Physics fun­da­men­tal to ev­ery­thing

The Expositor (Brantford) - - NEWS - TIM PHILP Tim Philp has en­joyed sci­ence since he was old enough to read. Hav­ing worked in tech­ni­cal fields all his life, he shares his love of sci­ence with read­ers weekly. He can be reached by e-mail at: tphilp@bfree.on.ca or via snail mail c/o The Ex­posi

Physics is our most fun­da­men­tal sci­ence.

It is an at­tempt to un­der­stand, well, ev­ery­thing. What is mat­ter made of? What is en­ergy? How are they re­lated? Why do things be­have as they do? All th­ese ques­tions and more are fun­da­men­tal to un­der­stand­ing the world.

Physics in­cor­po­rates the ba­sis for chem­istry, bi­ol­ogy, ge­ol­ogy and astron­omy, and is at the heart of all en­gi­neer­ing dis­ci­plines. About the only sci­ence that does not have physics at its heart is math­e­mat­ics, yet math­e­mat­ics is the lan­guage of physics. With­out an un­der­stand­ing of math­e­mat­ics, you can never truly un­der­stand physics and, with­out physics, you can never truly un­der­stand any­thing.

Physics seems to come in cy­cles and each cy­cle comes with sig­nif­i­cant over­turn­ing of what we thought we knew.

Back in 1896, when Wil­frid Lau­rier was prime min­is­ter of Canada, an em­i­nent physi­cist said that the fu­ture of physics is to be found in the sixth dec­i­mal place. What he was say­ing was that we un­der­stand how ev­ery­thing works and are tak­ing more pre­cise mea­sure­ments rather than dis­cov­er­ing any­thing new.

That state­ment was made just a few years be­fore the dis­cov­ery of quan­tum physics that rev­o­lu­tion­ized our un­der­stand­ing of time and space. They no longer were con­stants and could change un­der ex­treme con­di­tions. In­deed, time and space were in­ex­tri­ca­bly linked and mov­ing through one changed the other.

We have, more re­cently, had an­other rev­o­lu­tion in our un­der­stand­ing of the phys­i­cal world. We can trace the evo­lu­tion of the uni­verse to within bil­lionths of a sec­ond af­ter the Big Bang, the event that cre­ated the uni­verse and we have learned that the uni­verse is not what we thought. Only 4.8 per cent of the uni­verse can be ac­counted for by or­di­nary mat­ter. And 26.8 per cent of the uni­verse is com­posed of some­thing called dark mat­ter and an astounding 68.3 per cent of the uni­verse is com­posed of some­thing we call dark en­ergy. In other words, all the stars, gal­ax­ies and ev­ery­thing else that we can see make up less than five per cent of the uni­verse. The rest is some­thing that we do not un­der­stand.

Dark mat­ter was dis­cov­ered when as­tronomers started cal­cu­lat­ing the or­bits of stars and gas in nearby gal­ax­ies and found that the stars were mov­ing too fast to be held in the galaxy by grav­ity alone. It was pos­tu­lated that an un­de­tectable form of mat­ter that is only known by its grav­i­ta­tional ef­fects must be hold­ing th­ese stars in the galaxy at their present speeds.

We have lots of ideas what this sub­stance could be, but noth­ing de­fin­i­tive. One of the great quests of physics is to come up with a “the­ory of ev­ery­thing” that will ex­plain all phe­nom­ena. Any the­ory of ev­ery­thing must ex­plain the ex­is­tence and na­ture of dark mat­ter.

Dark en­ergy is some­thing else com­pletely. One of the con­se­quences of the Big Bang is that the uni­verse is ex­pand­ing and has been for al­most 15 bil­lion years. It is space it­self that is ex­pand­ing, not sim­ply a bunch of gal­ax­ies mov­ing away from an ex­plo­sion. Our pre­vi­ous un­der­stand­ing of physics would tell us that the gal­ax­ies would con­tinue to ex­pand, be­ing slowed by their mu­tual grav­i­ta­tional at­trac­tion.

What we have ob­served is that, un­til about five bil­lion years ago, the uni­verse’s ex­pan­sion was in­deed slow­ing as you would ex­pect. How­ever, some­thing hap­pened then that de­fies ex­pla­na­tion. The ex­pan­sion of the uni­verse started to speed up. It was as if you tossed a ball in the air and saw it rise and slow its speed and then sud­denly start to ac­cel­er­ate up­wards at an ever-in­creas­ing rate.

We know of no mech­a­nism that would cause this and have pos­tu­lated some­thing called dark en­ergy to ex­plain this ef­fect. As usual, we have lots of the­o­ries to ex­plain this ex­pan­sion, but no data that help us choose between them.

It seems that ev­ery time we think we have a com­plete un­der­stand­ing of the uni­verse, the uni­verse re­veals some­thing un­ex­pected and rev­o­lu­tion­ary. A few years ago, I had a jour­nal­ist’s tour of the Large Hadron Col­lider in Geneva. I had lunch with sev­eral physi­cists, who, at the time, were ex­pect­ing to an­nounce the dis­cov­ery of the Higgs Bo­son, the par­ti­cle that is re­spon­si­ble for grav­ity.

Ev­ery­one ex­pected they would find it. I asked what if they don’t?

A physi­cist got a gleam in his eye and said that would make things “very in­ter­est­ing in­deed. It would mean we don’t un­der­stand ev­ery­thing yet.”

There is sup­pos­edly an old Chi­nese curse that goes: “May you live in in­ter­est­ing times.” When it comes to physics, that might be a bless­ing rather than a curse.

IN­TER­NET ILLUSTRATION

With­out an un­der­stand­ing of math­e­mat­ics, you can never truly un­der­stand physics and, with­out physics, you can never truly un­der­stand any­thing, writes columnist Tim Philp.

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