Up to now, humans have only been able to observe four dimensions in the universe – height, length, width and time.
But beyond these dimensions, collectively known as ‘spacetime’, there may be more that we cannot perceive – including the fabled fifth dimension.
In an episode of ‘The Twilight Zone’, the fifth dimension is depicted as a terrifying, warped place where our sense of time and direction is greatly distorted.
It later inspired an episode of The Simpsons, where Homer accidentally enters another dimension when he hides behind a bookcase to escape his sisters-in-law.
But Christopher Nolan‘s 2014 film ‘Interstellar’ presents a more compelling version, where people can perceive and interact with all moments of time – past, present and future – in multiple possible timelines that exist in parallel.
‘It would be like being able to go into an infinity of worlds like the one that we live in,’ Michael Pravica, a professor of physics at the University of Nevada, told MailOnline.
But what evidence is there in the universe to suggest the concept is more than just Hollywood-worthy sci-fi?
Now, scientists reveal the clues that at least one other dimension does exist.
In an episode of The Simpsons, Homer accidentally enters the third dimension when he hides behind a bookcase to escape his sisters-in-law. The joke was that the third dimension had not existed in the show until then as the characters had always been drawn in two dimensions (height and length)

In a 1962 episode of ‘The Twilight Zone’ called ‘Little Lost Girl’, a six-year-old passes into another dimension from her bedroom
HUMAN CONCIOUSNESS
A belief that the universe is made up of more dimensions than just the four we perceive – height, length width and time – is known as ‘hyperdimensionality’.
Professor Pravica, who received a PhD in condensed matter physics from Harvard University, points to human consciousness as evidence of hyperdimensionality.
When we dream, meditate or use our brains for creative or intellectual tasks (such as making art or pondering philosophy), our consciousness taps into a higher dimension, he claims.
In these moments, our consciousness syncs with hidden dimensions and receives a flood of inspiration, according to the academic.
In other words, the ability to be fully conscious is to enter a dimension that is not accounted for by the existing four dimension (height, length, width and time).
Humans are the only species that can reach this sort of full consciousness, while some organisms on this planet don’t have consciousness at all.
‘Humans are actually higher dimensional creatures from the standpoint of the soul which is the essence of our consciousness and conscience,’ Professor Pravica told MailOnline.

In Christopher Nolan’s 2014 film ‘Interstellar’, the fifth dimension lets people perceive and interact with all moments of time – past, present and future – in multiple possible timelines that exist in parallel

When we dream, meditate or use our brains for creative or intellectual tasks (such as making art or pondering philosophy), our consciousness taps into a higher dimension, the theory claims
However, this theory is controversial; Stephen Holler, associate professor of physics at Fordham University, has said it ‘borders on science fiction‘.
Howard Wiseman, a physicist at Griffith University in Australia, said consciousness is ‘considered a mystery by a fair fraction of scientists and philosophers’.
‘But very few of them would say that mystery points to extra dimensions in that sense,’ Professor Wiseman told MailOnline.
LIMITS OF THE UNIVERSE
It was more than a century ago that Russian physicist Alexander Friedmann provided evidence that our four-dimensional universe is constantly expanding.
This generally-accepted concept is central to the Big Bang theory – that the universe exploded into existence from a single minute point about 14 billion years ago and has been expanding since.
Now, this mind-bogglingly vast space that we call the universe is 93 billion light years in diameter – and expands another light year for every Earth year.
Although we don’t know what’s beyond the universe, the fact it can keep growing suggests the possibility of higher-dimensional planes beyond, according to Professor Pravica.

The theory of general relativity allows for the universe to take one of three forms – spherical, flat like a sheet of paper or or open like a saddle (‘hyperbolic’)

The universe’s size is unknown, and it may or may not be infinite in extent – but there is always a limit in how much humanity is able to observe (‘the observable universe’). This illustration marks the observable universe – with the circular edge its limit and our galaxy, the Milky Way, in the centre
What’s more, cosmologists speculate that the universe is not perfectly flat, meaning it must be at least slightly ‘hyperbolic’ (shaped like a saddle) or spherical.
‘By definition, this implies that there are higher dimensions to curve into,’ said Professor Pravica.
GRAVITY
According to the Standard Model of particle physics, there are four fundamental forces of nature – electromagnetism, the strong nuclear force, the weak nuclear force and gravity.
Curiously, gravity is so much weaker than the other fundamental forces – a fact that’s evidenced in everyday life.
For example, a small fridge magnet is enough to create an electromagnetic force greater than the gravitational pull exerted by our planet – otherwise the magnet would fall onto the floor.
We don’t feel the full effect of gravity because part of it potentially spreads to extra dimensions, according to the European Organization for Nuclear Research (CERN).
If extra dimensions exist, they could explain why the universe is expanding faster than expected and why gravity is weaker than the other forces of nature.

In Einstein’s view of the world, gravity is the curvature of spacetime. Depicted here are merging neutron stars, a source of gravitational waves, which are ripples in space-time caused by some of the most violent and energetic processes in the universe
Also, unknown dimensions could cause ripples through reality by modifying gravitational waves – changes in the spacetime fabric.
STRING THEORY
Lastly, an idea that the universe may contain many more dimensions that we cannot yet observe is supported by something called ‘string theory’.
In string theory, reality is not made up of elementary particles (like electrons or quarks) as previously thought, but infinitely small vibrating one-dimensional strings.
String theory unifies the two pillars of modern physics – quantum mechanics (the physics of the very small) and general relativity (the physics of the very big).
In this sense, string theory provides a compelling answer of how the universe works, albeit by reimagining the fundamentals of reality.
But according to physicists, for string theory to work it necessitates multiple dimensions to exist – as many as 10 or 11 dimensions in fact.
‘String theory postulates that there are higher dimensions, some which wrap around each other and cannot be observed as they are too small,’ Professor Pravica told MailOnline.
‘The problem is that string theory is not verifiable at the present time, experimentally.’