Why Your Brain Is Slow (And Fast, Too)
Carl Zimmer is a science writer, lecturer, and frequent guest on such radio programs as Fresh Air and This American Life. His books include "Soul Made Flesh," "Evolution: The Triumph of an Idea," and "Parasite Rex." In addition to writing books, Zimmer contributes articles to The New York Times, as well as magazines including National Geographic, Time, Scientific American, Science, and Popular Science. He also writes an award-winning blog, The Loom. From 1994 to 1998 Zimmer was a senior editor at Discover, where he remains a contributing editor and writes a monthly column about the brain.
Zimmer is a lecturer at Yale University, where he teaches writing about science and the environment. He is also the first Visiting Scholar at the Science, Health, and Environment Reporting Program at New York University’s Arthur L. Carter Journalism Institute.
Zimmer is a Big Think Delphi Fellow.
Question: How and why does “the speed of thought” vary across the brain?
Carl Zimmer: We tend to think of our experience as just sort of happening to us instantaneously, so I don’t think when I talk to someone that they are across the room and therefore there is a certain amount of time that it takes for me to hear what they’re saying. We just think that everything happens in real time, but you know the fact is that we perceive the world through this organ the brain and it works a lot… kind of like a telegraph, so if you were to send a message to somebody with a telegraph and you started tapping out your message they’re not going to get the message immediately. It’s going to take time for all those dots and dashes to make their way down the wire and get to the other end. We have wiring in our own brains. We have neurons, which work a lot like telegraph wires in some ways. They actually use kind of a biological set of dots and dashes. They have little spikes of voltage that we use to process information, so you know if I see something it takes awhile for it to get from my eye into my brain and then it takes awhile for it to spread to different parts of the brain and then for that information to get integrated in lots of different ways.
The way that you can think about this really vividly was brought home to me once when I was talking to a neuroscientist named Michael de Zuniga, and he just basically, all he did was, he took his finger and he stuck it on his nose and he said, “You know it’s interesting is that you feel your finger touching your nose and you feel your nose touching your finger at the same time, but the fact is that the signal from your fingertip had a lot longer to go than the signal from your nose and yet they got to your brain and it felt like it was happening at the same time.” So your thoughts have this speed and your brain has to… your brain had to deal with that speed, had to deal with that delay. Now you might think well you know we should just have brains that work as fast as possible, so we should just have you know fast neurons and just to speed everything up you know because time is money, because you know your survival might depend on a fast signal. There is a problem though is that speeding up these signals doesn’t come for free, so one strategy that we have evolved for fast thought as it were is to insulate our neurons and this is actually you know something that is used a lot in engineering. I mean if you don’t want a signal to dissipate out of a wire you want to insulate it. We insulate our neurons with sort of fatty molecules, like myelin. Another thing you can do is you can actually take another trick that telegraph engineers first developed which is to make your neurons thick, so signals will go through a fast wire… I’m sorry. Signals will go through a fat wire quickly faster than a thinner wire. Now the problem is that insulating your neurons and making them fat is a big cost. It takes a lot of energy to do that, energy you could be using for other things and not only that, but you know your brain is a pretty tightly packed place. If you were to you know double or triple the width of your neurons your head might not be able to fit through a doorway. So evolution has come up with these wonderful optimizing tradeoffs. Our signals work quickly in some neurons and slower in others. We have sort of found this nice balance to speed it up as fast as possible without making the cost too high and the fact is that you know when I put my nose… touch my finger to my nose I actually don’t want the signal from my nose to go too fast. I actually want the timing to make everything seem to be happening at once, so actually sometimes you need to slow thought down a little bit in order for the world to make any sense.
Recorded on January 6, 2010
Interviewed by Austin Allen
Your finger is farther from your nose than your brain. So when your finger touches your nose, why do both organs feel the sensation at the same time?
Younger Americans support expanding the Supreme Court and serious political reforms, says new poll.
- Americans under 40 largely favor major political reforms, finds a new survey.
- The poll revealed that most would want to expand the Supreme Court, impose terms limits, and make it easier to vote.
- Millennials are more liberal and reform-centered than Generation Z.
Logic puzzles can teach reasoning in a fun way that doesn't feel like work.
- Logician Raymond Smullyan devised tons of logic puzzles, but one was declared by another philosopher to be the hardest of all time.
- The problem, also known as the Three Gods Problem, is solvable, even if it doesn't seem to be.
- It depends on using complex questions to assure that any answer given is useful.
The Three Gods Problem<iframe width="730" height="430" src="https://www.youtube.com/embed/UyOGZk7WbIk" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe><p> One of the more popular wordings of the problem is:<br> <br> "Three gods A, B, and C are called, in no particular order, True, False, and Random. True always speaks truly, False always speaks falsely, but whether Random speaks truly or falsely is a completely random matter. Your task is to determine the identities of A, B, and C by asking three yes-no questions; each question must be put to exactly one god. The gods understand English, but will answer all questions in their own language, in which the words for <em>yes</em> and <em>no</em> are <em>da</em> and <em>ja</em>, in some order. You do not know which word means which."<br> <br> Boolos adds that you are allowed to ask a particular god more than one question and that Random switches between answering as if they are a truth-teller or a liar, not merely between answering "da" and "ja." <br> <br> Give yourself a minute to ponder this; we'll look at a few answers below. Ready? Okay. <strong><br> <br> </strong>George Boolos' <a href="https://www.pdcnet.org/8525737F00588A37/file/31B21D0580E8B125852577CA0060ABC9/$FILE/harvardreview_1996_0006_0001_0060_0063.pdf" target="_blank" rel="noopener noreferrer">solution</a> focuses on finding either True or False through complex questions. </p><p> In logic, there is a commonly used function often written as "iff," which means "if, and only if." It would be used to say something like "The sky is blue if and only if Des Moines is in Iowa." It is a powerful tool, as it gives a true statement only when both of its components are true or both are false. If one is true and the other is false, you have a false statement. </p><p> So, if you make a statement such as "the moon is made of Gorgonzola if, and only if, Rome is in Russia," then you have made a true statement, as both parts of it are false. The statement "The moon has no air if, and only if, Rome is in Italy," is also true, as both parts of it are true. However, "The moon is made of Gorgonzola if, and only if, Albany is the capitol of New York," is false, because one of the parts of that statement is true, and the other part is not (The fact that these items don't rely on each other is immaterial for now).</p><p> In this puzzle, iff can be used here to control for the unknown value of "da" and "ja." As the answers we get can be compared with what we know they would be if the parts of our question are all true, all false, or if they differ. </p><p> Boolos would have us begin by asking god A, "Does "da" mean yes if and only if you are True if and only if B is Random?" No matter what A says, the answer you get is extremely useful. As he explains: <br> </p><p> "If A is True or False and you get the answer da, then as we have seen, B is Random, and therefore C is either True or False; but if A is True or False and you get the answer ja, then B is not Random, therefore B is either True or False… if A is Random and you get the answer da, C is not Random (neither is B, but that's irrelevant), and therefore C is either True or False; and if A is Random...and you get the answer ja, B is not random (neither is C, irrelevantly), and therefore B is either True or False."<br> <br> No matter which god A is, an answer of "da" assures that C isn't Random, and a response of "ja" means the same for B. </p><p> From here, it is a simple matter of asking whichever one you know isn't Random questions to determine if they are telling the truth, and then one on who the last god is. Boolos suggests starting with "Does da mean yes if, and only if, Rome is in Italy?" Since one part of this is accurate, we know that True will say "da," and False will say "ja," if faced with this question. </p><p> After that, you can ask the same god something like, "Does da mean yes if, and only if, A is Random?" and know exactly who is who by how they answer and the process of elimination. </p><p> If you're confused about how this works, try going over it again slowly. Remember that the essential parts are knowing what the answer will be if two positives or two negatives always come out as a positive and that two of the gods can be relied on to act consistently. </p><p> Smullyan wrote several books with other logic puzzles in them. If you liked this one and would like to learn more about the philosophical issues they investigate, or perhaps if you'd like to try a few that are a little easier to solve, you should consider reading them. A few of his puzzles can be found with explanations in this <a href="https://www.nytimes.com/interactive/2017/02/11/obituaries/smullyan-logic-puzzles.html" target="_blank" rel="noopener noreferrer">interactive</a>. </p>
The theory could resolve some unanswered questions.
- Most stars begin in binary systems, why not ours?
- Puzzles posed by the Oort cloud and the possibility of Planet 9 may be solved by a new theory of our sun's lost companion.
- The sun and its partner would have become separated long, long ago.
If most stars form in binary pairs, what about our Sun? A new paper presents a model supporting the theory that the Sun may have started out as one member of a temporary binary system. There's a certain elegance to the idea — if it's true, this origin story could resolve some vexing solar-system puzzles, among them the genesis of the Oort Cloud, and the presence of massive captured objects like a Planet Nine.
The paper is published in Astrophysical Journal Letters.
The Oort cloud
Image source: NASA
Scientist believe that surrounding the generally flat solar system is a spherical shell comprised of more than a trillion icy objects more than a mile wide. This is the Oort cloud, and it's likely the source of our solar system's long-term comets — objects that take 200 years or more to orbit the Sun. Inside that shell and surrounding the planets is the Kuiper Belt, a flat disk of scattered objects considered the source of shorter-term comets.
Long-term comets come at us from all directions and astronomers at first suspected their origins to be random. However, it turns out their likely trajectories lead back to a shared aphelion between 2,000 astronomical units (AU) from the Sun to about 100,000 AU, with their different points of origin revealing the shell shape of the Oort cloud along that common aphelion. (An astronomical unit is the distance from the Sun to the Earth.)
No object in the Oort cloud has been directly observed, though Voyager 1 and 2, New Horizons, and Pioneer 10 and 11 are all en route. (The cloud is so far away that all five of the craft will be dead by the time they get there.) To derive a clearer view of the Oort cloud absent actually imagery, scientists utilize computer models based on planetary orbits, solar-system formation simulations, and comet trajectories.
It's generally assumed that the Oort cloud is comprised of debris from the formation of the solar system and neighboring systems, stuff from other systems that we somehow captured. However, says paper co-author Amir Siraj of Harvard, "previous models have had difficulty producing the expected ratio between scattered disk objects and outer Oort cloud objects." As an answer to that, he says, "the binary capture model offers significant improvement and refinement, which is seemingly obvious in retrospect: most sun-like stars are born with binary companions."
"Binary systems are far more efficient at capturing objects than are single stars," co-author Ari Loeb, also of Harvard, explains. "If the Oort cloud formed as [indirectly] observed, it would imply that the sun did in fact have a companion of similar mass that was lost before the sun left its birth cluster."
Working out the source of the objects in the Oort cloud is more than just an interesting astronomical riddle, says Siraj. "Objects in the outer Oort Cloud may have played important roles in Earth's history, such as possibly delivering water to Earth and causing the extinction of the dinosaurs. Understanding their origins is important."
Image source: Caltech/R. Hurt (IPAC)/NASA
The gravitational pull resulting from a binary companion to the Sun may also help explain another intriguing phenomenon: the warping of orbital paths either by something big beyond Pluto — a Planet 9, perhaps — or smaller trans-Neptunian objects closer in, at the outer edges of the Kuiper Belt.
"The puzzle is not only regarding the Oort clouds, but also extreme trans-Neptunian objects, like the potential Planet Nine," Loeb says. "It is unclear where they came from, and our new model predicts that there should be more objects with a similar orbital orientation to [a] Planet Nine."
The authors are looking forward to the upcoming Vera C. Rubin Observatory (VRO) , a Large Synoptic Survey Telescope expected to capture its first light from the cosmos in 2021. It's expected that the VRO will definitively confirm or dismiss the existence of Planet 9. Siraj says, "If the VRO verifies the existence of Planet Nine, and a captured origin, and also finds a population of similarly captured dwarf planets, then the binary model will be favored over the lone stellar history that has been long-assumed."
Missing in action
Lord and Siraj consider it unsurprising that we see no clear sign of the Sun's former companion at this point. Says Loeb, "Passing stars in the birth cluster would have removed the companion from the sun through their gravitational influence. He adds that, "Before the loss of the binary, however, the solar system already would have captured its outer envelope of objects, namely the Oort cloud and the Planet Nine population."
So, where'd it go? Siraj answers, "The sun's long-lost companion could now be anywhere in the Milky Way."
Another amazing tardigrade survival skill is discovered.
- Apparently, some water bears can even beat extreme UV light.
- It may be an adaptation to the summer heat in India.
- Special under-skin pigments neutralize harmful rays.
Stressor testing<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDU1MzIzMS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyMjc2MDc4Mn0.5R6DAfzsq29zvETCEH1sR9rprcnJv_L0KyUW2qedslE/img.jpg?width=980" id="c6b71" class="rm-shortcode" data-rm-shortcode-id="e7afe644fc94631ed9ea6837ed3920d3" data-rm-shortcode-name="rebelmouse-image" alt="water bear illustration" />
3D illustration of a tardigrade
Credit: Dotted Yeti/Shutterstock<p>It seems at times like scientists enjoy playing the "let's see if <em>this</em> kills them" game with tardigrades, a game that humans usually lose. After searching the campus of the Indian Institute of Science, researchers gathered some water bears and brought them back to the lab to see what they could handle.</p><p>The scientists found that after they exposed <a href="http://cshprotocols.cshlp.org/content/2018/11/pdb.emo102301.full" target="_blank"><em>Hypsibius exemplaris</em></a> tardigrades to very high doses — 1 kilojoule (kJ) per square meter — of UV light for about 15 minutes, they would in fact die over the next 24 hours. However, when they aimed the same blasts at the reddish-brown tardigrades…nothing. The humans even quadrupled the UV intensity and, nope, they tracked the water bears for 30 days, and a majority of them, 60 percent, were still fine.</p><p>As is often the case with tardigrades, the question is how?</p>
Turning deadly light blue<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDU1MzIwMy9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxMTM1NTE2N30.n8FiCLgp5aTqmYby2bjpeu9QJRTV7KzaB9tmTHBzWtk/img.jpg?width=980" id="5d4cc" class="rm-shortcode" data-rm-shortcode-id="7aa8735a958123bcfb269920eb4d2aed" data-rm-shortcode-name="rebelmouse-image" />
Tardigrade's normal appearance (left), and under inverted fluorescence (right)
Credit: Suma et al., Biology Letters (2020)<p>When the researchers examined the tardigrades under an inverted fluorescence microscope they found that when they were exposed to UV light, they became blue. The researchers' hypothesis is that these tardigrades carry fluorescent pigments beneath their skin that they deploy as necessary to transform UV light into simple benign, blue light. It may be that this ability has emerged as an evolutionary response to southern tropical India's often-extreme heat. The study says that typical summer-day UV levels in this region are about 4kJ per square meter.</p><p>Of the 40 percent of the reddish-brown tardigrades that had died before 30 days — mostly after about 20 days — the scientists concluded they had less pigment with which to neutralize UV light.</p><p>When the scientists extracted the pigment from the UV champions and coated some <em>Hypsibius exemplaris</em> tardigrades with the stuff, their resistance to UV exposure was also enhanced, boosting their survival rate to almost twice that of their uncoated brethren.</p><p>Autofluorescence has been found in other animals — parrots, scorpions, chameleons, and frogs, among others — so it's not completely unheard of. In parrots, for example, autofluorescence is hypothesized to be involved in tweaking coloration during mating rituals. Still, surprise, tardigrades seem to be putting it to unusual use by employing it for UV protection. </p>