63 | Alan Guth was one of the first physicists to hypothesize the existence of inflation, which explains
64 | how the universe expanded so uniformly and so quickly in the instant after the Big Bang 13.8 billion
65 | years
66 | ago.Credit...Rick Friedman for The New York Times
67 |
94 | CAMBRIDGE, Mass. — One night late in 1979, an itinerant young physicist named Alan Guth, with a
95 | new
96 | son
97 | and a year’s appointment at Stanford, stayed up late with his notebook and equations, venturing
98 | far
99 | beyond the world
100 | of known physics.
101 |
102 |
103 |
104 | He was trying to understand why there was no trace of some exotic particles that should have
105 | been
106 | created in the Big Bang. Instead he discovered what might have made the universe bang to begin
107 | with.
108 | A
109 | potential hitch in
110 | the presumed course of cosmic evolution could have infused space itself with a special energy
111 | that
112 | exerted a repulsive force, causing the universe to swell faster than the speed of light for a
113 | prodigiously violent
114 | instant.
115 |
116 |
117 |
118 | “SPECTACULAR REALIZATION,” Dr. Guth wrote across the top of the page and drew a double box
119 | around
120 | it.
121 |
122 |
123 |
124 | On Monday, Dr. Guth’s starship came in. Radio astronomers reported that they had seen the
125 | beginning
126 | of
127 | the Big Bang, and that his hypothesis, known undramatically as inflation, looked right.
128 |
129 |
130 | Reaching back across 13.8 billion years to the first sliver of
132 | cosmic
133 | time with telescopes at the South Pole, a team of astronomers led by
134 | John M. Kovac of the Harvard-Smithsonian Center for Astrophysics detected ripples in the fabric
135 | of
136 | space-time — so-called
137 | gravitational
139 | waves — the signature of a universe being wrenched violently apart when it was roughly a
140 | trillionth of a trillionth of a trillionth of a second old. They are the long-sought smoking-gun
141 | evidence of inflation, proof, Dr. Kovac and his colleagues say, that Dr. Guth was correct.
142 |
153 | Inflation has been the workhorse of cosmology for 35 years, though many, including Dr. Guth,
154 | wondered
155 | whether it could ever be proved.
156 |
157 |
158 | If corroborated, Dr. Kovac’s work will stand as a landmark in science comparable to the recent
159 | discovery
160 | of dark energy pushing the universe apart, or of the Big Bang itself. It would open vast realms
161 | of
162 | time
163 | and space
164 | and energy to science and speculation.
165 |
166 |
167 | Confirming inflation would mean that the universe we see, extending 14 billion light-years in
168 | space
169 | with
170 | its hundreds of billions of galaxies, is only an infinitesimal patch in a larger cosmos whose
171 | extent,
172 | architecture
173 | and fate are unknowable. Moreover, beyond our own universe there might be an endless number of
174 | other
175 | universes bubbling into frothy eternity, like a pot of pasta water boiling over.
176 |
177 |
178 |
‘As Big as It Gets’
179 |
180 | In our own universe, it would serve as a window into the forces operating at energies forever
181 | beyond
182 | the
183 | reach of particle accelerators on Earth and yield new insights into gravity itself. Dr. Kovac’s
184 | ripples
185 | would be
186 | the first direct observation of gravitational waves, which, according to Einstein’s theory of
187 | general
188 | relativity, should ruffle space-time.
189 |
190 |
191 | Marc Kamionkowski of Johns Hopkins University, an early-universe expert who was not part of the
192 | team,
193 | said, “This is huge, as big as it gets.”
194 |
195 |
196 |
197 | Dr. Kovac said the chance that the results were a fluke was only one in 10 million.
198 |
199 |
200 |
201 |
232 |
233 |
234 |
235 |
236 |
237 | The Theory of Inflation
238 |
239 |
240 | Astronomers have found evidence to support the theory of inflation, which explains how the universe
241 | expanded so uniformly and so quickly in the instant after the Big Bang 13.8 billion years ago.
242 |
243 |
244 |
245 |
THE UNIVERSE is just under 14 billion years old. From our position in the
246 | Milky Way galaxy, we can observe a sphere that is now about 92 billion light-years across. But
247 | there's a mystery. Wherever we look, the universe has an even temperature.
248 |
249 |
NOT ENOUGH TIME The universe is not old enough for light to have traveled
250 | the vast distance from one side of the universe to the other, and there has not been enough time for
251 | scattered patches of hot and cold to mix into an even temperature.
252 |
253 |
DISTANT COFFEE At a smaller scale, imagine using a telescope to look
254 | a mile in one direction. You see a coffee cup, and from the amount of steam, you can estimate its
255 | temperature and how much it has cooled.
256 |
257 |
COFFEE EVERYWHERE Now turn around and look a mile in the other
258 | direction. You see a similar coffee cup, at exactly the same temperature. Coincidence? Maybe. But if
259 | you see a similar cup in every direction, you might want to look for another explanation.
260 |
261 |
THE UNIVERSE is just under 14 billion years old. From our position in
262 | the Milky Way galaxy, we can observe a sphere that is now about 92 billion light-years across. But
263 | there's a mystery. Wherever we look, the universe has an even temperature.
264 |
265 |
STILL NOT ENOUGH TIME There has not been enough time to carry coffee
266 | cups from place to place before they get cold. But if all the coffee cups were somehow filled from a
267 | single coffee pot, all at the same time, that might explain their even temperature.
268 |
269 |
270 |
FLUCTUATION Astronomers have now detected evidence of these ancient
271 | fluctuations in swirls of polarized light in the cosmic background radiation, which is energy left
272 | over from the early universe. These are gravitational waves predicted by Einstein.
273 |
274 |
275 |
EXPANSION Returning to our coffee, imagine a single, central pot expanding
276 | faster than light and cooling to an even temperature as it expands. That is something like
277 | inflation. And the structure of the universe mirrors the froth and foam of the original pot.
278 |
279 |
280 | By LARRY BUCHANAN and JONATHAN CORUM
281 |
282 |
283 |
284 |
285 |
286 |
287 |
288 |
289 |
290 |
291 | Dr. Kovac said the chance that the results were a fluke was only one in 10 million.
292 |
293 | Dr. Guth, now 67, pronounced himself “bowled over,” saying he had not expected such a definite confirmation in his lifetime.
294 |
295 |
296 | “With nature, you have to be lucky,” he said. “Apparently we have been lucky.”
297 |
298 |
299 | The results are the closely guarded distillation of three years’ worth of observations and analysis. Eschewing email for fear of a leak, Dr. Kovac personally delivered drafts of his work to a select few, meeting with Dr. Guth, who is now a professor at Massachusetts Institute of Technology (as is his son, Larry, who was sleeping that night in 1979), in his office last week.
300 |
301 |
302 | “It was a very special moment, and one we took very seriously as scientists,” said Dr. Kovac, who chose his words as carefully as he tended his radio telescopes.
303 |
304 |
305 | Andrei Linde of Stanford, a prolific theorist who first described the most popular variant of inflation, known as chaotic inflation, in 1983, was about to go on vacation in the Caribbean last week when Chao-Lin Kuo, a Stanford colleague and a member of Dr. Kovac’s team, knocked on his door with a bottle of Champagne to tell him the news.
306 |
307 |
308 |
309 |
311 |
Stanford Professor Andrei Linde celebrates physics breakthroughCredit... CreditVideo
312 | by StanfordUniversity
313 |
314 | Confused, Dr. Linde called out to his wife, asking if she had ordered anything.
315 |
316 |
317 | “And then I told him that in the beginning we thought that this was a delivery but we did not think that we
318 | ordered anything, but I simply forgot that actually I did order it, 30 years ago,” Dr. Linde wrote in an
319 | email.
320 |
321 |
322 | Calling from Bonaire, the Dutch Caribbean island, Dr. Linde said he was still hyperventilating. “Having news
323 | like this is the best way of spoiling a vacation,” he said.
324 |
325 |
326 | By last weekend, as social media was buzzing with rumors that inflation had been seen and news spread,
327 | astrophysicists responded with a mixture of jubilation and caution.
328 |
329 |
330 | Max Tegmark, a cosmologist at M.I.T., wrote in an email, “I think that if this stays true, it will go down
331 | as one of the greatest discoveries in the history of science.”
332 |
333 |
334 | John E. Carlstrom of the University of Chicago, Dr. Kovac’s mentor and head of a competing project called
335 | the South Pole Telescope, pronounced himself deeply impressed. “I think the results are beautiful and very
336 | convincing,” he said.
337 |
338 |
339 | Paul J. Steinhardt of Princeton, author of a competitor to inflation that posits the clash of a pair of
340 | universes as the cause of genesis, said that if true, the Bicep result would eliminate his model, but he
341 | expressed
342 | reservations about inflation.
343 |
344 |
345 | Lawrence M. Krauss of Arizona State and others also emphasized the need for confirmation, noting that the
346 | new results exceeded earlier estimates based on temperature maps of the cosmic background by the European
347 | Space
348 | Agency’s Planck satellite and other assumptions about the universe.
349 |
350 |
351 | “So we will need to wait and see before we jump up and down,” Dr. Krauss said.
352 |
353 |
354 | Corroboration might not be long in coming. The Planck spacecraft will report its own findings this year. At
355 | least a dozen other teams are trying similar measurements from balloons, mountaintops and space.
356 |
357 |
358 |
359 |
360 | Spirals in the Sky
361 |
362 |
Gravity waves are the latest and deepest secret yet pried out of the cosmic microwaves, which were discovered accidentally by Arno Penzias and Robert Wilson at Bell Labs 50 years ago. They won the Nobel Prize.
363 |
364 |
365 | Dr. Kovac has spent his career trying to read the secrets of these waves. He is one of four leaders of Bicep, which has operated a series of increasingly sensitive radio telescopes at the South Pole, where the thin, dry air creates ideal observing conditions. The others are Clement Pryke of the University of Minnesota, Jamie Bock of the California Institute of Technology and Dr. Kuo of Stanford.
366 |
367 |
368 | “The South Pole is the closest you can get to space and still be on the ground,” Dr. Kovac said. He has been there 23 times, he said, wintering over in 1994. “I’ve been hooked ever since,” he said.
369 |
370 |
371 |
372 | The Bicep2 telescope, in the foreground, was used to detect the faint spiraling gravity patterns — the signature of a universe being wrenched violently apart at its birth.Credit...Steffen Richter/Associated Press
373 |
374 |
375 | In 2002, he was part of a team that discovered that the microwave radiation was polarized, meaning the light waves had a slight preference to vibrate in one direction rather than another.
376 |
377 |
378 | This was a step toward the ultimate goal of detecting the gravitational waves from inflation. Such waves, squeezing space in one direction and stretching it in another as they go by, would twist the direction of polarization of the microwaves, theorists said. As a result, maps of the polarization in the sky should have little arrows going in spirals.
379 |
380 |
381 | Detecting those spirals required measuring infinitesimally small differences in the temperature of the microwaves. The group’s telescope, Bicep2, is basically a giant superconducting thermometer.
382 |
383 |
384 | “We had no expectations what we would see,” Dr. Kovac said.
385 |
386 |
387 | The strength of the signal surprised the researchers, and they spent a year burning up time on a Harvard supercomputer, making sure they had things right and worrying that competitors might beat them to the breakthrough.
388 |
389 |
390 |
391 |
392 | A Special Time
393 |
394 |
395 |
396 | The data traced the onset of inflation to a time that physicists like Dr. Guth, staying up late in his Palo Alto house 35 years ago, suspected was a special break point in the evolution of the universe.
397 |
398 | Physicists recognize four forces at work in the world today: gravity, electromagnetism, and strong and weak nuclear forces. But they have long suspected that those are simply different manifestations of a single unified force that ruled the universe in its earliest, hottest moments.
399 |
400 |
401 |
402 | As the universe cooled, according to this theory, there was a fall from grace, like some old folk mythology of gods or brothers falling out with each other. The laws of physics evolved, with one force after another splitting away.
403 |
404 |
405 |
406 | That was where Dr. Guth came in.
407 |
408 |
409 |
410 | Under some circumstances, a glass of water can stay liquid as the temperature falls below 32 degrees, until it is disturbed, at which point it will rapidly freeze, releasing latent heat.
411 |
412 |
413 |
414 | Similarly, the universe could “supercool” and stay in a unified state too long. In that case, space itself would become imbued with a mysterious latent energy.
415 |
416 |
417 |
418 | Inserted into Einstein’s equations, the latent energy would act as a kind of antigravity, and the universe would blow itself up. Since it was space itself supplying the repulsive force, the more space was created, the harder it pushed apart.
419 |
420 |
421 |
422 | What would become our observable universe mushroomed in size at least a trillion trillionfold — from a submicroscopic speck of primordial energy to the size of a grapefruit — in less than a cosmic eye-blink.
423 |
424 |
425 |
426 | Almost as quickly, this pulse would subside, relaxing into ordinary particles and radiation. All of normal cosmic history was still ahead, resulting in today’s observable universe, a patch of sky and stars billions of light-years across. “It’s often said that there is no such thing as a free lunch,” Dr. Guth likes to say, “but the universe might be the ultimate free lunch.”
427 |
428 |
429 |
430 | Make that free lunches. Most of the hundred or so models resulting from Dr. Guth’s original vision suggest that inflation, once started, is eternal. Even as our own universe settled down to a comfortable homey expansion, the rest of the cosmos will continue blowing up, spinning off other bubbles endlessly, a concept known as the multiverse.
431 |
432 |
433 |
434 | So the future of the cosmos is perhaps bright and fecund, but do not bother asking about going any deeper into the past.
435 |
436 |
437 |
438 | We might never know what happened before inflation, at the very beginning, because inflation erases everything that came before it. All the chaos and randomness of the primordial moment are swept away, forever out of our view.
439 |
440 |
441 |
442 |
“If you trace your cosmic roots,” said Abraham Loeb, a Harvard-Smithsonian astronomer who was not part of the team, “you wind up at inflation.”
443 |
444 |
445 |
446 |
447 |
448 | A version of this article appears in print on March 18, 2014, Section A, Page 1 of the New York edition with
449 | the headline: Space Ripples Reveal Big Bang’s Smoking Gun. Order Reprints | Today’s Paper | Subscribe
451 |
62 | 
86 | 
245 | 
371 |