Thought Experiments


Welcome to The Nature of Reality

When I was seven, I understood relativity perfectly. I got it. At least I thought I did. And it was glorious.

It all started with The Flight of the Navigator, that movie about the kid who accidentally stumbles upon a space ship and has a grand old afternoon traversing the galaxy in the company of its cargo of friendly creatures. The problem? When he returns to Earth he finds that eight years have elapsed. He has been declared missing; when he rings the bell at his old house, a stranger answers the door.

The Flight of the Navigator is a story about time dilation. The ship was traveling close to the speed of light, so time passed significantly more slowly for its passengers than it did for those back on Earth. That’s special relativity for you. It seemed easy, elegant, amazing.

For the next few years, that was my relationship with relativity. Then came the equations, and suddenly relatively didn’t seem so easy any more. Elegant, maybe. But that first spark of intuition got lost in symbols, equations, calculations and miscalculations. So I wondered: Why can’t we have it both ways? Is it possible to be both wide-eyed and rigorous, methodical and amazed?

That’s a balance even physicists struggle with. As MIT theorist Max Tegmark told NOVA, “When I was in high school, physics was my most boring subject….It was only later that I realized that physics isn’t at all about just solving some equations. It’s about figuring out what reality is all about.”

That’s what we’re doing on this blog: taking on the biggest questions of all, the ones that get at the very nature of reality. What happens to information inside a black hole? What are we really talking about when we talk about teleportation? What if the laws of physics can’t be unified? Every week, we’ll have a new post from a scientist or science writer–look for James Stein, Sean Carroll, and Frank Wilczek in the coming weeks and months–with plenty of room for you to join the discussion with your own questions and ideas.

We hope you’ll let us know what subjects in fundamental physics you want to hear about—the stranger, the better. Can neutrinos really go faster than the speed of light? What is this spacetime thing anyway? Is our universe just one of countless others in a multiverse? Join us as we dive deep and discover how physics is changing what we thought we knew about the nature of reality.

Tell us what you think on Twitter, Facebook, or email.

Kate Becker

    Kate Becker is the editor of The Nature of Reality, where it is her mission to blow your mind with physics. Kate studied physics at Oberlin College and astronomy at Cornell University, and spent seven years as senior researcher for NOVA and NOVA scienceNOW. Follow her on Twitter and Facebook.

    • Anonymous

      Since this is ‘Thought Experiments’, this is one that has floated around in my head for some time.

      In quantum physics, isn’t it possible (as opposed to probable) that since virtually anything can come about with the random coming together of particles of matter and energies that a creature/being that we humans could only describe as omnipotent/omniscient just ‘happen’ from all of that chaos?

      I think that thought first came to me in the 80’s after reading an essay by Isaac Asimov about quantum physics where he said, simply, that quantum physics dictates that from absolute nothing ‘must’ come something.

      • Schroee1

        Are you talking about the probability of God (or “A” god if you are an atheist)? If so, I’m going to have to think about that one. Thanks for keeping me up nights.

        PS…Love the name

      • Intelligentbelief

        Very interesting – that an Omnipresent being was created from the Chaos… I am a ‘nontraditional’ college student and long time thinker and rebel of accepting any kind of proposed explanations for our existence, the existence or acceptance of existence of God with a pretty deep-seated willingness to accept that there are things I just don’t know and never will understand.
        With that said; I came to a solid belief in God four years ago… and through my studies in Anatomy and Physiology and this semester, introduction Chemistry, I become more convinced that the creation of life and the cosmos and environment to support it could not have been random. That a microscopic cell could have 20+ components that all must work in harmony to sustain life and create new life cannot be random… that the nucleus of that cell contains instructions for the organism it inhabits and sustains is nothing short of miraculous.. that translation and transcription does take place billions of times without an error.. and even sometimes intelligently to adapt to changes in the existing environment, is beyond comprehension.
        That, as described a change in Hydrogen ‘something’ by a tenth of a % would create an environment incompatible to life …. wow!
        There is a God…. this is the proof 🙂

        • Jeff Michals-Brown

          The idea that the universe is somehow fundamentally “tuned” to allow our existence (and the efficiency of fusion isn’t nearly the half of it) really bugs many astrophysicists, since it’s one of the few areas of nature that we don’t have a good, well-established natural explanation for. All the other ways we thought we were “special”–everything orbits the sun, our sun is the center of everything, humans are specially created, etc.–have fallen with time. This one, the so-called “Anthropic Principle,” is so far answered only by the hypothesis that we are only one of many universes (the “multiverse”), which has as yet no hard evidence to back it up.

          • Dslaby

            It’s not that the universe is finely-tuned for human life, but that human life evolved through a long history of trial and error to survive in the universe.

        • Dslaby

          This process gives up an infinite number of gods; what would their function be? We would revert to animism in which each conceptual item in the universe would have a god. The problem of infinite progression, or infinite regression, brings us to the problem is whether the universe is continuous or discrete.

    • Theothersteven

      If space itself is expanding, and the Earth (and us) are part of space, why are we not expanding as well?

      • You answered your own question! It is space that is expanding, not matter.

    • Dansteinbrenner

      all of our perception is subjective. only a glimmer of a memory from when all things past, present, and future were unified. now.

    • ResearcherTony

      A super show would have all the shock and awe you could ever ask for.
      What if all reality is artificial- intelligently made. Life is not really living / alive. Natural is not really natural at all – just Bio-technology illusions of an arterial realities made to “look as” really hurt you brain cells badly.

      What a gas, if we were all fooled into thinking all this is “reality”, yet it never was, just made to look like it is. A reality that is impossible to really exist, yet it does, but artificially.
      If the universe is an artificial creation – would that false reality – that artificial / illusion of what nature

      That man is a “show” with brain power – shock and awe to the extreme.


    • ResearcherTony

      Just as “history” is whatever the winners of warfare choose to make it (written records). So to a Creative intelligent mind would choose to create “reality” in whatever way he wishes too. To create something that cannot exist or would not normally exist, but try to fake it anyway by creating an illusion that would past for the real thing to simple minds like us.
      Is not life a fake – an illusion of living matter that cannot really exist, a “reality” that in physics is really impossible to have? Are we not the best of fools – living in an artificial reality?

      • Joultimo

        It’s illusion from the perspective that if you take the quantum multidimensional universe as a whole, it is a static system of infinite expressions, so any individual identification with a single expression is an illusion. If our self of another dimension made the opposite choice as our self, we have the same person living completely different experiences. To both selves, individual existstance (identity) would appear relative to the choices they have made over the course of their lives, but this identity is false. The self cannot be the human baby that grows into adulthood, but must be the mind that enhabits the human. This mind at a subtle leve lays a course for what we call our lives and theinfinite of potentials collapses into our experienced reality. How can we ever really be a single potential of a multidimensional static universe. The multidimensional universe is static because all potentials are and always will be finite. All potentials that exist for any possible potential exist in a static form, only when a consciousness, or perceiver, is made self aware within a single timeline of their life, is the static perceived as motion. We perceive motion within a static multidimensional world because our consciousness is bound to the perception of the world around us. This manifests as the progression of our life and the laws which we experience about the physical world. We are a single appearance of an infinitude of possible appearances, in Buddhism, this is the nature of our, the minds, prison. We are mind that is one with all infinite potentials, yet we exist in our own experience as mind living out as a single potential. Our experiences are relative to the nature of our mind.

        • Dslaby

          Neurobiology resolves the mind-body dualism by mind being a manifestation of the patterns of neural connectivity. Dead brain no mind.

    • ResearcherTony

      The greatest paradox of the human existence might turn out to be our false / illusion of what realities is. If we were created, yes programmed to believe this reality is real – but is not in fact. What if scientific research showed clearly that what is real is counter-intuitive, and living matter is just bio-mechanical.

      The paradox of mind and emotion (reprogramming to think what is real/ reality) and the counter evidence of quantum physics that to us could not be “true” because it conflicts with our pre-programming ideas on realities.
      Science would be restricted from moving forward it we could not “think” beyond our set programming, always stuck in a restricted mind loop- preset by someone else behind the veil of realities.
      In talking to everyday people, it is clear that our feelings can and do stop us from understanding the true nature of realities (physics).

    • gez1289

      a few things make me wonder,one is if there is much hydrogen on Jupiter,then why when the comet hit it ,it didn’t start hydrogen fusion to start?

      • Schroee1

        No helio-spherical pressure….if you leave room for the atoms to get out of the way, they will…rather than fuze

    • gez1289

      when iron is in a melted state it has no magnetism ,but yet they say the melted iron core of the earth produces our magnetos sphere?

    • Jonathandaubin

      thank you.

    • What would it mean for us if the laws of physics were unified?

    • veritas

      I have to wonder, particle physics is getting more and more complicated and problematic and the solutions more and more convoluted. It’s like the time when people were trying to explain why the then known universe revolved around the Earth.
      Eventually G. came up with a whole new theory and bang, the old ideas went down the drain.
      So it will be with subatomic physics, that’s my guess.

    • antonio carlos motta

      i think as is wonderful our mind by capture quantic processes,in theirs more deep mechanism,as nonlocal processes,or nature of the spacetime explained by connections of particles,it is as our mind process to causal level the
      quantic connections that does link future and past,ot place us as observer
      that altere through of ours neuronal mechanisms our interpretations of effect and cause chains.the future so as the past are occuring simultaneously,and the variables are whether alterning ,in past and future to differebnt observers seeing the same phenomenon.the nonlocal coonections betwen particles can to be seen separately or at the same same time by one same observers,the
      particles in spacetime can be acting as particles or antiparticles depending of the deslocatation of the observer in relation to the forward or backward in the time,as stuckelberg-feynman dyagram.then the spacetime can to be derivedof the perception of observers and the phenomenon observed.
      then the “particles ” are sensations produced by quantum world to our consciouness.then each “particles” vibrate in onr only one frequency.this each particles have an only one spacetime continuos,generated by particles if reversing in the spacetime in antiparticles and viceversa,by spinorial rotations.
      then the connections of particles and antiparticles going and coming in the
      spacetime are generated by vibrations in strings that has its ressonabces
      theirs only one harmonics.then the speed of light is graded in each spacetime continuos-see lie’d graded algebras with propeties anticommutative and some nonassociative when does occur the violation of the opperator that generate the infinities spacetimes as infinity vectorial space.-it is the manifolds with complex strucures as universe in 11 or 12-dimension( the time is segmented with double orientations)
      antonio carlos motta

    • Mott Phys

      i think that THE STR place us a reflection about connection of space and time,and speed of light as someone absolute in the universe,and theirs relations with the connection of space and time in an only one entity ot spacetime continuos in 4-dimensions,with double fold,left-right handed or rotational spacetime with left-right handed spinors-clifford’s algebras.then the multiverses are possibles when try unify the str and quantum mechanics.
      then neutrinos and antineutrinos breakings theirs helicities,travelling faster than speed of light is necessary.thence generating violations between particles and antiparticles( CP.PT),but conserving the CP in strong interactions.
      i think that the antiparticles do not exist,and its are subproducts of the
      violations of PT;this is due the relativistics variations that occur in highly speeds near the speed of light to our spacetime geometry or curvatures of spacetime,where in 4-dimensions appear smooth totally manifolds.
      the time dilatation and contraction of spacetime are products of the variations of the left-right handed spins( rotationS).thence the differences of velocities are seen as variiations in the curves of spacetime.

    • Mott Phys

      i think that the fundamental in the universe are not “points” “and” ticks” for space-time continuos,that has simultaneiuly a strucutre continue and discrete;this is these entities are biquaternions or matrices irs operations generates the spacetime discrtes and continues.being so the spacetime is completely abstraxts.the spins are the coordinates of spacetime in rotations,where these sistems rotyational are not invariants;but cpt is conserved by left-right handed rotations systems that if exchange one into others.
      the particles and antiparticles if cancel in the spacetime through the time dilatation and contraction of the twin paradox of twins,the twin traveling near the speed of light thhe time goes if dilating,but when return for earth the time going backward as positrons goes canceling the difference of time and space between the spaceships and the the observer in earth.
      and the twin return with the same time that her brother.then electron and positrons go if canceling.then the spacetime in the differents speeds go
      if canceling.
      therefor do not twin paradox.the that occur are differents mark the curvatures of spacetime,through of wavesfunctions traveling from the “past” to “future”
      and other travelling from the “future” to “past” given by spins.
      then the spáce and time go if nulling in all the “points” and “ticks”.
      then the the spacetime are variavel discrete and continue forms
      then the spacetime are wavefunctions operated by matricial systems in 8-dimensions with background by noncommutative topology and geometry

    • Kate Becker’s post is a good reminder that there is still a lot more to know about the unknown and even about what we do know today – which may have to be ‘re-known’ in future inquiry. We’re not done yet (far from it).

    • Hakuin Suso

      To speak of the nature of Reality you have to define what you mean by “Reality”. Ms. Becker does this only in a round about way by referring to questions and problems in physics. However, physics is a science with it’s on particular philosophy and parameters of study that are not all-inclusive.

      The most obvious subject omitted from physics is consciousness, even though it appears consciousness is necessary to determine whether Schrödinger’s cat lives or dies. Yet most physicists ignore the question of consciousness. In so doing, they limit their understanding of the universe and their place in it. So can we really count on physics to give us a full and final explanation of what reality is? Can physicists really tell us what reality is when the most basic element that we all have in common, the one thing that we all know immediately, i.e., consciousness, is ignored?

    • Dslaby

      The question of the multi-verse needs to consider the Theory of Evolution based on adaptation – There are a potentially a greater variety of life forms than actually exist based on DNA. There are potentially a greater variety of universes than actually exist based on string theory. Existing life forms are those which have descended (or ascended) from ancestors through the process of natural selection and exist in adaptation with current environmental conditions. Of all universes, may ours exist because it is adaptive to the conditions necessary in the HIGGS field? There may be a principle of self-organization at work. Like biological evolution that produces more diversity than survives, the evolution of the HIGGS field may produce more universes than survives, perhaps because the one we currently live in has the right combination of constants to enable self-organization and has the competitive advantage for existence.

    • thenewgreen

      More on the Higgs hunt please. Also, come by and visit us at Hubski. Physicists are always welcome! Here’s a link to our physics tag (one of our most popular)

      • Mott Phys

        doesn’t exist the boson of higgs,maybe there is several bosond of higgs

    • Jeff

      Naturally, people with the power to define your reality, are the ones who will steer your destiny. But then again, those people with power, are controlled by unknown forces of nature, and thus, can do nothing about it.

      The knowledge of people is infinite. So, then there will be no definitive reality.
      Such as the infinitely outward and infinitely inward nature of matter.

      • Mott Phys

        the matter and energy are generated by tension of superstrings that produce infinities osccilations with infinities numers of harmonics depending the strain produced in the superstrings,that generate and are generated by multiples dimensions-that are the topological quantum field theory-the universe are holograms of the CFT and the desitte universe.
        then the that observe is of that could “see” ( consciouness) the that happen in the intervals of spacetime that could observe in given instant”
        or “place”

    • d_cisz

      “OK, so what’s the speed of dark?” –Steven Wright

    • John Venrick

      the universe is not expanding or shrinking, it is infinite and we are just here for a very short time needing something to talk about

      • Dslaby

        I believe that the steady-state model of the universe does not fit the empirical evidence.

    • Jeff

      I, like physicists recently, have to smash things up to find out what makes them work.

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