What Should Be Explained Better?

By Sean Carroll | November 13, 2010 4:40 pm

I tweeted this on an impulse:

What is the one concept in science that you really think should be explained better to a wide audience?

At least 140 characters restricts people to really only suggesting one thing. But I don’t want to leave the blog readers out, so have a go. See if you can stick to just one!

CATEGORIZED UNDER: Science and Society
  • wldmr

    The fact that science asks “how?” rather than “why?” and therefore has no overlap with religion. People need to get over the idea that one somehow precludes the other.

    I don’t think that was quite what you were asking for, but there it is.

  • Brent Mosley

    Speciation. I have seen so many “definitions” that I’m not that even scientists agree on what the term means, let alone the public.

  • http://sarajdavis.net/ Non-Believer

    I’ve read a lot of about it, (pop books, not real science books) but I still have a hard time grasping quantum mechanics.

  • spyder

    What happened to string theory? Or perhaps, what is happening in string theory?

  • Magnus

    The difference between electrostatics and magnetism.

  • onymous


  • viggen

    Two things: Occam’s Razor and the difference between a hypothesis and a theory.

    Maybe a bit more generally than you’re asking, I would suggest that the thing most needed by the general audience is an understanding of the difference in philosophy that makes science different from religion. There are a lot of claims made by people in our world that are confused for scientific by laymen mainly because people don’t really understand the difference between something that “sounds” like science and something that _is_ science.

    There are a lot of cool things I’ve seen in my years of studying sciences, but weird, cool details are sort of lost on common people if they are just as weird and maybe less comprehendable in coolness than some internet inspired Hollyweird fantasy.

  • viggen

    Don’t get me wrong, Quantum in a nutshell would be cool too. And, if you can give me some hints about Renormalization group, it might help me on my homework;-)

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  • BoRon

    Space is expanding at an accelerating rate. Galaxies are accelerating away. Is this a coincident value or is the space imparting a force on the galaxies that accelerates them? Sounds like an ether is required.

  • Stray Cat

    That evolution does not assert that we evolved from modern day creatures, but instead that they are our distant cousins.

  • freelancer

    Can’t believe I’m the the first one here, but, f***ing magnets, they work how, exactly?

  • BoRon

    I observe an elliptical galaxy’s redshift. How do I differentiate redshift due to its motion, due to the stretching of space and due to its gravitation?
    (Sorry, that’s my 2nd and final question.)

  • Lin Mu

    With the coming climate circus in the congress. We need to know more about peer review, & how we know, what we know. We need clear unambiguous statements about how Science comes to consensus, and how it deals with junk.

  • Ben

    The spin 1/2 system in quantum mechanics. See Griffiths’ Introduction to QM, 2nd edition, Section 4.4, pg. 188-189.

    Since it’s a single particle, it’s easy enough to understand and to appreciate the weirdness resulting from the fact that Sx and Sz don’t commute.

  • Dan

    The general public needs to have an understanding that science is not out to (and usually cannot) PROVE things so much as to rigorously test hypotheses and see what stands up to these tests. I really think this is at the core of scientific illiteracy.

  • http://math-frolic.blogspot.com “Shecky R.”

    ditto Dan… public doesn’t understand there’s no such thing as ‘proof;’ only preponderance of evidence and hypothesis-testing…

  • http://evolvingthoughts.net John Wilkins

    The principle of least action. It underlies thermodynamics and pretty well every aspect of engineering, and yet some people seem to think that more can be done with less to any limit.

  • http://atouchofrant.wordpress.com Nick

    If we include principles from the practice of science, than echoing Dan and Shecky more on the standards of hypothesis testing that science adheres to, opposed to the more or less fallacious impressions about proof that tend to dominate popular (populist?) policy debates.

    If we’re just talking about scientific knowledge, I’d go with more on controlled fusion. ITER is about to get a huge chop to its funds, which won’t end well. But that’s just my own biases coming out.

  • takisword

    Thermodynamic laws (0-3)

  • http://duane-pwns.blogspot.com Duane

    Did you mean “at most” 140 characters?

  • AndrewL

    Gravity, No-one gets it.

  • CNR

    The scale of the universe.

    It’s simple, people can easily relate it to their experience and it gives people perspective.

    I think the major issue with the world today is that humans lack true perspective on reality. This allows things like myth, religion and pseudo-science to be called reality when they are obviously not.

    When you first learn that our galaxy is made up of billions of stars just like the sun and that the universe consists of over a billion, billion galaxies you begin to appreciate that we are not the center of the universe. That we are not “special”, but maybe just unique.

    When you understand this, our place in the universe and the implications it has on myth, religion, and pseudo-science (basically invalidating them), everything changes.

    Everyone needs to know this, because surprisingly enough, I think most, in fact a vast majority of humans, have no idea.

  • AJKamper

    Statistics and probability. Yes, it’s technically math, but it fundamentally affects not only science, but our entire understanding of how the world works, and people don’t understand these concepts at all.

  • Andrew Price


  • http://liveeverything.wordpress.com Meredith

    Uncertainty in measurements.The table is not “exactly” five feet wide – if you measured it again you might get a slightly different number, and that’s NOT because you suck at measuring or because the table (or ruler) changed size. Reality has error bars, and they are meaningful.

    Runner-up: the metric system. So that people know what a kilometer is in their gut like they know what a mile is. I still struggle with this, and I’ve been working in kilometers (okay, centimeters because I’m an astronomer and we’re partial to cgs) for years.

    I also wholeheartedly support the above “scale of the universe” idea.

  • Brian

    What the hell is the weak force? All the other forces transmit attraction (or repulsion) between other particles. But W and Z bosons seem to exist solely for the purposes of decaying into other things. Where is the force?

  • Navneeth

    I’m with viggen and Dan here. A lot of people first need to know what science is and how it is done before delving into any particular topic.

  • http://lablemming.blogspot.com/ Lab Lemming

    Statistical significance of potential trends in complex multivariate data.

  • Twilightened

    Quantum scale. What the hell is going on in there ?

  • Albert Bakker

    Many people tend to mention the one thing they themselves don’t really understand. If I did that I couldn’t limit myself to one thing, since I understand basically nothing. (And not even that.) But the question was what the one concept in science was that should be explained better to a wide audience.

    I think what Dan [#16] mentions is in the right direction. It is very important for every member of any advanced civilization to understand this concept properly. But there is a snag. You can expect at least one or several persons in a wide enough audience to come up with difficult questions about string theory (or other examples) : is it science or not? Do we have to admit that it is technically not science, but actually in some yet to be properly defined way it is? Or should we accept there to be a grey area between what is science and what is not science?

    If not careful this will take you right away to the intricacies of the demarcation problem and the philosophy of science and you probably don’t want to enter this terrain. But you probably don’t want to leave this problem entirely unanswered either.

    I’m with Dan, but I don’t envy the teacher.

  • http://dhyb.blogspot.com Andy Wood
  • Steve

    Renormilization group and effective qft. A good touchy feely description of how qft respects symmetries.

  • http://tetrahral.blogspot.com Steven Colyer

    Heisenberg’s Uncertainty Principle. Nothing makes more people quit Physics and Science in general than Indeterminacy taught poorly by Physics professors who lack educational skills, or disbelief in the subject itself, or worst, both.

    I’m not exactly sure what is the best way to teach this simple but vital concept, myself, but I’d suggest starting with the Mathematics of Inequalities, with the Cauchy–Bunyakovsky–Schwarz inequality, and move forward through Planck’s constant until you hit the year 1927 running!

    After that, Quantum Tunneling and Quantum Entanglement.

  • frances

    Black body radiation. But first, explaining how science works.

  • Quester

    That a negative result to a test is neither a failure of science, nor a waste of time, money or effort.

  • gaddeswarup

    Price Equation

  • Ijon Tichy

    Broadly speaking, I don’t think scientists need to do a better job explaining scientific concepts. I turn it around, and say that people need to do a better job *learning* scientific concepts. Too many lazy consumers sitting on their fat arses spending their time on mindless pursuits leads to an unhealthy society.

    That said, a few scientific concepts could be better explained. My favourite is “Olber’s paradox”, which is usually poorly or even incorrectly taught. See Harrison’s “Cosmology: The Science of the Universe” for a proper elucidation.

  • George

    Cognition, particularly the difference between what we think we know, and what we know, with attention to cognitive biases, particularly the power of anecdotal evidence, and the social and biological bases of learning. You can’t appreciate what you don’t know until you know why you don’t know it.

  • nobody

    The only thing we should explain better is the following:

    “Why should the public keep paying physicists and spending money on research.”

    Everything else (theories, models, data) is irrelevant (to the public).


  • http://www.droid-boy.de Droid Boy

    The concept of time.
    I have verry hard times to understand how that can change if you do stuff with lightspeed.

  • Pieter Kok

    That the universe and all its constituent parts are basically information processors, and that every process costs time and resources.

  • Mantis

    I think it is very important that the general public understands how scientific knowledge is established and in particular that scientific theories can vary greatly in their reliability.

    The credibility of scientific disciplines is derived from empirical evidence and empirical evidence only. Different scientific (sub)disciplines have very different access to empirical evidence and therefore their reliability also varies greatly.

    Those aspects of scientific knowledge which can be tested in cheap and easy to interpret scientific experiments/observations are extremely reliable. Those aspects which are gleaned from few indirect observations or a limited number of hard to control experiments are much more suspect and should not be relied upon too much. Finally theories supported by no empirical evidence at all are just pure speculation – completely unreliable.

    This is the reason why disciplines like classical physics or chemistry – already tested by countless scientists and engineers all over the world – are so much more reliable then social sciences where controlled experiments are very hard to perform and interpret.

  • Torbjörn Larsson, OM

    One thing: that a theory can be a testable fact (as in “evolution is both a fact and a theory”).

    the difference between a hypothesis and a theory.

    What is the difference aside from scale, pray tell? A theory, which is a conglomerate of hypotheses, can be as much ad hoc as an isolated hypothesis.

  • cynic

    how investment in basic research by taxpayers actual translates into jobs

  • Torbjörn Larsson, OM

    The fact that science asks “how?” rather than “why?” and therefore has no overlap with religion.

    So typical that the first comment on explaining science is a blatant religious agnostic claim which has absolutely nothing to do with science! Makes you sad for humanity.

    [It is elementary rejected too.

    For example, no zombies have ever been observed, nor believed to be possible for basic biological reasons. So no Jebus zombie. Thus Jebus religions goes against scientific fact.

    “No overlap”, indeed, such a silly claim, and you hear it from people who should know better.]

  • Thingy

    Gravity, Magnetism or Quantum entanglement – Those “at a distance”/”without a medium” subjects are what I find fascinating, and wish I understood more

  • http://romania-rocks.blogspot.com/ Mihaela

    The scientific method is on the top of my list

  • FamousRouse

    Truth matters !!!

  • thomas

    antennas are fuckin’ miracles. sure, it’s about waves in air resonating with waves in a material with different epsilon and mu, but like, if you’ve ever tried to design one, they’re incomprehensible.

  • thomas

    @steven coyler (38):

    The right way to teach uncertainty is to explain that the probability distributions of certain pairs of incompatible observables are related through a Fourier transform. Then, you can show them that the Fourier transform of a Gaussian distribution is a Gaussian distribution, and how the standard deviations of the variable and its transform are related. Simple, elegant, and points directly to the wave nature of quantum mechanics which you’re allso trying to convince your studence of.

  • Kevin

    It’s got to be a wider explanation of quantum physics and how it fits into the picture of how our world works..

  • apthorp

    1. potential energy.

    2. orthogonality

    3. conservation laws

    4. the math describes the world rather than the other way around.

  • Bill M


  • mike

    Faith in our senses and culture vs. faith in contingent scientific knowledge. For general audiences, how our senses are important, but can interfere with our ability to understand the world around us. Please help educate the general public about how understand and to value this discovery process and compare with other cultural and sensory knowledge systems. The fate of our species depends upon it.

  • http://gabeglopilot.com Gabe

    There is a general pop-meme that quantum science has discovered that underneath all this stuff (existence) is an infinite field of nothingness. I would be curious to know if this is in fact an actual finding or the result of pop-culture spin. I am in no way a scientist myself, but I love to know what is actual.

  • Anders

    I’d personally like to see an explenation of the things you talked about in the “space is not fundamental” presentation. It’s probably not a priority to teach that to the general public though :).

  • Anon

    Exponents. Size matters and people can’t get it.

  • http://www.savory.de/blog.htm Ole Phat Stu


  • http://sentioergosum.wordpress.com Daniel

    You should explain to yourself why you don’t have a clue. Please.

  • adequate

    The difference between life, consciousness and the universe. People seem to have a tendency to confuse those, for some reason.

  • Charlie C

    In this country, the problem is not just how to explain scientific concepts; foremost, it is to stop the media, parents, and schools from ridiculing science as boring, nerdy, and as requiring too much effort to educate our children to be competent in and even excel in. As other countries increasingly realize the urgency of a scientific education in order to compete for survival in this world, and as they reinforce the desirability of scientific knowledge by enthusiastically embracing it rather than dissing it in their popular cultures as we do, we continue to slide behind. Solving this will take a huge PR effort on the part of the government: stop smoking; eat healthy food; get enough exercise; learn how the world works. Or die. The scientific community must contribute by providing numerous simple examples explaining how the world works. This is not a trivial task: explaining how your iPhone works in accurate, clear language, even including, gasp, a little math requires taste, hard work, and even genius. In fact, many scientists would probably regard it as impossible. But we now have new tools for teaching and motivating that weren’t available even 10-20 years ago.

    So which “one” concept would best be explained? How about all of the suggestions above? Yes, you should select a few as a pilot project. But they should be tough ones, yet explained convincingly to primary school students and grandparents alike. Are we that good, or is it “too hard”?

  • Bruce

    The speed of light.

    How we measure it, what it tells us about the age of the universe, how light-speed is linked to and incorporated in technology all around us – like how cell phones and semiconductors actually work (scientific prediction, enabling things like precise matlab simulation of engineering design work, etc., versus random guesswork).

    Once people get that the speed of light is known, measurable and predictable – and that this knowledge is part of the reason we have things like cell phones, then it really put’s to bed the creationist notion that god created everything 6000 years ago. We wouldn’t be able to see the stars if that were true – let alone design cell phones. Once you dispel that 6000-year-old universe notion, maybe a few more folks would be a little bit more interested in learning some other areas of science.

  • SoundOff

    How something can be a wave and a particle at the same time.

  • StonedAgain

    Membrane Theory.

  • Dave

    Does it have to be a concept?

    How about, why we build and operate big, expensive colliders.

    I think people understand the purpose of a telescope or a spaceship. But all they hear about colliders is, “to look for a certain kind of particle”. Which I fear sounds like a terribly humble pursuit for such huge facilities and dollar figures.

    I’m only thinking about it because I live near Fermi, and I sometimes wonder about their financial future. :(

  • meit

    That you can’t really understand anything very well, until you do the math(atleast in the physical sciences).

    other than that: special relativity. at least at high school level. it can be done and in fact given its implications to our understanding of the world, it needs to be done. further, i think it’s the only accessible theory that shows how very counterintuitive science can be.

    also, evolution.

  • meit


    i agree with you. f****ing magnets.

  • denwoodm

    The limitations of studies (scientific or otherwise), statistics and polls.

  • hat_eater

    The scientific method. Most people have no idea how science progresses, or rather, they have a wrong one. Once you take it in, you sit up and start to pay attention.

  • abell

    voice through a copper wire; the door to science for non-scientists.

  • CNR

    Right behind scale of the universe I agree with:

    (12) and (68)

    Magnets freak me out. The repulsive part. I could play with a set of magnets all day by putting the like poles together and wondering how in the hell those things repel each other.

    (I mean, I have a pretty good feel for how, but the fact that the universe has that “how” as a property freaks me out).

  • ObsessiveMathsFreak


  • http://zombiebhp.deviantart.com Brian Phillips

    When describing the weak force, mass of bosons are used in mathematical calculations. A helpful method needed to depict the weak force could be some visualizations. Information of the nucleons is traded for information through the actions of the bosons. Consuming the data required to view these actions seems insurmountable.

    A graphic solution tells more of the story. Use of computers delivers what happens well enough to lessen the tension of exasperated minds.

  • ian

    That both directed and abstract scientific research are needed for society to advance. . . and putting more focus on research will lead to more advances. While this is obviously self-serving, it’s also a very under appreciated fact among the population at large.

    Quoting (National Energy Secretary and Nobel laureate) Steven Chu: “The federal government should be investing “tens of billions of dollars” annually to drive a Manhattan Project-style pace of innovation necessary to address the scale of the energy challenge facing the U.S.”

    If the US did this, it would certainly revolutionize energy technology.

    I don’t think there’s widespread opposition to this kind of a proposal, but there certainly isn’t widespread (and vocal) support.

  • Jordan


    Everyone reads them and, consciously or not, is affected by them. But they are rarely understood correctly.

  • http://www.scottaaronson.com Scott Aaronson

    The skill of sharpening a question to the point where it could actually have an answer.

  • http://opines.mythusmage.org Alan Kellogg

    Further to #22, how gravity works according to General Relativity. Physicists don’t understand this, or if they do, they don’t internalize it the way biologists have internalized evolution or geologists have internalized plate tectonics.

  • http://math-frolic.blogspot.com “Shecky R.”

    Age-old stumper: Where do socks go when you put them in the dryer???

  • Peter

    Ocean Tides! The moon doesn’t pull water away from the Earth! Everyone knows what tides are, but very, very few know how they work. Most physicists even explain this badly (ok my sample size is about two :) Why are tides difficult to understand – because they are complicated :)

  • Neil S.

    Conservation of Energy: under what conditions is it observed and how can a universe pop up out of “nothing” and not break it?

  • John

    Free will.

  • http://www.corticalhemandhaw.blogspot.com Brad

    The scientific method. Following that, evolution by natural selection, and following that, statistics.

  • http://tispaquin.blogspot.com Doug Watts

    Hmm … why pooping in your kitchen is not a good idea?

  • Michael Park

    Perturbative renormalization and the fact that it conceptually has nothing to do with the canceling of ultraviolet divergences should really be explained better.

  • George

    Another vote for basic statistics. Or even, just correlation vs causation.
    Likewise, the laws of thermodynamics.

    And magnets.

  • http://commons.bcit.ca/mylife/author/dmcgilvery/ C. Darcy McGilvery

    The benefits of extracting truth from reality via the scientific method, i.e., objectivity, discredited theories, critical thinking, open mindedness, etc.

  • Low Math, Meekly Interacting


  • http://yourbrainondrugs.net Caspar Addyman

    We are all terrible at predicting what makes us happy. Even professors of behavioural economics. So maybe happiness isn’t the goal of life.

  • a

    The answer, of course, is in the question. What should be explained is the “the concept of science” itself.

  • Shawn

    What is the arrow of time?

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  • http://moleseyhill.com mat roberts

    That “scientific proof” is an oxymoron.

  • http://www.astro.multivax.de:8000/helbig/helbig.html Phillip Helbig

    The opposite of comment #1.

  • chris y

    Why climate!=weather. If we get that one across we might be still in a position where all the rest (important as they are) can be dealt with.

  • http://gameswithwords.fieldofscience.com gameswithwords

    Hypotheses are testable.

  • Matt

    The curvature of space: every analogy we use is curving something from n dimensions into n+1 dimensional space. But apparently that’s not how it works.

  • Guillermo

    At the risk of giving a non-socially-charged answer…

    Gears. Like in cars and bikes. How shifting gears is helpful. I ‘understand’ the concept, but it took me a while and I’m not sure I have it right.

  • wildemar

    Hmm, didn’t really want to comment twice, but my comment (#1) seems to be misunderstood. Or not. So apparently my comment “should be explained better”.

    I’m tired of the whole “religion vs. science” debate. I want it to stop. Mainly because it’s unproductive (nay, counterproductive!) to do so, but also because it’s meaningless to begin with. Religions try to answer why we exist. And because most religions tend to precede scientific enlightenment, they also tend to include an account of “how”. It’s only natural to do so, given the absence of other (satisfactory) theories at the time. But that’s a side effect. The main reason why religion exists is to offer reliability, strength and a sense of community. None of which are objectives of science. So no overlap, at least fundamentally.

    If it matters: I’m a physicist and an agnostic. For all I care, people can believe in the flying spaghetti monster or the second coming of Newton. I’d just like everybody to drop the holier-than-thou attitude and stop wasting time on fruitless discussion.

  • Gammaburst

    Bell’s Theorem, Higg’s boson, Vacuum energy

  • http://www.catholiclab.net Ian

    @99, You appear to generalise ‘religion’. There are many religions, some of which do not encourage science, others do. Therefore my request would be that the meanings of ‘religion’ and ‘science’ are properly understood.

  • Ghost

    “Heisenberg’s Uncertainty Principle. Nothing makes more people quit Physics and Science in general than Indeterminacy taught poorly by Physics professors who lack educational skills, or disbelief in the subject itself, or worst, both.
    I’m not exactly sure what is the best way to teach this simple but vital concept, myself, but I’d suggest starting with the Mathematics of Inequalities, with the Cauchy–Bunyakovsky–Schwarz inequality, and move forward through Planck’s constant until you hit the year 1927 running!
    After that, Quantum Tunneling and Quantum Entanglement.”

    I don’t agree. Quantum mechanics is extremely well understood these days, but the way it is taught, by following the history, really obscures it. We don’t teach classical mechanics at the college level with the historical presentation, and quantum shouldn’t be taught that way either. Start with quantum information, axiomatically, entanglement, etc. Bam. Then do Hamiltonians and quantum dynamics.

  • oomkoos1

    1) SpaceTime – Once a student “gets it” a whole new world opens up.

    2) Probability – Many phenomena are not absolute but a continuum between 0 and 1. (Weather, Quantum Mechanics, Stock Market …)

    and let us drop this religion versus science talk. The bible cannot explain quantum mechanics and quantum mechanics cannot explain how to live in peace with your neighbor.

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  • meit

    Second law. That it is only a statistical law and not really a physical one. Specifically Loschmidt’s paradox. I mean, isn’t it the strangest thing, that the thermodynamic arrow of time is only a statistical arrow and not a direct implication of the physical laws as we know it(unless something ties it to the Big Bang)? I may be wrong here, but isn’t this a serious issue?

  • http://ckames@blogspot.com Charles Ames

    Demystify quantum mechanics. Bonus: The process of evolution. Most of us learn science blowing things up in chem lab, cutting apart frogs in biology, and sliding things around on ramps in physics class. But looking at what happens when you have lots and lots of things banging around for a long, long time might give more insight into things we encounter daily, like traffic jams and elections and economies and the weather.

  • Jim K.



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Cosmic Variance

Random samplings from a universe of ideas.

About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson. Here are some of his favorite blog posts, home page, and email: carroll [at] cosmicvariance.com .


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