The Mysterious Arrow of Time

Wave your hand from left to right and observe the movement. What you are witnessing is movement, or motion through space. This may seem extremely obvious to you but the significance is vital. If we are able to observe these dimensions, why can’t we observe the 4th dimension, time? You may think of a clock as the symbol of time, but if a clock stops ticking, time doesn’t stop, only motion. Also, like our hand that was just moving forwards and backwards through space, can we move forwards and backwards through time? Of course not, we are all fully aware that time has only one direction; it has always flown from past to future and always will.

The strange thing is, in the laws of physics there appears to be no ‘arrow’ of time. If you apply Newton’s laws of motion to calculate where a ball will land in the future, you can just as well work out where it was thrown from in the past. So where does this mysterious arrow of time emerge from? Could it have formed by human perception? A result of our brains attempt to arrange events that happen around us? With this viewpoint, time is merely an emergent concept of motion because it becomes evident through motion and is measured by comparison with other motions such as sunrise/sunsets, night and day, the changing seasons, the aging process, etc.

A clue of where this arrow originates from is in a concept known as entropy. In a nutshell, entropy is a measure of how orderly things are and is a value assigned to any macroscopic system. It reflects the number of times a system’s particles can be rearranged without altering its overall appearance. For example, a pond of water would be a high entropy system because the water molecules can be arranged in a number of ways. On the other hand, an ice crystal would be a low entropy system due to the precision of arrangement. According to the second law of thermodynamics, high entropy states are more likely than low entropy states; therefore things will become more disorderly because there are more ways to produce them. So, if you neatly stack papers on your desk, and you walk away, you’re not surprised if they turn into a mess. However, you’d be very surprised if you walked away from a mess of papers and return to them neatly stacked. That’s entropy and the arrow of time.

However, the second law of thermodynamics doesn’t necessarily include time; it focuses on particle arrangement only. The only way to explain the arrow of time is to assume the universe started off at an incredibly low entropy state. “Time’s arrow depends on the fact that the universe started up in a very peculiar state,” says physicist Carlo Rovelli of the Center for Theoretical Physics in Marseilles, France. “Had it started up in a random state, there would be nothing to distinguish the future from the past”.

Radiation from the big bang is evidence for this theory by providing us with a snapshot of the infant universe. It shows that at the beginning, matter and radiation were spread extremely smoothly throughout the universe. You would think it was a high entropy state but when you take gravity into account, entropy changes. Gravity always tries to group matter together so in a system governed by gravity, a black hole is a far more likely state than a smooth distribution. Due to gravity, this low entropy smoothness is remarkably unlikely but cosmologists do have an explanation for this rare state. At the first fraction of a second after the big bang, there was a rapid burst of expansion known as inflation. It was inflation that resulted in this unnatural smoothness by ironing out all the creases. However, in order for inflation to occur, the inflaton field which drove this expansion from 10−35 to 10−34 seconds post-big bang, must have some incredible properties. To make the matter all the more confusing, the inflaton field has low entropy itself.

A possible explanation is that inflation didn’t happen at once. You could picture the inflaton field as a high entropy state with varying and random properties. In this case, the low entropy inflaton that gave rise to our smooth universe (and therefore our arrow of time) could just be an anomaly in the larger high entropy field. So it was down to chance. The physics of the inflaton field shows that there is enough of it to give rise to more universes, leading on to the multiverse theory. Is our universe part of a vast multiverse due to this inflaton field? The theory seems justifiable and could lead on to predict some universes having an arrow of time while others don’t.

So what viewpoint will you support on the explanation of time, psychological or scientific? If you are edging towards the psychological viewpoint, that the arrow of time is merely psychological and in reality, there is no such thing, you’re implying that the past, present and future are all happening at once. In that case, at this moment in ‘time’, a part of your mind knows what will happen in the future but due to our brain’s evolution and our perception, we don’t recognize this ability… Now that’s something to think about. Quite possibly all will be revealed in the future – that is if there is such a thing.

Source: NewScientist: Special Issue, ‘Time The Most Mysterious Dimension of All’ pp 37-53, October 8th 2011

(Huge round of applause especially to Amanda Gefter and her brilliant article!)

Through the Looking Glass

 

If someone unfortunately fell into a black hole, would they be stretched and crushed by its immense gravity, as most physicists believe, or would they be propelled into a parallel universe and emerge in another time era? To solve this complex question, physicists are beginning to explore one of the most intriguing and bizarre chapters of modern physics.

wormhole

Imagine the universe being a basketball and the surface representing 3D space. Point A on the ball is where you are and point B on the other side is your desired destination.  By travelling across the surface, you’d have to cover a great distance. So stop for a moment and contemplate a shortcut from point A to point B…

Did you think of a potential tunnel going through the basketball?

If you did, you’re thinking of a worm hole. The theoretical possibility that there are 4D hyperspace ‘tunnels’ in the universe with black holes as the entrance and white holes as their exits. They are a valid consequence of Einstein’s theory of general relativity and therefore plausible in calculations. Black holes are exceedingly dense and bent regions of space time where nothing can escape beyond the event horizon; not even light, hence its name. These white holes are similar to worm holes in the sense that they have not been observed and are highly applauded by sci-fi writers and theoretical physicists.  The object which travels through the worm hole and out of the white hole will appear not just anywhere in space, but anywhere in time too.  Also, it is important to note that the universe doesn’t have to be circular to sustain the existence of worm holes. It is just easier to picture the situation this way, in theory the universe could be bent, flat or any shape.

Suddenly your mere journey to school or work seems a lot less significant in comparison to the prospect of zooming from universe to universe or even backwards or forwards in time. I wouldn’t blame you if your sceptical, but the idea of time travel is feasible. Russian cosmonaut, Sergei Avdeyev, holds the current  record for time dilation experienced by human, 0.02 seconds. Also, communication and other satellites are continuously travelling through time and need specific circuits to calibrate their time to earth time. However, the design of worm holes has several loop holes. Firstly, they are indistinguishable. That being said, the black hole in the centre of the milky way, Sagittarius A*, could in theory be a worm hole. Studying the matter falling in would allow us to differentiate between them. As worm holes don’t have an event horizon, x-rays produced by discs of hot matter would be seen whereas they would completely disappear in black holes. Currently, we don’t have the technology to be able to detect wormholes, an example of where equipment begins to limit modern era’s knowledge.

Presently, there are wormholes all around us but on a scale too minute to see. If we could grab hold of one and expand its mouth for an object to enter, we’d be making notable progress. In 1996, a sub microscopic wormhole was shown to have a throat radius of no more than 10-32meter, only slightly larger than the Plank length 10-35 meter, the smallest distance with a definite meaning. As wormholes are highly unstable, a dilemma rises. They will collapse before anything will have the chance to travel through because behind the design of a wormhole, space time is oddly warped and as this is not natural, it wants to return to being flat as quickly as possible.  As matter bends space time inwards, creating gravity, it possesses positive energy density. On the other hand, ‘exotic matter’ has negative energy density thus repels gravity. Its ability to repel gravity implies that it can be used to stabilize a wormhole. But where will we generate this exotic matter from? The closest known way to produce exotic matter is via the Casmir effect, the density between two uncharged metal plates facing each other in a vacuum. This exotic matter has to be used in the form of extremely thin bands around the throat of the wormhole. But once the wormhole opens, radiation entering it will accelerate to lightning speeds due to its gravity and this will cause it to collapse quicker.

Another idea is to manually make a wormhole. You could fire beams of electrons in one direction, and beams of positrons in the opposite direction so they encircle an asteroid belt millions of miles long. To ensure they follow a circular path, electromagnets would need to be used to bend the particles as they zoom around the belt. Eventually when an electron and positron collide at such extreme speeds, they will annihilate, the energy produced should in theory be powerful enough to create a small rip in the fabric of space time. The next step would be to insert negative matter into its aperture. The probability of this idea being successful is very low, and it would require exceedingly advanced technology.

So how do we sustain a wormhole? Well, in a black hole, the laws of physics do not apply once past the event horizon. In other words, the theory of general relativity which looks at the cosmos or quantum physics which focuses on the microscopic doesn’t have to be used when discussing wormholes. Instead, there needs to be a “theory of everything” and the closest we have to that is string theory.

Now, picture a secluded 2D world, where only length and width is feasible. If it started raining on a lake, people would take notice of the ripples in the water, or the height, the third dimension. They wouldn’t understand where it is coming from though and how it is there, much like the distressed state we 3Ders are in when we sit to contemplate the presence and origin of light. According to string theory, “light” is nothing but vibrations rippling along the 5th dimension and the universe is a symphony of vibrating strings. By adding higher dimensions, we can easily accommodate more of the fundamental forces, including the strong and weak nuclear forces. Physicists believe that at the Big Bang, the universe was fully 10 dimensional, which includes all four fundamental forces. Only after the instant of creation did 6 of the 10 dimensions “curled up” into a ball too tiny to observe. When space time has more than 4 dimensions, the theorems that forbid the existence of a wormhole without negative energy may not apply.

It comes without a surprise that the mathematics behind the 10th dimensional string theory is beautifully intricate and supports the existence of a wormhole more readily. But don’t pack your bags quite yet, just because wormholes are possible doesn’t necessarily mean they exist. They could just be mathematical remainders of general relativity. Also, don’t expect finding a convenient key to open up a wormhole in your garden for a quick peep at this weeks euro million lottery numbers. Nevertheless, it has potential for being possibly but the entire idea of wormholes are still profoundly elusive and will require years of research and engineering before joining Alice on her adventures through the mysterious wonderland above our heads.

-Rosie

Source: http://mkaku.org/home/?page_id=423

What came first, the chicken’s DNA or chicken’s protein?

If you metaphorically prepare a solution from the ‘what came first, the chicken or the egg?’ paradox to add to a crucible, it would almost immediately set light to an inferno of topical debate. However, the mother of these paradoxical conundrums- what came first DNA or protein, prompts the debate up to a whole new energy level.

DNA stores the instructions to carry out the task of creating proteins, therefore without DNA there wouldn’t be any proteins, thus no life. But enzymes (proteins) are necessary in the process of DNA replication. Without one, the other wouldn’t exist. So if we rewind to 4.6 billion years ago, when the earth was a boiling ocean of molten rock and breathing suffocating fumes, when the first cells eventually appeared- what molecule started it all?

The answer could potentially lie in the analysis of DNA’s sister, RNA. DNA and RNA are very similar molecules, their few differentiating properties is the fact that DNA is a double stranded molecule whereas RNA is single stranded, therefore smaller. Logically, this should lead you to think that if RNA is smaller; shouldn’t it have been present first in order to build up to form DNA? Imagine RNA as the code (e.g. 1=A, 2=B, 3=C, 4=D, etc) needed to translate the DNA information so can be read (e.g. 8,5,12,12,15 is read as ‘hello’ but we wouldn’t have known without RNA). Therefore, without RNA, reading DNA is incomprehensible, highlighting the point that one cannot do its job without the other.

The discovery in the 1960s that RNA had the ability to fold like a protein invoked tantalizing hints that an answer was soon to be reached. If RNA could fold like a protein, it could mimic enzyme activity and catalyze reactions as well as storing information like it originally does. In theory, some RNA molecules may be capable of making more RNA molecules without the need of proteins. Like everything seems to be at the time, it sounded like an absurd idea until 1982 when Thomas Cech finally found the long sought after multitasking RNA enzyme, ribozyme. It was found in a peculiar unicellular animal occurring in seven sexes, tetrahymena thermophila-no wonder it took 22 years to find!

Cech’s discovery unlocked many doors in the advancement of ribozyme and similar research. People started discovering more ribozymes present in living organisms and analysed them in labs to find that this short section of RNA is able to cut itself out of a longer chain. If you reverse the reaction, the short sections would arrange themselves in an altered format. This goes on to support Darwin’s Theory of Evolution as it could significantly accelerate evolution. Although RNA is less stable and isn’t as competent as storing information as DNA and isn’t as versatile as proteins, why focus on the pessimistic side when the miniature yet impressive ribozyme has been hidden in the dark, killing two birds with one stone ? The achievement of uncovering ribozyme promotes the hypothesis of “the RNA world” that the first life consisted of RNA molecules that catalyzed the production of further RNA molecules.

Without a surprise, there are hundreds of questions which continue to linger in response the provisional answer of ‘ribozyme’ of this article. Where did the energy to drive this activity come from? What was the first life like? So where did these enigmatic molecules arise from? The probability that DNA or RNA randomly and spontaneously assembled in perfect synch into their correct forms whilst being completely independent from one another in the same time and place in the universe is statistically inconceivable. As we are not aware of any fossilized vestiges of the first replicators, we are left to independently contemplate whether there was intervention from an ‘intelligence’ to guide the information (DNA) and the code (RNA) to work together to form the life we witness today. We may never know for certain, but scientists are definitely exploring these encouraging pathways in attempt to explain the unexplainable. Who knows, we may just be living in an RNA world after all.

(Ref: New Scientist, August 13th 2011)

To be or not to be a doctor, that is the question.

Now that a new series of Junior Doctors has started on TV, I cannot help but to imagine myself in their positions. Realistically, that will happen in less than a decade; just the thought brings a whirl of feelings. An instant rush of exhilaration, anticipation and truthfully, elements of trepidation. But the feeling that dominates all is of passion.

Through the work experience I have been fortunate to acquire, I now realize the demands of becoming a doctor. It isn’t a mere 9-5 job where you can skip merrily home when the clock strikes 5 and I am fully aware that becoming a doctor doesn’t involve floating down a sterile hall of a prestigious hospital, with the iconic stethoscope around the neck and clothed in celestial white coats. Reality is, it involves prolonged hours of ‘work’, 110% commitment towards patients, flexibility, persistence and an unwaveringly strong will power.

You may be wondering, why I added single inverted commas around the term, work? It is because I resolutely believe that medicine isn’t as simple as being just ‘work’, it is a choice in lifestyle.At the Medlink conference 2011, my initial thoughts on the medical field were strengthened as I listened to several experienced individuals’ stories in the health sector.

In my 16 years of living I have witnessed enough suffering in the world to remember for the rest of my life. The reason I am committed to travel this understandably toilsome journey is for a very simple reason. So simple that it only takes 17 muscles to achieve. All I want is to impact someone’s life in such a way that they will smile. Not the habitual smile they’ve become accustomed to in everyday use. But a bona fide smile. I want to be able to truly feel the impact I have made radiate off them with an unrecognizable frequency. I want to relight the spark that used to shine in their eyes and know a cumbersome weight has been lifted off their shoulders. Knowing that I’ve had this impact or even a degree of this impact on someone is genuinely indescribable. So much so that it’s overwhelming enough to eradicate any initial trepidation I had in my thoughts for the future. Whatever happens to me in my life, whatever challenges I am faced with, if there’s one thing I’m certain of in this world, I am determined I will become a doctor.

Until next time,

Rosie Bhogal :)