Tag: UCL

Yet more of the big question.


I wasn’t going to publish a post for today but then yesterday I read this article on The Conversation and wanted to share it with you. In fact it shares much of what I posted on the 1st, The Big Question. Because time and infinity are beautifully connected.


What is time – and why does it move forward?

By Thomas Kitching, Lecturer in Astrophysics, UCL

Imagine time running backwards. People would grow younger instead of older and, after a long life of gradual rejuvenation – unlearning everything they know – they would end as a twinkle in their parents’ eyes. That’s time as represented in a novel by science fiction writer Philip K Dick but, surprisingly, time’s direction is also an issue that cosmologists are grappling with.

While we take for granted that time has a given direction, physicists don’t: most natural laws are “time reversible” which means they would work just as well if time was defined as running backwards. So why does time always move forward? And will it always do so?

Does time have a beginning?

Any universal concept of time must ultimately be based on the evolution of the cosmos itself. When you look up at the universe you’re seeing events that happened in the past – it takes light time to reach us. In fact, even the simplest observation can help us understand cosmological time: for example the fact that the night sky is dark. If the universe had an infinite past and was infinite in extent, the night sky would be completely bright – filled with the light from an infinite number of stars in a cosmos that had always existed.

For a long time scientists, including Albert Einstein, thought that the universe was static and infinite. Observations have since shown that it is in fact expanding, and at an accelerating rate. This means that it must have originated from a more compact state that we call the Big Bang, implying that time does have a beginning. In fact, if we look for light that is old enough we can even see the relic radiation from Big Bang – the cosmic microwave background. Realising this was a first step in determining the age of the universe (see below).

But there is a snag, Einstein’s special theory of relativity, shows that time is … relative: the faster you move relative to me, the slower time will pass for you relative to my perception of time. So in our universe of expanding galaxies, spinning stars and swirling planets, experiences of time vary: everything’s past, present and future is relative. 

So is there a universal time that we could all agree on?

The universe’s timeline. Design Alex Mittelmann, Coldcreation/wikimedia, CC BY-SA

It turns out that because the universe is on average the same everywhere, and on average looks the same in every direction, there does exist a “cosmic time”. To measure it, all we have to do is measure the properties of the cosmic microwave background. Cosmologists have used this to determine the age of the universe; its cosmic age. It turns out that the universe is 13.799 billion years old. 

Time’s arrow

So we know time most likely started during the Big Bang. But there is one nagging question that remains: what exactly is time? 

To unpack this question, we have to look at the basic properties of space and time. In the dimension of space, you can move forwards and backwards; commuters experience this everyday. But time is different, it has a direction, you always move forward, never in reverse. So why is the dimension of time irreversible? This is one of the major unsolved problems in physics. 

To explain why time itself is irreversible, we need to find processes in nature that are also irreversible. One of the few such concepts in physics (and life!) is that things tend to become less “tidy” as time passes. We describe this using a physical property called entropy that encodes how ordered something is.

Imagine a box of gas in which all the particles were initially placed in one corner (an ordered state). Over time they would naturally seek to fill the entire box (a disordered state) – and to put the particles back into an ordered state would require energy. This is irreversible. It’s like cracking an egg to make an omelette – once it spreads out and fills the frying pan, it will never go back to being egg-shaped. It’s the same with the universe: as it evolves, the overall entropy increases.

Unfortunately that’s not going to clean up itself. Alex Dinovitser/wikimediaCC BY-SA

It turns out entropy is a pretty good way to explain time’s arrow. And while it may seem like the universe is becoming more ordered rather than less – going from a wild sea of relatively uniformly spread out hot gas in its early stages to stars, planets, humans and articles about time – it’s nevertheless possible that it is increasing in disorder. That’s because the gravity associated with large masses may be pulling matter into seemingly ordered states – with the increase in disorder that we think must have taken place being somehow hidden away in the gravitational fields. So disorder could be increasing even though we don’t see it.

But given nature’s tendency to prefer disorder, why did the universe start off in such an ordered state in the first place? This is still considered a mystery. Some researchers argue that the Big Bang may not even have been the beginning, there may in fact be “parallel universes” where time runs in different directions

Will time end?

Time had a beginning but whether it will have an end depends on the nature of the dark energy that is causing it to expand at an accelerating rate. The rate of this expansion may eventually tear the universe apart, forcing it to end in a Big Rip; alternatively dark energy may decay, reversing the Big Bang and ending the Universe in a Big Crunch; or the Universe may simply expand forever.

But would any of these future scenarios end time? Well, according to the strange rules of quantum mechanics, tiny random particles can momentarily pop out of a vacuum – something seen constantly in particle physics experiments. Some have argued that dark energy could cause such “quantum fluctuations” giving rise to a new Big Bang, ending our time line and starting a new one. While this is extremely speculative and highly unlikely, what we do know is that only when we understand dark energy will we know the fate of the universe.

So what is the most likely outcome? Only time will tell.


Let me explain, in part, entropy. Because while I and many others sort of understand it, the principle behind entropy is much more detailed.

It is explained pretty well on WikiPedia, from which I reproduce the first paragraph.

Entropy is a scientific concept, as well as a measurable physical property that is most commonly associated with a state of disorder, randomness, or uncertainty. The term and the concept are used in diverse fields, from classical thermodynamics, where it was first recognized, to the microscopic description of nature in statistical physics, and to the principles of information theory. It has found far-ranging applications in chemistry and physics, in biological systems and their relation to life, in cosmologyeconomicssociologyweather scienceclimate change, and information systems including the transmission of information in telecommunication.[1]

There’s a little bit more to read … 😉

Again, I am going to finish with sharing that image from Unsplash.

Imagine the universe is constant whichever direction one looks in, to 1 in 10,000. That is truly amazing!

Optimistically unrealistic!

A reflection of our unconscious minds – and the potential perils ahead.

Last Monday, March 12th, the BBC aired a programme under their excellent Horizon science series.  This programme was entitled, Out of Control?  Here’s how the programme was introduced,

We all like to think we are in control of our lives – of what we feel and what we think. But scientists are now discovering this is often simply an illusion.

Surprising experiments are revealing that what you think you do and what you actually do can be very different. Your unconscious mind is often calling the shots, influencing the decisions you make, from what you eat to who you fall in love with. If you think you are really in control of your life, you may have to think again.

The whole 60 minute programme was fascinating right from the start when Professor Nobre introduced the secret world of our unconscious mind.  Professor Anna Nobre heads The Brain & Cognition Laboratory, a cognitive neuroscience research group at the Department of Experimental Psychology in the University of Oxford.

For starters, how much of your mind do you think is your conscious mind as opposed to your unconscious mind?  Watch this clip and be amazed!

“Are you in control of your unconscious, or is it in control of you?”

So let me link how our mind works to something more relevant today than possibly any other aspect of life.

I’m thinking of the fundamental question that bothers me and, perhaps millions of others.  That question being: “Why, with the overwhelming scientific evidence that man is critically threatening the planet’s biosphere upon which we all depend, is there not an equally overwhelming global commitment for change to a sustainable way of life?

Take, for example, this compelling story.

Last Saturday the BBC News website published a report by Richard Black, the BBC’s Environment correspondent, that opened thus,

An eminent UK engineer is suggesting building cloud-whitening towers in the Faroe Islands as a “technical fix” for warming across the Arctic.

Scientists told UK MPs this week that the possibility of a major methane release triggered by melting Arctic ice constitutes a “planetary emergency“. [my emboldening]

The Arctic could be sea-ice free each September within a few years.

and later goes into this detail (do please read it all, it’s only a few minutes of quiet reading),

On melting ice

The area of Arctic Ocean covered by ice each summer has declined significantly over the last few decades as air and sea temperatures have risen.

For each of the last four years, the September minimum has seen about two-thirds of the average cover for the years 1979-2000, which is used a baseline. The extent covered at other times of the year has also been shrinking.

What more concerns some scientists is the falling volume of ice.

Analysis from the University of Washington, in Seattle, using ice thickness data from submarines and satellites, suggests that Septembers could be ice-free within just a few years.

Data for September suggests the Arctic Ocean could be free of sea ice in a few years

“In 2007, the water [off northern Siberia] warmed up to about 5C (41F) in summer, and this extends down to the sea bed, melting the offshore permafrost,” said Peter Wadhams, professor of ocean physics at Cambridge University.

Among the issues this raises is whether the ice-free conditions will quicken release of methane currently trapped in the sea bed, especially in the shallow waters along the northern coast of Siberia, Canada and Alaska.

Methane is a much more potent greenhouse gas than carbon dioxide, though it does not last as long in the atmosphere.

Several teams of scientists trying to measure how much methane is actually being released have reported seeing vast bubbles coming up through the water – although analysing how much this matters is complicated by the absence of similar measurements from previous decades.

Nevertheless, Prof Wadhams told MPs, the release could be expected to get stronger over time.  “With ‘business-as-usual’ greenhouse gas emissions, we might have warming of 9-10C in the Arctic.  That will cement in place the ice-free nature of the Arctic Ocean – it will release methane from offshore, and a lot of the methane on land as well.”

This would – in turn – exacerbate warming, across the Arctic and the rest of the world.

Abrupt methane releases from frozen regions may have played a major role in two events, 55 and 251 million years ago, that extinguished much of the life then on Earth.

Meteorologist Lord (Julian) Hunt, who chaired the meeting of the All Party Parliamentary Group on Climate Change, clarified that an abrupt methane release from the current warming was not inevitable, describing that as “an issue for scientific debate”.

But he also said that some in the scientific community had been reluctant to discuss the possibility.

“There is quite a lot of suppression and non-discussion of issues that are difficult, and one of those is in fact methane,” he said, recalling a reluctance on the part of at least one senior scientists involved in the Arctic Climate Impact Assessment to discuss the impact that a methane release might have.

Reams of other factual evidence shows that mankind may have only a few years left to stop the planet going into a runaway condition that would then extinguish much of the life on Earth!

So what’s stopping us?

Dr. Sharot

Well back to that Horizon programme.  In the programme, Dr. Tali Sharot of University College London explains how we are all optimists despite the risks.  I.e. our unconscious mind deliberately prevents negative information from affecting our conscious mind, our conscious judgment.

In an experiment, an individual is asked to guess the likelihood of a whole range of outcomes, 80 in all.  Ergo, you see a gentleman guessing the likelihood of cancer as 18%, of a bone fracture as 10%, of Alzheimer’s as 2%, and so on.

In some cases he guessed a pessimistic probability, in others an optimistic probability.  After each guess he was shown the correct probability.  E.g. cancer 30% vs his estimate of 18%, for a bone fracture 34% vs his guess of 10%, and the risk in reality of Alzheimer’s is 10% versus his instinct of just 2%.   I’ve just quoted his optimistic guesses, in many questions his guess was a pessimistic view, i.e. he guessed a higher likelihood than the statistical reality.

Then he was asked all 80 questions again, having seen the accurate probability compared to his intuitive guess.

So here’s the fascinating outcome.

Where his instinct was a negative guess versus the statistical probability then he adjusted his mind and was able to quote a more accurate figure the second time around.  But where the reality was more pessimistic than his first guess, then that adjusted knowledge wasn’t retained.  In other words, our beliefs only change when we can adjust to a more positive view of the future.

I just hope I have made that clear.  Readers may like to view an article written by Dr. Sharot published in TIME Magazine in May, 2011, called The Optimism Bias or read the introduction to a lecture given in Seattle in June, 2011;  “A sunny outlook doesn’t just make you a more pleasant companion: Tali Sharot argues that optimism is a tool for survival and happiness that gets us through hard times—even an economic recession. Sharot, author of The Optimism Bias, uncovers myths about optimism, illuminates the ways it can affect our lives, examines why optimism is necessary for us to function, and illustrates how the human brain is extremely adept at turning lead into gold.

A summary of a publication, Sharot, T. (2011). The optimism bias. Curr Biol 21(23), R941-R945, reads,

The ability to anticipate is a hallmark of cognition. Inferences about what will occur in the future are critical to decision making, enabling us to prepare our actions so as to avoid harm and gain reward. Given the importance of these future projections, one might expect the brain to possess accurate, unbiased foresight. Humans, however, exhibit a pervasive and surprising bias: when it comes to predicting what will happen to us tomorrow, next week, or fifty years from now, we overestimate the likelihood of positive events, and underestimate the likelihood of negative events. For example, we underrate our chances of getting divorced, being in a car accident, or suffering from cancer. We also expect to live longer than objective measures would warrant, overestimate our success in the job market, and believe that our children will be especially talented. This phenomenon is known as the optimism bias, and it is one of the most consistent, prevalent, and robust biases documented in psychology and behavioral economics.

More fascinating information can be found at the Affective Brain Lab.

So here’s the crunch!

Our bias towards an optimistic future is a “tool for survival and happiness that gets us through hard times.”  But if that ancient bias is preventing mankind from recognising just how close we may be to some form of ‘tipping point’ then this tool for survival may be our undoing.

But if on the other hand, we now unite in changing our ways, first by community then by town then by country our future is incredibly optimistic.

 “A single candle may light a thousand others and they in turn many thousands more” – Buddha