Chapter 2

Section 1: Rethinking Space and Time Again

“We are so locked into the world of our own senses that, although we readily under­stand and fear a loss of vision, we cannot con­jure a pic­ture of a visual world beyond our own. It is hum­bling to realize that evo­lu­tionary per­fec­tion is a will-o’-the-wisp and that the world is not quite what we imagine it to be when we mea­sure it through a lens of human self‑importance.”

Timothy H. Goldsmith

“What is essen­tial is invis­ible to the eye.”

Antoine de Saint-Exupéry

Neutral Buoyancy Laboratory, NASA’s Johnson Space Center, Houston, Texas.

I am drifting-floating just inches above the daz­zling white sur­face of the International Space Station (ISS). This bril­liant play­ground calls to me, con­necting me to a sen­sa­tion dis­cov­ered during child­hood after building my first fort – a place where I could keep my top-secret projects safe, a place where I could observe the rest of the world as an out­sider. Simply being here dilates my nerve end­ings and heightens my senses. In the back­ground there are invis­ible eddies of resis­tance and my skin tin­gles with a con­stant stir. As I look at the struc­ture before me it is impos­sible to tell whether I am moving or it is moving. All that exists of the motion between us is rela­tional, no other meaning sur­vives. Another yellow handle comes within reach. I extend my hand and gently tug on it to redi­rect my course. I can feel the bil­lowing cylinder rotate beneath me right on cue. I have to remind myself to breathe.

I con­tinue gliding slowly from one handle to the next as if I were playing out the stanza of an elo­quent sym­phony. Arm over arm I move over this sur­face as the music in my head builds toward its apogee. Although I am watching this space ship move beneath me, I sus­pect that an onlooker would describe me as a small bug encir­cling the branch of a tree. That is, if they allowed them­selves to com­pare one of history’s most impres­sive con­struc­tion projects to the branch of a tree.

In the middle of this stanza I hear the crackly voices of Mission Control over my bone phone. They are detailing the Orbital Replacement Unit (ORU) pro­ce­dure as the Mission Specialists make their way from the Pressurized Mating Adapter (PMA). One of those astro­nauts is my dive partner’s father.

After com­pleting our NASA nitrox cer­ti­fi­ca­tion, Brad and I under­take our first mis­sion. My beating heart is con­stantly expressing how big of a deal this is to me. Even access to the deck above is tightly restricted, but now, as offi­cial flight leads, we are floating with astro­nauts around the ISS with a project of our own. The sen­sa­tion is exhilarating.

This expe­ri­ence took place inside the world’s largest indoor pool (202 feet long, 101 feet wide, and 40 feet deep) known as the Neutral Buoyancy Laboratory (NBL). It is a satel­lite to NASA’s Johnson Space Center (JSC) in Houston, Texas. The pool har­bors exact scale mock-ups of the ISS, the Hubble Space Telescope (HST), and the Space Shuttle Cargo Bay, which are used to sim­u­late mis­sion EVA’s (Extra Vehicular Activities or ‘space walks’).

When the NBL was orig­i­nally built, NASA had some dif­fi­cul­ties procuring the appro­priate water allo­ca­tions for it. Consequently, it took over a month to fill the pool using only a garden hose. Now the entire volume, along with its care­fully bal­anced chem­i­cals, is fil­tered every twenty-four hours.

As the astro­nauts con­tinue their sim­u­la­tion Brad and I begin our task. Our ‘cow­boying around’ — which is what it is called when an EVA is per­formed without a tether — is not just an attempt to ful­fill a child­hood dream; we are pho­tographing sev­eral of the external ISS com­po­nents and its gen­eral pro­file for a cat­a­logue we are com­posing. The ISS is recon­fig­ured daily to repli­cate the stage of con­struc­tion that each sim­u­la­tion crew will encounter in space. Photos of the inter­me­diate stages will be a useful ref­er­ence. Volunteering for this task gave us a good excuse to get into the pool every day.

I am car­rying a bulky under­water dig­ital camera and snap­ping pic­tures of this inspi­ra­tional behe­moth as it floats beneath/above me. When the memory card is almost sat­u­rated I hand the camera to Brad and begin to explore. It takes sur­pris­ingly little imag­i­na­tion to pre­tend that I am actu­ally in space. Everything is neu­trally buoyant — just floating about. The Cargo Bay of the Space Shuttle is vis­ible off in the dis­tance, and when the con­ver­sa­tions with Mission Control cease, an eerie silence sur­rounds me. The colors are dif­ferent too – not quite like they would be in space, but dif­ferent enough to spark a feeling of the unfa­miliar. It is a feeling that pours over my body and passes right through me.

Suddenly I recall my dreams of being in space and I am over­come with the desire to dis­cover what if feels like to be drifting off into the heavens without the pos­si­bility of retrieval. Knowing that I am not wearing a tether (and allowing myself to believe that I am in space instead of a pool), I grip another pro­truding yellow handle and accel­erate toward the edge of the cylin­drical lab­o­ra­tory. I see the mas­sive struc­ture move beneath me. Handle to handle I pull and push. Then, as I launch off the edge of the struc­ture, I turn and watch home base drift fur­ther and fur­ther away.

That’s when it hit me. That’s when I really fig­ured out what it means to say that velocity is entirely rela­tional. I had expected to expe­ri­ence what it was like to be drifting away from the ISS to my inevitable end, but instead I wit­nessed the ISS drifting away from me. This was some­what sur­prising. For some reason, every time I had imag­ined what this expe­ri­ence would be like I had visu­al­ized it from the ref­er­ence frame of the ISS. Now I was seeing it through my own eyes — from my own ref­er­ence frame. The expe­ri­ence deeply rooted my intu­ition in the foun­da­tional prin­ciple in physics that tells us that all iner­tial frames are on equal footing — that one con­stant velocity ref­er­ence frame is just as valid as any other.

Galileo Galilei con­nected to this prin­ciple inside the cabin of a ship.[1] Einstein used the train sta­tion in Bern, Switzerland to relate his con­nec­tion to it. I had learned from their insights and had com­pletely accepted the prin­ciple of iner­tial frames as a fun­da­mental truth. But until I actu­ally saw the ISS drift beyond my reach, my intu­ition had not absorbed it. I had not grasped the enigmas that come with this truth. I had not wres­tled with the mys­teries that sur­round this simple prop­erty of space­time. I had never asked why it is that all iner­tial frames are equal. This simple ques­tion turns out to be a very profound.

The greatest mys­teries of the phys­ical realm are but echoes of our igno­rance of space and time. Although they underlie all of our expe­ri­ences and form the very metric of Nature, space and time have remained so clan­des­tine that we haven’t even been able to defin­i­tively define them. This neb­u­lous under­standing will no longer do.

It is time for us to crown our search for a deeper essence, to open the doors of a won­drous world that is acces­sible to us only by the power of sci­en­tific imag­i­na­tion, to learn to see what is invis­ible to the eye. In order to do this we must focus in on the very core of our igno­rance. We must rec­og­nize the root of our con­fu­sion and wrestle with ques­tions that reflect that root.

This is not an easy thing to do; in fact, it is extremely dif­fi­cult. The bril­liant physi­cist Kip Thorne pon­dered this problem and was able to use a superb example of why it is so dif­fi­cult for us. He notes that Hendrik Lorentz and Henri Poincare both pro­duced valu­able insights that could have easily led them to dis­cover Einstein’s new vision, but nei­ther of them took that final step. Why? The answer, according to Thorne, is that both men “were groping toward the same revi­sion of our notions of space and time as Einstein, but they were groping through a fog of mis­con­cep­tions foisted on them by Newtonian physics.”

Einstein by con­trast was able to cast off Newtonian mis­con­cep­tions. His will­ing­ness to start his inves­ti­ga­tion from scratch, whether or not it meant destroying the foun­da­tions of Newtonian physics, “led him, with a clarity of thought that others could not match, to his new descrip­tion of space and time.” [2]

The lesson here is that if we are serious about ques­tioning things, we need to ques­tion even the struc­tural foun­da­tions that lie under­neath our assump­tions. We need to be willing to rebuild the entire metric of phys­ical reality — should our inves­ti­ga­tion require it. Only then can we reach into the depths of our igno­rance. Only from this state of mind can we truly ini­tiate a new journey.

In this spirit, let’s ask the most foun­da­tional ques­tions we can – ques­tions about the metric of space­time. What is space? What is time? These ques­tions appear to be entirely embry­onic, and it seems that the answers should be readily evi­dent, but they aren’t. Hypothetical solu­tions to these ques­tions have come to rep­re­sent the cen­ter­pieces of a realm still beyond our expe­ri­ence and imag­i­na­tion. Many believe that in order to dis­cover that realm it is crit­ical for us to resolve the debate over the essence of space and time. Should we accom­plish this, we will surely open a new door for the journey that has shaped our intel­lec­tual history.

Newton, who was one of the most influ­en­tial cap­tains on this quest, spear­headed our journey under the direc­tion that space and time are real – that they are phys­ical enti­ties. But after Newton retired his com­mand, Mach reversed our course by insisting that space and time aren’t real phys­ical enti­ties at all. Later, Einstein redi­rected us to an entirely new heading by redefining what we mean by space and time. Under this new direc­tion we entered waters that had never before been charted. For a while, the dream of dis­cov­ering a richer map filled our sails. But this opti­mism didn’t last for long. After a few short years Einstein reluc­tantly relin­quished his com­mand to the tyran­nical whims of quantum mechanics. From that point on we have been ran­domly changing course, nau­seously flick­ering from one heading to the next with each new moment.

The wind still blows but our sails rarely cap­ture it. It has become increas­ingly obvious that we are lost in the middle of a dis­ori­enting ocean, spin­ning about a heavy anchor.

It is time for us to lift that anchor. It is time for us to re-establish a heading on our intel­lec­tual quest, and to use our full sail to propel us toward our trea­sured des­ti­na­tion. In order to do this, we need to figure out where we are and how we got here. We need to trace out the ideas that have guided us to this point, and then we need to find out what assump­tions those ideas are based upon. After we have done this, we will con­cern our­selves with finding a way to over­come the lim­i­ta­tions inherent in the maps that fall out of those assump­tions. It is by this process that we will learn how to pick a new direc­tion, trim our sails, and recap­ture the wind. Here we go.