e and space。 it has been calculated that a baseball thrown at a hundred miles an hour willpick up 0。000000000002 grams of mass on its way to home plate。 so the effects of relativityare real and have been measured。 the problem is that such changes are much too small tomake the tiniest detectable difference to us。 but for other things in the universe鈥攍ight；gravity； the universe itself鈥攖hese are matters of consequence。
so if the ideas of relativity seem weird； it is only because we don鈥檛 experience these sorts ofinteractions in normal life。 however； to turn to bodanis again； we all monly encounterother kinds of relativity鈥攆or instance with regard to sound。 if you are in a park and someoneis playing annoying music； you know that if you move to a more distant spot the music willseem quieter。 that鈥檚 not because the musicis quieter； of course； but simply that your positionrelative to it has changed。 to something too small or sluggish to duplicate this experience鈥攁snail； say鈥攖he idea that a boom box could seem to two observers to produce two differentvolumes of music simultaneously might seem incredible。
the most challenging and nonintuitive of all the concepts in the general theory of relativityis the idea that time is part of space。 our instinct is to regard time as eternal； absolute；immutable鈥攏othing can disturb its steady tick。 in fact； according to einstein； time is variableand ever changing。 it even has shape。 it is bound up鈥斺�渋nextricably interconnected；鈥潯nstephen hawking鈥檚 expression鈥攚ith the three dimensions of space in a curious dimensionknown as spacetime。
spacetime is usually explained by asking you to imagine something flat but pliant鈥攁mattress； say； or a sheet of stretched rubber鈥攐n which is resting a heavy round object； suchas an iron ball。 the weight of the iron ball causes the material on which it is sitting to stretchand sag slightly。 this is roughly analogous to the effect that a massive object such as the sun（the iron ball） has on spacetime （the material）： it stretches and curves and warps it。 now ifyou roll a smaller ball across the sheet； it tries to go in a straight line as required by newton鈥檚laws of motion； but as it nears the massive object and the slope of the sagging fabric； it rollsdownward； ineluctably drawn to the more massive object。 this is gravity鈥攁 product of thebending of spacetime。
every object that has mass creates a little depression in the fabric of the cosmos。 thus theuniverse； as dennis overbye has put it； is 鈥渢he ultimate sagging mattress。鈥潯ravity on this view is no longer so much a thing as an oute鈥斺�渘ot a 鈥榝orce鈥櫋ut a byproduct of thewarping of spacetime；鈥潯n the words of the physicist michio kaku； who goes on： 鈥渋n somesense； gravity does not exist； what moves the planets and stars is the distortion of space andtime。鈥�
of course the sagging mattress analogy can take us only so far because it doesn鈥檛incorporate the effect of time。 but then our brains can take us only so far because it is sonearly impossible to envision a dimension prising three parts space to one part time； allinterwoven like the threads in a plaid fabric。 at all events； i think we can agree that this wasan awfully big thought for a young man staring out the window of a patent office in thecapital of switzerland。
among much else； einstein鈥檚 general theory of relativity suggested that the universe mustbe either expanding or contracting。 but einstein was not a cosmologist； and he accepted theprevailing wisdom that the universe was fixed and eternal。 more or less reflexively； hedropped into his equations something called the cosmological constant； which arbitrarilycounterbalanced the effects of gravity； serving as a kind of mathematical pause button。 bookson the history of science always forgive einstein this lapse； but it was actually a fairlyappalling piece of science and he knew it。 he called it 鈥渢he biggest blunder of my life。鈥�
coincidentally； at about the time that einstein was affixing a cosmological constant to histheory； at the lowell observatory in arizona； an astronomer with the cheerily intergalacticname of vesto slipher （who was in fact from indiana） was taking spectrographic readings ofdistant stars and discovering that they appeared to be moving away from us。 the universewasn鈥檛 static。 the stars slipher looked at showed unmistakable signs of a doppler shift5鈥攖hesame mechanism behind that distinctive stretched…out yee…yummm sound cars make as theyflash past on a racetrack。 the phenomenon also applies to light； and in the case of recedinggalaxies it is known as a red shift （because light moving away from us shifts toward the redend of the spectrum； approaching light shifts to blue）。
slipher was the first to notice this effect with light and to realize its potential importancefor understanding the motions of the cosmos。 unfortunately no one much noticed him。 thelowell observatory； as you will recall； was a bit of an oddity thanks to percival lowell鈥檚obsession with martian canals； which in the 1910s made it； in every sense； an outpost ofastronomical endeavor。 slipher was unaware of einstein鈥檚 theory of relativity； and the worldwas equally unaware of slipher。 so his finding had no impact。
glory instead would pass to a large mass of ego named edwin hubble。 hubble was born in1889； ten years after einstein； in a small missouri town on the edge of the ozarks and grewup there and in wheaton； illinois； a suburb of chicago。 his father was a successful insuranceexecutive； so life was always fortable； and edwin enjoyed a wealth of physicalendowments； too。 he was a strong and gifted athlete； charming； smart； and immensely good…looking鈥斺�渉andsome almost to a fault；鈥潯n the description of william h。 cropper； 鈥渁n5named for johann christian doppler； an austrian physicist； who first noticed the effect in 1842。 briefly； whathappens is that as a moving object approaches a stationary one its sound waves bee bunched up as they cramup against whatever device is receiving them （your ears； say）； just as you would expect of anything that is beingpushed from behind toward an immobile object。 this bunching is perceived by the listener as a kind of pinchedand elevated sound （the yee）。 as the sound source passes； the sound waves spread out and lengthen； causing thepitch to drop abruptly （the yummm）。
adonis鈥潯n the words of another admirer。 according to his own accounts； he also managed tofit into his life more or less constant acts of valor鈥攔escuing drowning swimmers； leadingfrightened men to safety across the battlefields of france； embarrassing world…championboxers with knockdown punches in exhibition bouts。 it all seemed too good to be true。 it was。
for all his gifts； hubble was also an inveterate liar。
this was more than a little odd； for hubble鈥檚 life was filled from an early age with a levelof distinction that was at times almost ludicrously golden。 at a single high school track meetin 1906； he won the pole vault； shot put； discus； hammer throw； standing high jump； andrunning high jump； and was on the winning mile…relay team鈥攖hat is seven first places in onemeet鈥攁nd came in third in the broad jump。 in the same year； he set a state record for the highjump in illinois。
as a scholar he was equally proficient； and had no trouble gaining admission to studyphysics and astronomy at the university of chicago （where； coincidentally； the head of thedepartment was now albert michelson）。 there he was selected to be one of the first rhodesscholars at oxford。 three years of english life evidently turned his head； for he returned towheaton in 1913 wearing an inverness cape； smoking a pipe； and talking with a peculiarlyorotund accent鈥攏ot quite british but not quite not鈥攖hat would remain with him for life。
though he later claimed to have passed most of the second decade of the century practicinglaw in kentucky； in fact he worked as a high school teacher and basketball coach in newalbany； indiana； before belatedly attaining his doctorate and passing briefly through thearmy。 （he arrived in france one month before the armistice and almost certainly never hearda shot fired in anger。）in 1919； now aged thirty； he moved to california and took