged him to publish as soon as possible.
02:58Fast forward to today, and perhaps Kaluza's name has been lost to time, but his quest
03:03to unify gravity with the rest of physics is one that is still ongoing.
03:07The search for the famed theory of everything is really what drives today's scientists
03:12to study the possibility of extra dimensions in the first place.
03:16Later on in the 1920s, Oskar Klein expanded on Kaluza's idea, suggesting that the extra
03:22dimension is compactified on such a small scale that it's invisible to us.
03:27According to Klein, it's as though the fifth dimension exists something akin to an incredibly
03:32tight loop within the fabric of spacetime.
03:35Again, it's a loop that's entirely imperceivable to us in the here and now.
03:40The work of both physicists, Theodor Kaluza and Oskar Klein, eventually became known as
03:45the Kaluza-Klein theory.
03:47It laid the groundwork for all later explorations of extra dimensions.
03:51But the path hasn't been easy.
03:53After just a few decades, the Kaluza-Klein theory was largely dropped.
03:57None of its predictions could be experimentally tested, which is something that still dogs
04:02similar models today.
04:03The fact that it's notoriously hard to even devise a way to try to prove that a fifth
04:08dimension is even slightly possible.
04:11That said, there have been other theories that have emerged in the wake of Kaluza-Klein,
04:15and by far the most notable and famous of all is string theory.
04:20During the late 20th century, string theory really shook things up, dramatically expanding
04:25upon all that came before.
04:27The theory posits that the most fundamental particles in the universe are not points,
04:31as was and is traditionally thought, but are tiny, vibrating strings.
04:36It's then the frequency at which these strings vibrate that determine what particles they
04:40are and their fundamental properties.
04:43To a degree, it's like how the frequency of the vibrations of a guitar string is what
04:47determines the note that gets played… only, rather than just music, we're applying the
04:51same thing to how the whole of reality is rendered into being.
04:55Suffice to say, it can be a tricky idea to even contemplate, let alone accept.
05:00Sit for a moment and try to recalibrate everything you see, think, feel… everything you everything…
05:07So that, at its most basic level, it's just endless, wobbly strings.
05:12It's not easy.
05:14The key point, though, is that for string theory to work, advocates calculate that it
05:18requires as many as ten, eleven, or even twenty-six total dimensions.
05:24These extra dimensions are also thought to be compactified, as per the original Kaluza-Klein
05:29theory.
05:30They would need to work at an even smaller scale, though.
05:33Tiny, to us invisible, loops, inside loops, inside loops, and so on.
05:38All to say that the ever-mystical fabric of our reality becomes more and more detailed
05:42and complex, to an almost incomprehensible degree.
05:46For those who support it, string theory is a mathematically elegant idea.
05:51But the problem remains the same.
05:53Testing it in reality is an enormous challenge.
05:56As of now, there's no experimental evidence to confirm string theory.
06:00The extra dimensions are just too unfathomably tiny to get a hold on.
06:04To measure them directly, we'd probably need to be able to track below the Planck
06:09Scale, which is currently completely out of reach, even for our most advanced particle
06:13accelerators.
06:14Therefore, the race is on to detect indirect evidence as a starting point.
06:19Some researchers are keeping their eyes peeled for general gravitational anomalies with this
06:24in mind.
06:25It's thought that if extra dimensions exist, they could, even should, have subtle effects
06:30on the nature of gravity.
06:32For example, one proposal is that gravity might leak into extra dimensions all the time…
06:38which potentially explains why it's by far the weakest of all the fundamental forces
06:42in our reality.
06:43This is one interpretation of what's called the Randall-Sundram model, which, to a point,
06:48ponders whether gravity might become diluted across extra dimensions.
06:52Again, at our current level of technology, we can't yet expect to just discover that
06:57this happens.
06:59Instead, the study of high-energy particle collisions, like at CERN's Large Hadron
07:03Collider, might one day provide indirect evidence from which we can infer the truth.
07:09Interestingly, another route toward proving extra dimensions might also come from, in
07:13many ways, the opposite to sub-Planck length study.
07:17Some are looking to the universe as a whole to provide the answers.
07:20The Cosmic Microwave Background Radiation, or CMBR, is the heat left over from the Big
07:26Bang.
07:27It's everywhere in the universe, and therefore acts as a lens into reality's very earliest
07:32moments.
07:33Theoretically, distortions or unusual patterns within the CMBR could also suggest the influence
07:39of hidden dimensions… although nothing so far has led to this conclusion.
07:44Elsewhere, and there are theories that another potential indicator of extra dimensions might
07:48be carried through space via gravitational waves.
07:52These are ripples in space-time produced by massive cosmic events… but could they also
07:56be influenced by the presence of hidden dimensions?
07:59It's at this stage almost entirely speculation… but the monitoring of gravitational waves
08:04is a relatively new field, and scientists hope that some truly profound answers as to
08:09the true nature of everything could soon be incoming.
08:12So, did scientists already discover an extra dimension?
08:16This could very much be one of those cases when we're just never truly sure of what
08:21it is that we're looking at.
08:22The universe, on both its smallest and largest scales, continually throws up puzzles to solve
08:28and mysteries to decipher.
08:30We famously don't have a theory of everything… which means that there are still huge gaps
08:35in our understanding of how things really work.
08:38For some, those gaps can only be plugged by our realisation that we live in a more-than-4D
08:43world.
08:44And as we continue to test, probe, study and conceptualise the reality around us, it might
08:50be that a fifth dimension, at least, has always been there, holding the worlds together…
08:55but in a way that our eyes simply cannot see.
08:58What do you think?
08:59Is there anything we missed?
09:00Let us know in the comments, check out these other clips from Unveiled, and make sure you
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