The Un­known Un­knowns

Science Illustrated - - EDITORIAL - An­thony Ford­ham aford­ham@next­

Dur­ing the pro­duc­tion of this edi­tion of Aus­tralian Science Il­lus­trated, I got into a de­bate on Quora (the web­site where you ask ques­tions and then get an­swered hope­fully by peo­ple with some ac­tual knowl­edge of the sub­ject) with a man who in­sisted that hu­mans would never never EVER never achieve in­ter­stel­lar space­flight.

In­ter­plan­e­tary is no prob­lem - he seemed happy to ac­cept that we would ul­ti­mately colonise the en­tire so­lar sys­tem. But go on from there to Al­pha Cen­tauri? No chance.

His ar­gu­ment, broadly, is that no ob­jects in na­ture rou­tinely travel in­ter­stel­lar dis­tances. This is di er­ent to our other achieve­ments. Flight, you see, was ob­vi­ously pos­si­ble be­cause birds fly. Very fast land speeds us­ing some kind of ma­chine was ob­vi­ously pos­si­ble, be­cause stronger, more-spe­cialised an­i­mals run faster. In more re­cent times, our ob­ser­va­tions of var­i­ous at­mo­spheric e ects show that su­personic ve­loc­i­ties are phys­i­cally achiev­able, and nat­u­rally-oc­cur­ring iso­topes of Ura­nium re­veal the se­crets of nu­clear power.

In other words, this man claimed, ev­ery­thing hu­mans have ac­tu­ally achieved was done first, in some way, by na­ture. And there’s noth­ing in na­ture that flies from star to star. Of course, he means there’s noth­ing we

know of, noth­ing we’ve yet ob­served do­ing this. That doesn’t mean noth­ing does. In fact some things def­i­nitely do, such as so-called rogue plan­ets that have been grav­i­ta­tion­ally ejected from their orig­i­nal sys­tems.

(As for this whole idea of us only copy­ing na­ture, I per­son­ally can­not name the species of bird that flies to the moon, or the natural oc­cur­rence of a nu­clear fu­sion re­ac­tion main­tained by a ”mag­netic bot­tle” rather than the in­tense grav­i­ta­tional pres­sures at the heart of a star. Or an or­gan­ism that com­mu­ni­cates across the en­tire planet at near-light-speed by ma­nip­u­lat­ing streams of elec­trons and pho­tons.) The other big prob­lem with my Quora friend’s ar­gu­ment was that he as­sumes that physics is al­ready com­pletely un­der­stood, in a fun­da­men­tal way. He as­sumes we will never ex­pe­ri­ence an­other rev­o­lu­tion of thought sim­i­lar to Rel­a­tiv­ity. We will never learn to look at the build­ing blocks of the uni­verse in a di er­ent way to quan­tum the­ory. Pre­sum­ably, he be­lieves quan­tum the­ory and the stan­dard model will never be united. Grav­ity, which we cur­rently do not un­der­stand very fun­da­men­tally at all, will never be fully de­scribed.

This seems like a fairly dan­ger­ous pre­dic­tion to make. After all, pre­vi­ous civil­i­sa­tions from the An­cient Greeks and Egyp­tians, to the great Is­lamic sci­en­tists and as­tronomers of the mid­dle ages, to Europe’s own En­light­en­ment thinkers and even the sci­en­tists of the 19th and early 20th, all had mod­els of the way the uni­verse works, and these mod­els al­lowed them to make pre­dic­tions about things (which is the only way you can re­ally say whether a model is ”good” or not). But they weren’t per­fect. They had holes.

At the ab­so­lute cut­ting edge of par­ti­cle physics and cos­mol­ogy and quan­tum me­chan­ics, all the sci­en­tists work­ing in those fields know it’s a ”work in progress”. Their mod­els can help your car use less fuel, can light up a room on less elec­tric­ity, can treat your can­cer and ac­cu­rately pre­dict if it will rain to­mor­row (next Wed­nes­day, not so much). But they’d don’t pre­dict ev­ery­thing. Yet.

There’s still more to be dis­cov­ered. Lots more. And maybe an equa­tion will pop out of some math­e­mat­ics grad­u­ate’ head, one that will, just like E=MC2 did for nu­clear power, make a trip to Al­pha Cen­tauri just an­other thing that hu­mans do.

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