"Why does time go forwards, not backwards?" by Martha Henriques for BBC Future

I've been meaning to share this fascinating article from BBC Future for a little while now. I am a bit of armchair physicist so this is really interesting to me. And as we have seen, modern physics also incorporates philosophy and spirituality to varying degrees, areas that I am also interested in.

Why does time go forwards, not backwards?

By Martha Henriques
3rd October 2022

The arrow of time began its journey at the Big Bang, and when the Universe eventually dies there will be no more future and no past. In the meantime, what is it that drives time ever onward?

When Isaac Newton published his famous Principia in 1687, his three elegant laws of motion solved a lot of problems. Without them, we couldn't have landed people on the Moon 282 years later. But these laws brought to physics a new problem, which wasn't fully appreciated until centuries after Newton and still nags at cosmologists today.

The issue is that Newton's laws work about twice as well as we might expect them to. They describe the world we move through every day – the world of people, the hands that move around a clock and even the apocryphal fall of certain apples – but they also account perfectly well for a world in which people walk backwards, clocks tick back afternoon to morning, and fruit soars up from the ground to its tree-branch.

"The interesting feature of Newton's laws, which wasn't appreciated till much later, is that they don't distinguish between the past and the future," says the theoretical physicist and philosopher Sean Carroll, who discusses the nature of time in his latest book The Biggest Ideas in the Universe. "But the directionality to time is its most obvious feature, right? I have photographs of the past, I don't have any photographs of the future."

The problem is not confined to the centuries-old theories of Newton. Virtually all of the cornerstone theories of physics since then have worked just as well going forward in time as they do backwards, says physicist Carlo Rovelli of the Centre for Theoretical Physics in Marseille, France, and the author of books including The Order of Time.

"Starting from Newton, and then Maxwell's theory of electromagnetism, then Einstein's work, and then quantum mechanics, quantum field theory, general relativity, and even quantum gravity – there is no distinction between past and future," Rovelli says. "Which came as a surprise, because the distinction is so evident to all of us. If you make a movie, it's obvious which way is the future and which one is the past."

How does a clear direction of time emerge from these descriptions of the Universe, which all lack their own arrow of time? As Marina Cortês, an astrophysicist at the University of Lisbon, puts it: "There's a lot of implications that start with taking seriously the question, 'Why does time pass?'"

Part of the answer lies at the Big Bang nearly 14 billion years ago. Another insight comes from the opposite extreme, in the Universe's eventual death.

But before embarking on this epic journey back and forth along the timeline of the Universe, it's worth stopping off in 1865, just as the first truly time-directional law of physics came hurtling down the tracks of the Industrial Revolution.

GATHERING STEAM

In the 19th Century, when coal was shovelled into furnaces to generate steam power, scientists and engineers hoping to develop better engines embraced a set of principles that described the relationship between heat, energy and motion. They became known as the laws of thermodynamics.

In Germany, 1865, the physicist Rudolf Clausius stated that heat cannot pass from a cold body to a hot one, if nothing else around them changes. Clausius came up with the concept he called "entropy" to measure this behaviour of heat – another way of saying heat never flows from a cold body to a hot one is to say "entropy only ever increases, never decreases."

As Rovelli stresses in The Order of Time, this is the only basic law of physics that can tell apart the past from the future. A ball can roll down a hill or be kicked back to its summit, but heat can't flow from cold to hot.

To illustrate, Rovelli picks up his pen and drops it from one hand to the other. "The reason this stops in my hand is that it has some energy, and then the energy is turned into heat and it warms up my hand. And the friction stops the bouncing. Otherwise, if there was no heat, this would bounce forever, and I would not distinguish the past from the future."

So far, so straightforward. That is, until you start to consider what heat is on a molecular level. The difference between hot things and cold things is how agitated their molecules are – in a hot steam engine, water molecules are very excited, careening around and colliding into each other rapidly. The very same water molecules are less agitated when they coalesce as condensation on a windowpane.

Here's the problem: when you zoom in to the level of, say, one water molecule colliding and bouncing off another, the arrow of time disappears. If you watched a microscopic video of that collision and then you rewound it, it wouldn’t be obvious which way was forwards and which backwards. At the very smallest scale, the phenomenon that produces heat – collisions of molecules – is time-symmetric.

This means that the arrow of time from past to future only emerges when you take a step back from the microscopic world to the macroscopic – something first appreciated by the Austrian physicist-philosopher Ludwig Boltzmann.

"So the direction of time comes from the fact that we look at big things, we don't look at the details," says Rovelli. "From this step, from the fundamental microscopic vision of the world to the coarse-grained, the approximate description of the macroscopic world – this is where the direction of time comes in.

"It's not that the world is fundamentally oriented in space and time," Rovelli says. It's that when we look around, we see a direction in which medium-sized, everyday things have more entropy – the ripened apple fallen from the tree, the shuffled pack of cards.

While entropy does seem to be inextricably bound up with the arrow of time, it feels a bit surprising – perhaps even disconcerting – that the one law of physics that has a strong directionality of time built into it loses this directionality when you look at very small things.

"What is entropy?" Rovelli says. "Entropy is simply how much we're forgetting about the microphysics, how much we are forgetting about the molecules."

THE BEGINNING AND THE END

If there is an arrow of time, where did it come from in the first place?

"The answer is embedded in the beginning of the Universe," says Carroll. "The answer is because the Big Bang had low entropy. And still, 14 billion years later we are swimming in the aftermath of that tsunami that started near the Big Bang. That's why time has a direction for us."

The extraordinarily low entropy of the Universe at the Big Bang is both an answer and an enormous question. "The thing we understand the least about the nature of time, is why the Big Bang had low entropy, why the early Universe was like that," says Carroll. "And I think honestly, as a working cosmologist, I think that my fellow cosmologists have dropped the ball on this one. They don't really take that problem seriously enough."

Carroll published a paper in 2004 with his colleague Jennifer Chen, in which they aimed to explain why the Universe had such low entropy close to the Big Bang, rather than just assuming or accepting this was the case. "There's plenty of loopholes in the theory, plenty of aspects of it that are not completely baked – but I also think it is by far the best theory on the market," says Carroll. "It doesn't cheat."

Other cosmologists agree that it is indeed time to turn serious thought to this problem of the Universe's low entropy origins. "The likelihood of our current Universe having initial conditions of this kind, and not any other kind, is around one in 10 to the 10 to 124 (1:10^10^124)," says Cortês. (Another way of saying it is that the event had a probability of 0.00…01 – with 10^(10^124) zeroes omitted – a number so large it's awkward to express in conventional maths, Cortês notes.) "I mean I could safely say, this is the largest number in modern physics, outside of philosophy or mathematics."

Simply taking such unlikely low-entropy origins as given is a grand case of "shoving the problem under the rug", Cortês says. "If physicists keep doing this, after a while it's going to be a very big pile under the rug. It's left to us cosmologists to explain why time only moves forward."

Even if we don't yet know why, the Universe's low entropy past is a plausible source of time's arrow. Like most things that have a beginning, the arrow will also have an end. The first person to spot this was, once again, the Austrian physicist Ludwig Boltzmann.

"Boltzmann thought, 'ah, entropy is growing in the Universe and maybe it's going to maximum at some point'," says Rovelli. At that point, heat would be evenly distributed throughout the Universe, no longer flowing from one place to another.

There would be no energy available in a useful form for doing work – in other words, almost nothing interesting would be happening throughout the entire Universe. As astrophysicist Katie Mack describes it, "As that process continues, everything is decaying so much that all that’s left is the waste heat of everything that ever existed in the Universe." This fate is known as the thermal death of the Universe, or heat death.

"Stars will stop burning, nothing will happen anymore. There will be nothing but small thermal fluctuations," says Rovelli. "Suppose this happens – and we don't know for certain if it's going to happen, but suppose it does – should we say that there is no time direction there? Of course there's no time direction, because every phenomenon that happened one way could also go one way or the other. Nothing will distinguish the two directions of time."

This is perhaps the strangest thing about the arrow of time: "It only lasts for a little while," says Carroll.

It's very hard to picture what might happen if the arrow of time eventually vanishes. "When we think we produce heat in our neurons," says Rovelli. "Thinking is a process in which the neuron needs entropy to work. Our sense of time passing is just what entropy does to our brain."

The arrow of time that arises from entropy brings us a long way closer to understanding why time only goes forward. But there may be more arrows of time than this one – in fact there is arguably an entire volley of arrows of time pointing from the past to the future. To understand these, we have to step from physics into philosophy.

HUMAN TIME

The ways that we intuitively understand and experience time shouldn't be taken lightly, says Jenann Ismael, professor of philosophy at Columbia University, New York. If you think about your own experience of time, you may soon be able to recognise several of the psychological arrows that form a core part of human experience. One of these arrows is what Ismael terms "flow".

"If you look out at the world, you don't experience a purely static representation of the instantaneous state of the world," she says, like in a movie made up of a number of static frames every second. "We see directly that the world is changing."

This experience of the flow of time is built into our perception. "Vision isn't like a movie camera at all," says Ismael. "Actually what happens is your brain is collecting information over some temporal period. It's integrating that information so that at any given moment, what you're seeing is a computation that the brain has done. So that you not only see that things are moving, you see how fast they're moving, the direction in which they're moving. So the whole time, your brain is integrating information over temporal intervals and giving you the result. So you see time, in a way."

There's a second feature of time that Ismael distinguishes from flow, which she terms "passage".

The idea of passage is closely bound up with time-oriented experiences such as memory and anticipation. Take the example of a wedding, or any much-anticipated life event. Our experience of these moments has many layers – from the fractious planning stages, to the intensity of the day itself, to recollections that stay with us for years. There is a directionality to these different experiences: the way we anticipate an event in the future is fundamentally different from how we remember it when it's passed.

"All of that is part of what I think of as the experience of passage, this idea that we experience every event as anticipated from the past, experienced in the present, remembered in retrospect," says Ismael. "It's kind of Proustian in its density."

These aspects of the directionality of psychological time – as well as many others, like the sense of openness we have about the future but not the past – could all trace their roots back to the arrow of time born of the Industrial Revolution.

"I think it does all come back to entropy," says Ismael. "I see no reason now to think that the kinds of arrows that are involved in human psychology are anything but ultimately rooted in the entropic arrow. But it's an empirical question. This project to understand human experience in relation to the entropic arrow, I've no reason to think it's going to fail."

That project is what Carroll hopes to do, taking several features of our experience of time and relating them back to entropy. His first target is causality, another element of the arrow of time, as causes happen before their effects.

To say the least, this project is a major undertaking for all physicists and philosophers involved. And still, lurking in the shadows behind all such efforts, there remains that nagging question about why entropy was so low in the earliest Universe.

"I think we understand why we have this sense of flowing," says Rovelli. "We understand why the past seems fixed to us that the future seems open. We understand why there are irreversible phenomena, and we can reduce all that to the second law of thermodynamics, to the rise of entropy.

"It's very much related to the fact that if we trace it back, back, back, to fact that the Universe started very small, in a very peculiar situation. Then somehow, it's falling down from that peculiar situation.

"But of course there's one question open, I mean, why? Why did it start in that particular way?"

Link to original article here:
https://www.bbc.com/future/article/20221003-why-does-time-go-forwards-not-backwards

R.I.P. Stephen Hawking

We lost one of the most brilliant minds in history. He died on pi Day...seems fitting.

We Are Stardust

"The atoms of our bodies are traceable to stars that manufactured them in their cores and exploded these enriched ingredients across our galaxy, billions of years ago. For this reason, we are biologically connected to every other living thing in the world. We are chemically connected to all molecules on Earth. And we are atomically connected to all atoms in the universe. We are not figuratively, but literally stardust."
--Neil deGrasse Tyson

"The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff."
--Carl Sagan

"Everything we are and everything in the universe and on Earth originated from stardust, and it continually floats through us even today. It directly connects us to the universe, rebuilding our bodies over and again over our lifetimes."
--Iris Schrijver, author of LIVING WITH THE STARS: HOW THE HUMAN BODY IS CONNECTED TO THE LIFE CYCLES OF THE EARTH, THE PLANETS, AND THE STARS

"We are stardust/ We are golden/ And we've got to get ourselves/ Back to the garden"
--Joni Mitchell

Images produced by Lematworks
https://lematworks.myportfolio.com/

"All Scientists Should Be Militant Atheists" by Lawrence M. Kruss

From The New Yorker.
Thank you, Lawrence!


SEPTEMBER 8, 2015
All Scientists Should Be Militant Atheists
BY LAWRENCE M. KRAUSS

As a physicist, I do a lot of writing and public speaking about the remarkable nature of our cosmos, primarily because I think science is a key part of our cultural heritage and needs to be shared more broadly. Sometimes, I refer to the fact that religion and science are often in conflict; from time to time, I ridicule religious dogma. When I do, I sometimes get accused in public of being a “militant atheist.” Even a surprising number of my colleagues politely ask if it wouldn’t be better to avoid alienating religious people. Shouldn’t we respect religious sensibilities, masking potential conflicts and building common ground with religious groups so as to create a better, more equitable world?

I found myself thinking about those questions this week as I followed the story of Kim Davis, the county clerk in Kentucky who directly disobeyed a federal judge’s order to issue marriage licenses to gay couples, and, as a result, was jailed for contempt of court. (She was released earlier today.) Davis’s supporters, including the Kentucky senator and Presidential candidate Rand Paul, are protesting what they believe to be an affront to her religious freedom. It is “absurd to put someone in jail for exercising their religious liberties,” Paul said, on CNN.

The Kim Davis story raises a basic question: To what extent should we allow people to break the law if their religious views are in conflict with it? It’s possible to take that question to an extreme that even Senator Paul might find absurd: imagine, for example, a jihadist whose interpretation of the Koran suggested that he should be allowed to behead infidels and apostates. Should he be allowed to break the law? Or—to consider a less extreme case—imagine an Islamic-fundamentalist county clerk who would not let unmarried men and women enter the courthouse together, or grant marriage licenses to unveiled women. For Rand Paul, what separates these cases from Kim Davis’s? The biggest difference, I suspect, is that Senator Paul agrees with Kim Davis’s religious views but disagrees with those of the hypothetical Islamic fundamentalist.

The problem, obviously, is that what is sacred to one person can be meaningless (or repugnant) to another. That’s one of the reasons why a modern secular society generally legislates against actions, not ideas. No idea or belief should be illegal; conversely, no idea should be so sacred that it legally justifies actions that would otherwise be illegal. Davis is free to believe whatever she wants, just as the jihadist is free to believe whatever he wants; in both cases, the law constrains not what they believe but what they do.

In recent years, this territory has grown murkier. Under the banner of religious freedom, individuals, states, and even—in the case of Hobby Lobby—corporations have been arguing that they should be exempt from the law on religious grounds. (The laws from which they wish to claim exemption do not focus on religion; instead, they have to do with social issues, such as abortion and gay marriage.) The government has a compelling interest in insuring that all citizens are treated equally. But “religious freedom” advocates argue that religious ideals should be elevated above all others as a rationale for action. In a secular society, this is inappropriate.

The Kim Davis controversy exists because, as a culture, we have elevated respect for religious sensibilities to an inappropriate level that makes society less free, not more. Religious liberty should mean that no set of religious ideals are treated differently from other ideals. Laws should not be enacted whose sole purpose is to denigrate them, but, by the same token, the law shouldn’t elevate them, either.

In science, of course, the very word “sacred” is profane. No ideas, religious or otherwise, get a free pass. The notion that some idea or concept is beyond question or attack is anathema to the entire scientific undertaking. This commitment to open questioning is deeply tied to the fact that science is an atheistic enterprise. “My practice as a scientist is atheistic,” the biologist J.B.S. Haldane wrote, in 1934. “That is to say, when I set up an experiment I assume that no god, angel, or devil is going to interfere with its course and this assumption has been justified by such success as I have achieved in my professional career.” It’s ironic, really, that so many people are fixated on the relationship between science and religion: basically, there isn’t one. In my more than thirty years as a practicing physicist, I have never heard the word “God” mentioned in a scientific meeting. Belief or nonbelief in God is irrelevant to our understanding of the workings of nature—just as it’s irrelevant to the question of whether or not citizens are obligated to follow the law.

Because science holds that no idea is sacred, it’s inevitable that it draws people away from religion. The more we learn about the workings of the universe, the more purposeless it seems. Scientists have an obligation not to lie about the natural world. Even so, to avoid offense, they sometimes misleadingly imply that today’s discoveries exist in easy harmony with preëxisting religious doctrines, or remain silent rather than pointing out contradictions between science and religious doctrine. It’s a strange inconsistency, since scientists often happily disagree with other kinds of beliefs. Astronomers have no problem ridiculing the claims of astrologists, even though a significant fraction of the public believes these claims. Doctors have no problem condemning the actions of anti-vaccine activists who endanger children. And yet, for reasons of decorum, many scientists worry that ridiculing certain religious claims alienates the public from science. When they do so, they are being condescending at best and hypocritical at worst.

This reticence can have significant consequences. Consider the example of Planned Parenthood. Lawmakers are calling for a government shutdown unless federal funds for Planned Parenthood are stripped from spending bills for the fiscal year starting October 1st. Why? Because Planned Parenthood provides fetal tissue samples from abortions to scientific researchers hoping to cure diseases, from Alzheimer’s to cancer. (Storing and safeguarding that tissue requires resources, and Planned Parenthood charges researchers for the costs.) It’s clear that many of the people protesting Planned Parenthood are opposed to abortion on religious grounds and are, to varying degrees, anti-science. Should this cause scientists to clam up at the risk of further offending or alienating them? Or should we speak out loudly to point out that, independent of one’s beliefs about what is sacred, this tissue would otherwise be thrown away, even though it could help improve and save lives?

Ultimately, when we hesitate to openly question beliefs because we don’t want to risk offense, questioning itself becomes taboo. It is here that the imperative for scientists to speak out seems to me to be most urgent. As a result of speaking out on issues of science and religion, I have heard from many young people about the shame and ostracism they experience after merely questioning their family’s faith. Sometimes, they find themselves denied rights and privileges because their actions confront the faith of others. Scientists need to be prepared to demonstrate by example that questioning perceived truth, especially “sacred truth,” is an essential part of living in a free country.

I see a direct link, in short, between the ethics that guide science and those that guide civic life. Cosmology, my specialty, may appear to be far removed from Kim Davis’s refusal to grant marriage licenses to gay couples, but in fact the same values apply in both realms. Whenever scientific claims are presented as unquestionable, they undermine science. Similarly, when religious actions or claims about sanctity can be made with impunity in our society, we undermine the very basis of modern secular democracy. We owe it to ourselves and to our children not to give a free pass to governments—totalitarian, theocratic, or democratic—that endorse, encourage, enforce, or otherwise legitimize the suppression of open questioning in order to protect ideas that are considered “sacred.” Five hundred years of science have liberated humanity from the shackles of enforced ignorance. We should celebrate this openly and enthusiastically, regardless of whom it may offend.

If that is what causes someone to be called a militant atheist, then no scientist should be ashamed of the label.

Lawrence M. Krauss is the foundation professor and director of the Origins Project at Arizona State University, and the chair of the board of sponsors of the Bulletin of the Atomic Scientists. His books include “The Physics of Star Trek” and, most recently, “A Universe from Nothing.”


Original article here:
http://www.newyorker.com/news/news-desk/all-scientists-should-be-militant-atheists

Sun and Blue Skies...ANYWHERE

Since the atmosphere of our little planet is made up of 78% nitrogen, 21% oxygen, and 1% other gases, the sunlight that passes through the atmosphere has a very specific and identifiable quality and color...and creates our familiar and comforting blue sky. And now, physicist Professor Paolo Di Trapani of Insubria University at Como, Italy has created a revolutionary technological discovery that brings sunlight and blue skies to any space, no matter where it is. Even underground. After a decade of research and development, Professor Di Trapani uses an LED light source filtered through several layers of nanoparticles (which function as the layers of nitrogen, oxygen, and miscellaneous gases in our atmosphere) to mimic exactly the sun as an orb of light in a blue sky. The results are simply jaw dropping--look at the photos below that CoeLux assures us are not Photoshopped. They are raw photos of the actual product.

In November 2014, CoeLux was crowned “Light Source Innovation of the year” at the Lux Awards, and rightly so. The implications for this invention are staggering and will change interior architecture forever. Subterranean homes and businesses, parts of the world that don't see much sunlight for reasons of latitude or pollution, or areas of buildings where a roof line or second story will not permit a skylight will all benefit tremendously from this marvel.

CoeLux is currently offered in three levels, each with a regional, or geographical cast. CoeLux 60 creates sunlight at a 60 degree angle to create near-equatorial tropical light. For light with a Mediterranean feel, CoeLux 45 delivers a 45 degree beam. And CoeLux 30 features a 30 degree angled beam of light reminiscent of Nordic light. But the company is at work producing a commercially feasible version for regular applications.

Watch this short video about the product. It is just mind boggling...keep in mind that you are not seeing sun and sky but an artificial light source that seems to be anything but.

http://www.coelux.com/

Science and Life Beyond

A Physicist’s View of the Afterlife: Weird Quantum Physics
By Tara MacIsaac, Epoch Times | September 5, 2014

NEWPORT BEACH, Calif.—Dr. Alan Ross Hugenot has spent decades contemplating the conundrums of physics, along with the enigma of human consciousness.

Hugenot holds a doctorate of science in mechanical engineering, and has had a successful career in marine engineering, serving on committees that write the ship-building standards for the United States.

“I did things using Newtonian physics to create ships,” he said, “but the whole time, I knew better. There’s this whole other world that our five senses don’t register.” He gave a talk on the science of the afterlife at the International Association for Near-Death Studies (IANDS) 2014 Conference in Newport Beach, Calif., on Aug. 29.

Exploring the scientific theories related to this other world, Hugenot has wondered whether the consciousness of living human beings as well as the “souls” of the dead reside in dark matter or dark energy. He has pondered the implications of the power our consciousness seems to have over physical reality.

Hugenot told of a near-death experience in the 1970s during which he experienced part of this other world. He found it “more real than this place.”

These matters aren’t only intellectual curiosities for Hugenot; they bear on a profound experience that has changed his worldview.

Hugenot summarized some theories in physics, interpreting how they may point to the existence of a consciousness independent of the brain and to the existence of an afterlife on another plane. He noted that further investigation (reliant on further funding) would be needed to verify his postulates. He also noted challenges in trying to verify these ideas in a traditional scientific framework.

How Your Consciousness Could Exist in a ‘Cloud’

Hugenot said the human consciousness may function like the data we store in the cloud. That data can be accessed from multiple devices—your smartphone, your tablet, your desktop computer.

During a near-death experience, theorized Hugenot, the mind may be fleeing a dangerous situation. We can “flip the switch and go to the other computer,” he said.

“The nexus of my consciousness is in my head, but the locus of my consciousness—where is it really? It’s outside my body. Because inside and outside is an illusion.”

Space may not exist, or at least not in the way we commonly understand it, he said, citing Dr. John Bell’s non-locality theorem. “[It's a] hard one to get; we love our space,” he joked.

Non-locality refers to the ability of two objects to instantaneously know about each other’s states, even if they’re separated by vast distances. It is related to the phenomenon of entanglement: particle A and particle B interact, and thereafter remain mysteriously bonded. When particle A undergoes a change, particle B undergoes the same change; A and B have, in many ways, lost their individuality and behave as a single entity.

Bell’s theorem has been verified by many scientists over the years and is part of mainstream quantum physics. Hugenot’s ideas about the consciousness existing inside and outside of the human body at the same time build on this theorem, but remain outside the mainstream.

Is the Afterlife in Dark Matter, or Maybe in Another Dimension?

What scientists have observed accounts for an estimated 4 percent of our universe. Dark energy and dark matter comprise the other 96 percent. Scientists don’t really know what dark energy and matter are, and their existence is only perceived because of the effects they appear to have on observable matter.

Hugenot said: “This undiscerned 96 percent of the universe … gives us plenty of room for both consciousness and the afterlife to exist in.”

Perhaps the consciousness exists in another dimension, Hugenot said. String Theory, much-discussed in mainstream physics, holds that other dimensions exist beyond the four-dimensional concept of the universe. String Theory views the universe as a world of very thin, vibrating strings. The strings are thought to project from a lower-dimensional cosmos, one that is simpler, flatter, and without gravity.

Link to the original full article:
http://www.theepochtimes.com/n3/936107-a-physicists-view-of-the-afterlife-weird-quantum-physics/

Brian Cox says...