Thought Experiments


The Particle at the End of the Universe: Why We Care

I was once interviewed by a local radio station about particle physics, gravitation, cosmology, things like that. It was 2005, the centenary of Albert Einstein’s “miraculous year” of 1905, in which he published a handful of papers that turned the world of physics on its head. I did my best to explain some of these abstract concepts, waving my hands up and down, which I can’t help but do even when I know I’m on the radio.

The interviewer seemed happy, but after we finished and he was packing up his recording gear, a lightbulb went off in his head. He asked if I would answer one more question. I said sure, and he once again deployed his microphone and headphones. The question was simple: “Why should anybody care?” None of this research is going to lead to a cure for cancer or a cheaper smartphone, after all.

The answer I came up with still makes sense to me: “When you’re six years old, everyone asks these questions. Why is the sky blue? Why do things fall down? Why are some things hot and others cold? How does it all work?” We don’t have to learn how to become interested in science—children are natural scientists. That innate curiosity is beaten out of us by years of schooling and the pressures of real life. We start caring about how to get a job, meet someone special, raise our own kids. We stop asking how the world works, and start asking how we can make it work for us. Later I found actual studies showing that kids love science up until the ages of ten to fourteen years old.

These days, after pursuing science seriously for more than four hundred years, we actually have quite a few answers to offer the six-year-old inside each of us. We know so much about the physical world that the unanswered questions are to be found in remote places and extreme environments. That’s physics, anyway; in fields like biology or neuroscience, we have no difficulty at all asking questions to which the answers are still elusive. But physics—at least the subfield of “elementary” physics, which looks for the basic building blocks of reality—has pushed the boundaries of understanding so far that we need to build giant accelerators and telescopes just to gather new data that won’t fit into our current theories.

Over and over again in the history of science, basic research—pursued just for the sake of curiosity, not for any immediate tangible benefit—has proven, almost despite itself, to lead to enormous tangible benefits. Way back in 1831, Michael Faraday, one of the founders of our modern understanding of electromagnetism, was asked by an inquiring politician about the usefulness of this newfangled “electricity” stuff. His apocryphal reply: “I know not, but I wager that one day your government will tax it.” (Evidence for this exchange is sketchy, but it’s a sufficiently good story that people keep repeating it.) A century later, some of the greatest minds in science were struggling with the new field of quantum mechanics, driven by a few puzzling experimental results that ended up overthrowing the basic foundations of all of physics. It was fairly abstract at the time, but subsequently led to transistors, lasers, superconductivity, light-emitting diodes, and everything we know about nuclear power (and nuclear weapons). Without this basic research, our world today would look like a completely different place.

Even general relativity, Einstein’s brilliant theory of space and time, turns out to have down-to-earth applications. If you’ve ever used a global positioning system (GPS) device to find directions somewhere, you’ve made use of general relativity. A GPS unit, which you might find in your cell phone or car navigation system, takes signals from a series of orbiting satellites and uses the precise timing of those signals to triangulate its way to a location here on the ground. But according to Einstein, clocks in orbit (and therefore in a weaker gravitational field) tick just a bit faster than those at sea level. A small effect, to be sure, but it builds up. If relativity weren’t taken into account, GPS signals would gradually drift away from being useful—over the course of just one day, your location would be off by a few miles.

But technological applications, while important, are ultimately not the point for me or any of the experimentalists who spend long hours building equipment and sifting through data. They’re great when they happen, and we won’t turn up our nose if someone uses the Higgs boson to find a cure for aging. But it’s not why we are looking for it. We’re looking because we are curious. The Higgs is the final piece to a puzzle we’ve been working on solving for an awful long time. Finding it is its own reward.

Excerpt from THE PARTICLE AT THE END OF THE UNIVERSE © 2012 by Sean Carroll. Published by Dutton, A Member of Penguin Group (USA) Inc. Excerpted with permission from the publisher. All Rights Reserved.

  • Anonymous

    Great answer!

  • Exactly right!

  • paigen

    I really enjoyed reading this. I can still remember being told as a child that I asked too many questions. Actually some people still say that about me today, but I can’t help it. There’s so much to know.

  • Planesman22

    Amazing answer. This is why we should never put down science and scientific research in general. Doing so will only delay our progression in human technology.

  • Anonymous

    Energy-Mass Poles Of the Universe

    Again and again:

    The universe is a two-poles entity, an all-mass and an
    all-energy poles.

    Singularity and the Big Bang MUST have happened with the
    smallest base universe particles, the gravitons, that MUST be both energy and
    mass, even if all of them are inert mass just one smallest fraction of a second
    at the pre-Bing Bang singularity. All mass formats evolve from gravitons that
    convert into energy i.e. escape their gravitons shatters-clusters, becoming mass formats in motion, i.e.
    energy. And they all end up again as mass in a repeat universal singularity.

    Universe expansion and re-contraction proceed

    Graviton is the elementary particle of the universe. The
    gravitons are compacted into the universal inert singularity mass only for the
    smallest fraction of a second, when all the gravitons of the universe are
    compacted together, inert, with zero distance between all of them. This state
    is feasible and mandated by their small
    size and by their hence weak force.

    The Big Bang is the shattering of the short-lived
    singularity mass into fragments that later became galactic clusters. This is
    inflation. The shattering is the start of movement of the shatters i.e. the
    start of reconversion of mass into energy, mass in motion. This
    reconversion proceeds at a constant rate since the big bang, since the
    annealing-tempering of singularity and the start of resolution of gravitons.
    The release of gravitons from their shatters-clusters proceeds at constant rate
    due to their weak specific force due to their small size.

    Gravity is propensity of energy reconversion to mass.

    Inflation and
    expansion are per Newton.

    Since the Big
    Bang galactic clusters are losing mass at constant rate. Mass, gravitons,
    continue escaping at constant rate from their Big Bang fragments-clusters thus
    becoming energy, mass in motion, thus thrusting the clusters. Constant thrust
    and decreasing galactic clusters weight accelerate the separation of clusters
    from each other. Plain common sense.

    A commonsensible
    conjecture is that the Universe Contraction is initiated following the
    Big-Bang event, as released moving gravitons (energy) deliver their thrust to
    other particles and are collected by and stored in black holes at very low
    energy levels steadily leading to the re-formation of the Universe Singularity,
    simultaneously with expansion, i.e. that universal expansion and
    contraction are going on simultaneously.

    The conjectured
    implications is that the Universe is a product of A Single Universal Black Hole
    with an extremely brief singularity of ALL the gravitons of the universe, which
    is feasible and possible and mandated because gravitation is a very weak force
    due to the small size of the gravitons, the primal mass-energy particles of the

    Dov Henis
    (comments from 22nd century)

  • Well, it’s well written. That’s a plus.

  • Profound thanks from a grandma of 2 small boys with lots of questions! Curiosity is everything!

  • Nicholas Dunbar

    Imagine if you told a cow you were using grass to accelerate particles, she would think you were crazy. Fortunately, we are not cows and their is more to life than grass.

  • Warren Peace

    Please -“The Higgs is the final piece to a puzzle we’ve been working on solving for an awful long time.” FINAL Piece? A boson is one of a suite of gauge bosons, and given our math, statements like “the theory of everything” (TOE), or “God Particle”, simply demonstrate the egoism of under-appreciated physicists. Because the math used to model the universe require several results like ˚∞” (infinity), and functions like division, so the truth is, we will never find a fundamental particle for the simple reason that it is not there (even if a Higgs, IS. Cantor may have proved the countable infinite, but I dare you to!!) – just keep building higher-energy machines, looking for smaller slices of infinite.

    I think it would be better for all the scientists, philosophers, and truth-seekers to take a century off to contemplate these two truths (or can there only be one?):

    1. From nothing comes everything

    2. The universe (multiverse.. whatever) was never created – it has been, and always will be.

    Of course, if you find that it equals 42, I’m packing my towel for Betelgeuse!

  • Paul Halpern

    Excellent piece!

  • I do not understand where we are in terms of the CMB. Are we looking at the universe as it expanded from inflation, and are we outside looking back at it? Why cant we see into it? Is anything being worked on to see inside this stupid roadblock? Also, what really has got me thinking lately, Do we have anyone working on particle wave duality? I’m with Einstein, I believe the moon is there when I’m not looking at it….

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  • Giuseppe Lacagnina

    I certainly agree. First of all, I believe that curiosity is the mother of all science. Not to mention the fact that without pure research nowadays we would not have computers or airplanes and we would not know about bacteria and viruses. What is commonly accepted today was a revolution at some point in the past. Let us not be short-sighted. (

  • I enjoyed your comments and it is one that is currently interesting to me. I have recently got a local realistic reconciliation of the EPR paradox. I hope to get it to press within a short time, but I have worked on this for 16 years so it is time for publishing. My solution is purely quantum and a computer program simulates the EPR correlation with this local realistic spin model and violates Bell’s inequalities.

    Now to do this my spin model has two axes of quantization rather than one. Without details, it turns out that with two axes everything falls into place and makes perfect sense, but it can never be experimentally verified. That is, you can assume quantum mechanics is complete, and accept non-locality and indeterminism, or you can assume two axes and get a local realistic solution.

    So if this is all right, then, as the reporter asked, who cares?, especially if you cannot experimentally prove one way of the other.

    The answer is given in this blog, we want to know the truth. Choosing local reality requires a paradigm shift, and such changes are slow. However if local reality is accepted, finally, and the vast majority of physicists would prefer that to non-locality, then the way we think and view Nature will change for the better. We will understand how local reality leads to quantum waves and we will have to change how we view entanglement and the statistical nature of quantum mechanics. I believe it will cause people to think again how quantum information works, like teleportation (which cannot happen in my theory). Also all elementary particles in the standard model, except the Higgs boson, have non zero spin. So I think viewing spin as with two axes will have a profound influence on our thinking of elementary particles.

    I put a lot of this stuff in my blog:

    hope you can have a look.

  • Bardia Hafizi

    As the great man said: “sure, it may give some practical results, but that’s not why we do it.”

  • Dimitris Babul

    Dear Sean, you are right. If we do not find a divice through physic to work against gravity and a multiple wave / field engineering for workinf with materials, man kind will never get a real quamtum leap of energy eficiency, more over thinking on the physical math of wormholes trough time – space, is critical, because at some point of the life of our planet, we will need de move millions of persons to new locations in a better and more efficiente way that now. According to this, breaking Gravity law at the lower posible cost, working with material under their real origing that is waves and fields will reduce costs and build up efiency , finally wormholes will save our civilization. Physics matters, more that ever for the big quantum leap on sustainable innovation, techonology and engineering for the future of our planet. Fusion, better that fision, is the futute energy based on hydrogen. Thanks for the article.