The sharp image of a galaxy halfway
across the universe might shred modern theories about the structures of time
and space, and change the way astrophysicists view the “Big Bang,” according
to two scientists at The University of Alabama in Huntsville (UAH).
Their findings might also provide important clues to (and cause significant
upheaval among) researchers trying to merge two of the most significant
scientific theories of the last century: Einstein’s theory of general
relativity and Planck’s theory of the quantum.
Using Hubble Space Telescope images of galaxies at least four billion light
years from Earth, UAH’s Dr. Richard Lieu and Dr. Lloyd Hillman tested a
popular theory of modern quantum physics: That time flows in incredibly
small but finite and measurable quantum bits.
Their research findings are scheduled to be published in the March 10
edition of “Astrophysical Journal Letters,” and have been released in the
journal’s website.
Lieu and Hillman used images gathered by the Hubble Space Telescope to look
for patterns that shouldn’t be present if prevailing notions of time quantum
were correct.
“I fully anticipated that the pattern wouldn’t show,” said Lieu, an
associate physics professor at UAH.
Instead, when they looked at Hubble images of galaxies at least four billion
light years from Earth, each image unexpectedly showed a sharp
interferometric pattern — a ring around the galaxy.
Using that data, the UAH team was able to determine that the speed of that
light didn’t fluctuate by more than a few parts in 10^-32 as it traveled
across the cosmos. That measurement is significantly more accurate than
should be possible if quantum theories of time and space are correct.
Their findings will create problems for astrophysicists and cosmologists who
agree with Albert Einstein’s theory that time, gravity and the fabric of
space are different manifestations of the same phenomenon, sort of like
thunder and light are different signatures of lightning. More recently, when
scientists theorized that gravity is composed of quantum energy “packets”
called gravitons, it made sense that time and space would also be composed
of related quantum bits.
Which brings us to Planck time and Planck length, thought to be the shortest
possible measurements of time and distance. Both are based on calculations
of the most energetic radiation theoretically possible. There are twenty
million trillion, trillion, trillion Planck time intervals (5×10^-44) in one
second. Planck length is the distance a beam of light would travel in that
time — about 0.000000000000000000000000000000001 (10^-33) cm.
Tying together the theory of gravitons with the shortest possible
measurements of time, quantum theory says time would move in miniscule,
Planck time-sized bits — like grains of sand passing chaotically through an
hourglass, or a sequence of jittery freeze frames that on average last one
Planck time rather than a continuous, seamless flow.
Scientists say time and distances smaller than Planck scales are “fuzzy,”
since they can’t be measured. If there is a finite limit to the smallest
units of time and distance, however, that means there are limits on how
accurately scientists can measure things like the speed of light.
This limitation opens the possibility of Planck-scale fluctuations in the
speed of light, said Lieu. Because these fluctuations would be extremely
small, however, they would only be evident in light that travels a great
distance. The extended travel gives the slightest variations in speed an
opportunity to spread out and become noticeable.
(The same principle applies to racing events. A sprinter, for instance, one
percent faster than his opponents might win a 100-meter race in a photo
finish, while a marathon runner one percent faster than the field would
finish a race hundreds of meters ahead.)
After billions of years, the faster components of a light wave would be far
enough ahead and the slower components far enough behind that the light’s
wave front would be sufficiently distorted (or blurred) to be seen and
measured by a telescope.
It was that distortion that Lieu and Hillman expected to find in the Hubble
images. Not finding that distortion means time isn’t a quantum function,
says Lieu, and that time might flow fluidly and precisely at intervals
infinitely smaller than Planck time.
“If time doesn’t become ‘fuzzy’ beneath a Planck interval, this discovery
will present problems to several astrophysical and cosmological models,
including the Big Bang model of the universe,” said Lieu. “The Big Bang
theory supposes that at the instant of creation, the quantum singularity
that became the universe would need to have infinite density and
temperature. To avoid that sticky problem, theorists invoked the Planck
time. They said if the instant of creation was also a quantum event, when
space and time were both blurry, then you don’t need infinite density and
temperature at the start of the Big Bang.
“If time moves along like business as usual even at Planck scales, however,
you have to reconcile the Big Bang model with an event that isn’t just off
the scale, it’s infinite!”