A few decades ago, scientists learned about a curious form of carbon, known as carbyne, thought to be even stronger than graphene and diamond, two of the strongest materials known to man. They managed to synthesize chains of it in the lab and some astronomers even think they’ve detected its signature in space, but no one really understood its properties—until now. Much like graphene, carbyne is just one atom thick, giving it incredible surface area for any given mass. Scientists also estimate that it is nearly 3 times stiffer than diamond. Unfortunately, carbyne chains are not entirely stable and can react explosively when they touch another chain, though Liu and her team say that will likely only happen at higher temperatures. At room temperature, the substance condenses in a matter of days. That should open up all sorts of uses for this novel material.
It’s just another fascinating discovery for carbon, the chemical basis of all known life.
The mathematical laws of physics work just as well for events going forward or going backward in time. Yet in the real world, hot coffee never unmixes itself from cold milk. A theorist publishing in the 21 August Physical Review Letters offers a new explanation for this apparent conflict between the time-symmetry of the physical laws and the forward “arrow of time” we see in everyday events. When viewed in quantum terms, events that increase the entropy of the Universe leave records of themselves in their environment. The researcher proposes that events that go “backward,” reducing entropy, cannot leave any trace of having occurred, which is equivalent to not happening.
Thermodynamically speaking, whenever two bodies of unequal temperature are joined together, energy flows between them until the two temperatures equalize. Associated with this heat diffusion is an increase in the quantity known as entropy. As far as we know, heat never spontaneously flows in reverse, and the entropy of the Universe always goes up.
Reversing time’s arrow would be equivalent to lowering entropy, for example if an object at uniform temperature were to spontaneously warm up in one spot and cool elsewhere. In a 19th century thought experiment, a powerful imp called Maxwell’s demon is able to perform such a separation for a gas by knowing the position and speed of every gas molecule in a box with a partition. Using a shutter over a hole in the partition, the demon restricts high-energy molecules to one side and allows the low-energy molecules to collect on the other side. It turns out that the demon would have to expend energy and raise its own entropy, so the Universe’s total entropy would still rise.
In the quantum world, an entropy-lowering demon would have a different chore, because in the quantum mechanical version of entropy, it isn’t heat that flows when entropy changes, it’s information. Lorenzo Maccone of the University of Pavia, Italy, and the Massachusetts Institute of Technology, describes a thought experiment to illustrate the consequences of reducing quantum entropy. An experimenter, Alice, measures the spin state of an atom sent by her friend Bob, who is otherwise isolated from Alice’s laboratory. The atom is in a combined state (superposition) of spin-up and spin-down until Alice measures it as either up or down.
From Alice’s perspective, her lab gains a single bit of information from outside, and it’s then copied and recorded in her memory and on her computer’s hard drive. That information flow from atom to lab increases entropy, according to Alice. Maccone argues that because Bob doesn’t see the result, from his perspective the spin state of the atom never resolves itself into up or down. Instead it becomes quantum mechanically correlated, or “entangled,” with the quantum state of the lab. He sees no information flow and no change in entropy.
Bob plays the role of Maxwell’s demon; he has total control of the quantum state of her lab. To reduce the entropy of the lab from Alice’s point-of-view, Bob reverses the flow of that one bit of information by removing any record of the atom’s spin from Alice’s hard drive and her brain. He does so by performing a complicated transformation that disentangles the lab’s quantum state from that of the atom.
Maccone writes that such a reversal violates no laws of quantum physics. In fact, from Bob’s perspective, the quantum information of the atom plus Alice’s lab is the same whether or not the two are entangled–there is no change in entropy as viewed from the outside. Such reversals could happen in real life, Maccone says, but because the Universe–like Alice–would retain no memory of them, they would have no effect on how we perceive the world. His paper goes on to show mathematically how this reasoning applies in general, with the Universe taking the place of Alice.
Jos Uffink of Utrecht University in the Netherlands accepts some aspects of the work but is not completely convinced. “The observer might very well retain a partial memory of the event,” after the entropy-reducing process, he says. Still, he calls the approach of the paper “quite novel” and its conclusions “startling.” He says a vigorous debate continues about the relationship between information as an objective, physical quantity and the apparent “irreversibility” of so many events in the world around us.
For those who are interested in the sciences and want to dive into the field of physics in greater detail, the following classification of branches in the physical sciences is for you. And, if you don’t see a subject that most wholeheartedly applies to your own interests, then, please, by all means, develop your own new branch of special sciences! Good luck!
Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties (luminosity, density, temperature and chemical composition) of astronomical objects such as stars, galaxies, and the interstellar medium, as well as their interactions.
Atomic and molecular physics is the study of the structure and characteristics of atoms and molecules.
Biophysics the science of the application of the laws of physics to life processes.
Condensed-matter (solid-state) physics is the study of the physical properties of solids, such as electrical, dielectric, elastic, and thermal properties, and their understanding in terms of fundamental physical laws.
Cosmology is the study of the universe as a whole, of the contents, structure, and evolution of the universe from the beginning of time to the future.
Geophysics is the study of the physical characteristics and properties of the earth; including geodesy, seismology, meteorology, oceanography, atmospheric electricity, terrestrial magnetism, and tidal phenomena.
Mechanics is the branch of physics concerned with the motion of bodies in a frame of reference.
Statistical Mechanics is the discipline that attempts to relate the properties of macroscopic systems to their atomic and molecular constituents.
Theoretical physics attempts to understand the world by making a model of reality, used for rationalizing, explaining, and predicting physical phenomena through a “physical theory”.
Thermodynamics is the study of the effects of changes in temperature, pressure, and volume on physical systems at the macroscopic scale by analyzing the collective motion of their particles using statistics.
Once, someone asked me why I wanted him to make an impact on the people around him, declaring, “Why change the world when you can just make the best out of everyday life?” Well, let me start off by saying that everyday life on Earth is, in itself, an awe-inspiring and improbable entity. Out of all the possibilities of a universe with a unique set of physical laws, humanity found itself in existence within one of the most hostile settings one could ever imagine, not limited to one’s imagination. Had the cosmos opted to elevate the strength of the gravitational force by even a tiny factor, galaxies would be colliding at every corner and the hypothetically closed universe would be on track to ultimate cataclysm by way of the inevitable reversed expansion of space. Essentially, we’re lucky to be here. But, why are we here? Mature, knowledgeable, and ripe physicists would say that this is a stupid question, not far from “When is the plastic water bottle?” or “How is the pencil case?” On the contrary, my naïve mind, upon contemplating the question, became motivated to actually find an solid, objective ‘greater purpose’ for life as a whole. Immediately, I focused my attention on the more primitive life forms on Earth, such as fish, reptiles, single-celled organisms, and me as a baby. What is the underlying theme common to all of these creatures? The peculiarly intriguing drive to survive and, eventually, reproduce. Our primary goal is to produce more, more, and more of ourselves and to extend the physical imprint of our species over countless generations of life- the basis for biological evolution. The key ingredients of both natural selection and a lengthy period of time allow successful life forms to undergo creative, emotional, physical, and intellectual development. The entailments of this process can be depicted through a comparison between an everyday, working, human spouse and their child of two months. Let’s now input into the situation an x and y: time and level of happiness. At once, we ask ourselves, “What experiences would each entity undergo in the duration of a week and how would each entity react, in terms of happiness?” The graph would look something like this.
The infant would eat, sleep, and cry all day, to continue to survive. In fact, its activities would be limited to these few fundamental chores, in which experiences involving going to Hawaii for a vacation would be meaningless, to say the least, regarding the impact it has on the child’s level of happiness. The vacation offers little to nothing concerning the coincidentally congruent necessities and wants of the infant, centered around its drive for survival. Notably, this mindset is reflective of the everyday function of animal and plant life on Earth. In contrast, the needs and wants of the creatively, emotionally, physically and intellectually developed caregiver are completely mutually exclusive. Furthermore, a vacation to Hawaii would undoubtedly heighten the spouse’s happiness level, whereas having to clean the house upon return would have an impact of similar magnitude but unlike direction on the spouse’s mood. In addition, we can assume that the overall level of happiness would average out over a large enough period of time at about a 5 on the applicable scale, not to mention the total intake of happiness for the infant would, hypothetically, positively correspond to that of the spouse. So, why did the same species of human being evolve through the years to experience more highs and lows, when the end result is relatively neutral and the omnipresent purpose is to prolong their kind? Well, why are there objects on each end of the scale? Why are there pairs of symmetries that sum to zero, such as the equal and opposite forces described in Newton’s Third Law of motion, rather than zero itself? Believe it or not, there is something, instead of nothing, as of present.
The universe must have prescribed a greater purpose to us, providing humankind with the drive to explore its limits and to survive/reproduce so as to continue to be able to explore. Maybe, the universe wanted us to make what is presently unknown known. Maybe, the universe had a desire to be acknowledged for its fundamental beauty- for the simple fact that it exists and is something rather than nothing. As a human being, how would I achieve this? Empirically, I would explore the highs, lows, and all that I know to uncover greater truths as well as new mysteries to solve. Perhaps, after utmost creative, emotional, physical, and intellectual development, we may meet a limit acknowledging our own accomplishments throughout existence. Then again, it is and has always been about the process- not the end result. Perhaps, a greater purpose is for each individual to decide and the nature of existence is subjective in nature. Although we are plainly and quite irrefutably the end results of a cosmological accident, perhaps we are limitless in & amongst ourselves.
You’re almost unfathomably lucky to exist, in almost every conceivable way. Don’t take it the wrong way. You, me, and even the most calming manatee are nothing but impurities in an otherwise beautifully simple universe.
We’re lucky life began on Earth at all, of course, and that something as complex as humans evolved. It was improbable that your parents met each other and conceived you at just the right instant, and their parents and their parents and so on back to time immemorial. This is science’s way of reminding you to be grateful for what you have.
But even so, I have news for you: It’s worse than you think. Much worse.
Your existence wasn’t just predicated on amorousness and luck of your ancestors, but on an almost absurdly finely tuned universe. Had the universe opted to turn up the strength of the electromagnetic force by even a small factor, poof! Suddenly stars wouldn’t be able to produce any heavy elements, much less the giant wet rock we’re standing on. Worse, if the universe were only minutely denser than the one we inhabit, it would have collapsed before it began.
Worse still, the laws of physics themselves seem to be working against us. Ours isn’t just a randomly hostile universe, it’s an actively hostile universe.
My physicist colleagues and I like to pretend that the laws of physics are orderly and elegant. Indeed, I just published an entire book, The Universe in a Rear-view Mirror, about the beautiful symmetries of the universe. Programs like Nova or Slate’s own Bad Astronomy tend to focus on the knowable structure of how everything fits together.
The history of physics, in fact, is a marvel of using simple symmetry principles to construct complicated laws of the universe. Einstein quite famously was able to construct his entire theory of special relativity—the idea that ultimately gave us E=mc2 and explained the heat of the sun—from nothing more than the simple idea that there was no measurable distinction to be made between observers at rest and observers in uniform motion.
The long-overlooked 20th-century mathematician Emmy Noether proved the centrality of symmetry as a physical principle. And what is symmetry—at least as scientists understand it? The mathematician Hermann Weyl gave perhaps the most succinct definition:
“A thing is symmetrical if there is something you can do to it so that after you have finished doing it, it looks the same as before.”
Which sounds innocuous enough until you realize that if the entire universe were made symmetric, then all of the good features (e.g., you) are decidedly asymmetric lumps that ruin the otherwise perfect beauty of the cosmos.
The seemingly simple idea that the laws of the universe are the same everywhere in space and time turns out to yield justification for long-observed properties of the universe, like Newton’s first law of motion (“An object in motion stays in motion,” etc.) and first law of thermodynamics (the conservation of energy).
As the Nobel laureate Phil Anderson put it:
“It is only slightly overstating the case to say that physics is the study of symmetry.”
Everything is kinda the same? Every Friday night is like every other one? Sounds almost comforting. But it would be a mistake to be comforted by the symmetries of the universe. In truth, they are your worst enemies. Everything we know about those rational, predictable arrangements dictates that you shouldn’t be here at all.
How hostile is the universe to your fundamental existence?
Very. Even the simplest assumptions about our place in the universe seem to lead inexorably to devastating results.
The laws of physics seem to act equally in all directions. This is one of the great symmetries of nature. It gives rise to the inverse square law of gravity—the pull of gravity decreases proportionally to the square of the distance between two objects. Lights seem to drop off in brightness as the inverse square as well, which means that distant stars and galaxies naturally appear quite a bit dimmer than those nearby.
On the other hand, the farther away we look, the more galaxies we can conceivably encounter in our field of view. Add the two effects together, and the farther you look in any given direction, the more galaxies you see, even though each more distant one is individually dimmer. The cumulative brightness will appear greater and greater the farther you look. Taken to the logical extreme—the infinite recesses of space—in every direction you look you should eventually see a star, and the entire sky should appear as bright as the surface of the sun.
So why is the sky dark at night? That query isn’t quite as stupid as you might suppose. It’s called Olbers’ paradox, after Heinrich Olbers, who, in 1823, was one of the last people to discover it. (Johannes Kepler came up with a similar idea back in 1605, and the astronomer Thomas Dieges noticed a similar problem a quarter-century before that.)
If you suppose that astronomers are just playing math games, go to the middle of a forest. Nearby trees will look big. More distant trees will look small, but there are so many of them that if you’re far enough into the woods, you won’t be able to see out in any direction. Now suppose that those trees were on fire and were as bright as the sun. In Darkness of the Night: A Riddle of the Universe, the cosmologist Edward Harrison puts it rather poetically:
“In this inferno of intense heat, the Earth’s atmosphere would vanish in minutes, its oceans boil away in hours, and the Earth itself evaporate in a few years. And yet, when we survey the heavens, we find the universe plunged in darkness.”
The symmetry of the universe would bake us in no time at all, but an asymmetry rescues us. Kepler recognized that for the sky to be dark at all, the universe must be “enclosed and circumscribed by a wall or a vault.”
And so it is. That vault is the beginning of time.