Error on Yahoo story today on age and size of universe?

Question

According to a story featured on Yahoo today, "Scientists now estimate the universe to be about 13.7 billion years old (a figure that has seemed firm since 2003, based on measurements of radiation leftover from the Big Bang) and about 156 billion light-years wide. The new finding implies that the universe is instead about 15.8 billion years old and about 180 billion light-years wide."

Surely the decimal point in this story is in the wrong place. How could the universe be more than 10 times as wide (in light years) as the age of the universe? Either they have the decimal point in the wrong place or the stars are travelling away from each other through space several times faster than the speed of light.

Yes, I understand that space is expanding. But can it be expanding at more than 10 times the speed of light?

Yes, I did take into consideration that space expands in more than one direction. Since the article said "wide" I assumed that we are talking about a maximum speed of twice the age of the universe. That is why I said, "several times" and not "more than ten times."

Bruce's answer did indeed raise more questions than it answered. Actually I had already looked that article up in Wikepedia before I asked the question. Bruce and some others have given me something to think about. I am still studying the answers.

Answer 1

there was a period of time shortly after the big bang called the "inflationary period." your suspicion is correct -- no object inside the universe can move faster than light, so if that was all that was going on, you couldn't have something that size in that amount of time. but there is nothing to prevent space itself from expanding faster than the speed of light, which is what is theorized to have happened during the inflationary period. this is the only current theory with wide acceptance that explains why space looks so uniform in all directions.

Answer 2

This is a dfficult subject, Read the following item from Wikipedia and see if you can make sense of it. I can't.

"The observable universe is a term used in physical cosmology to describe the maximum possible spatial extent of the Universe, as calculated from the space-time radius of curvature, and other astrophysical standards such as quasar distributions.

Both popular and professional research articles in cosmology often use the term "universe" when they really mean "observable universe". The reason for this is that unobservable physical phenomena are scientifically irrelevant; that is, they cannot affect any events that we can perceive, and therefore causally do not exist. They also cannot be measured, and therefore hypotheses about parts of the universe that are not observable may be ignored.

Size
In the sense of a comoving distance scaled to the current conditions, the universe is 13.7 billion light years in radius because the universe is 13.7 billion years old. However, space itself may expand faster than the speed of light making the physical size associated with this much larger. This occurs when space expands while a photon is in transit, hence the photon must traverse a proper distance which is greater than the Hubble distance, or the traditionally defined edge of the observable universe.

There is some disagreement as to exactly how large the observable universe in proper distance is: a study of the cosmic microwave background radiation by WMAP in May 2004 states the universe is at least 78 billion light years in radius, yet the March 2005 issue of Scientific American cites a figure of 46 billion light years in every direction. The ambiguity in size is dependent on the detailed models of Hubble's law, especially the nonlinear nature of dark energy component of the universe which is causing the expansion of the universe to accelerate.

In practice, we can only observe objects as far as the surface of last scattering 300,000 years after the big bang when the universe had cooled sufficiently to permit electrons to bind to atomic nuclei, which brought a halt to the Compton scattering of ambient photons, meaning that the photons can survive long enough to reach Earth. However, it may be possible to infer information from before this time through the detection of gravitational waves."

I think I have raised more questions than I have resolved, here!

Answer 3

The light reaching us from the edge of the universe took 13.6 billion years to get here, but in 13.6 billion years the entire universe would have expanded to be 156 billion light years across (so it has a radius of half that number). Space isn't expanding at several times the speed of light. Check out this article: The guy explains your answer somewhere in there:
http://www.msnbc.msn.com/id/5051818/

Answer 4

I think your problem is that you're thinking that space only expands in one direction. If the Universe did expand in one direction, then the two figures would be the same. But the Universe is spreading in all directions. This makes the Universe"s dimensions exponentially larger than its age.

Answer 5

I don't know if the Yahoo article is in error or not, but what it states is perfectly consistent with current scientific knowledge.

Spatial distance between two points can increase faster than light speed.


Consider this:

If two photons (light particles) are released in space in directly opposite directions at the same instant, what is the spatial distance between those photons after one second, according to an observer located at their point of origin?

Both photons are travelling at light speed (299,792.458 km/s = 186,282.497 mi/s) in directly opposite directions, which does not violate any known physical laws, but the distance or space between them is still increasing at double the speed of light.

Now, if you consider the large-scale expansion of space-time integrated over billions of years in conjunction with this concept, the universe can indeed, as a whole, expand at considerably faster than light speed without violating anything we currently understand about physics. Thus, the universe can seem to be much wider than it should be at first glance when one considers the speed of light without both expansion concepts taken into account.

No physical masses are exceeding light speed, in full accordance with relativity, but nevertheless, the distance between points with or without mass can still increase faster than light speed.

See the nature of the apparent paradox?

The photons created shortly after the theoretical 'big bang' can therefore be much farther from its epicentre than can be accounted for by the speed of light alone, making the universe seem much too big with respect to the time passed since that moment.

The 'speed' of space itself is independent of the relativistic limit of light speed, which only applies to things with an electromagnetic component. Can you name a single particle ever discovered that is NOT composed of or directly connected to electromagnetic energy and its motive limitations?

What we call space has no 'substance' under the dominion of the electromagnetic laws of motion and is therefore independent of those motive laws. Consequently, even though nothing can supposedly travel faster than light speed, the space between two points can still increase faster than light speed for the combined reasons stated above.

This in no way violates a single known fact of physics but instead, provides new insights into the mysterious way the natural universe works that escaped our attention before.

This is one reason why the findings were such a surprise to many of those scientists of the old school of thought. Now they will be forced to reevaluate and modify several previous theories to accommodate the new observations.

In fact, I'm not sure how many physics students are aware of it yet, but the 'edge' of the observable universe is accelerating as it expands over time, rather than slowing down as older theories postulated.

Hubble's law of universal expansion is going to need some serious revision because of this discovery, assuming the observations are correct.

Answer 6

not only are stars moving away from each other SPACE it's self is expanding

Answer 7

Trying to comprehend quantum physics makes my brain bleed. I'm sure it makes sense to the eggheads.