Skip to comments.ASTRONOMERS CRUNCH NUMBERS, UNIVERSE GETS BIGGER
Posted on 08/03/2006 12:52:54 PM PDT by PatrickHenry
That intergalactic road trip to Triangulum is going to take a little longer than you had planned.
An Ohio State University astronomer and his colleagues have determined that the Triangulum Galaxy, otherwise known as M33, is actually about 15 percent farther away from our galaxy than previously measured.
This finding implies that the Hubble constant, a number that astronomers rely on to calculate a host of factors -- including the size and age of the universe -- could be significantly off the mark as well.
That means that the universe could be 15 percent bigger and 15 percent older than any previous calculations suggested.
The astronomers came to this conclusion after they invented a new method for calculating intergalactic distances, one that is more precise and much simpler than standard methods. Kris Stanek, associate professor of astronomy at Ohio State, and his coauthors describe the method in a paper to appear in the Astrophysical Journal (astro-ph/0606279).
In 1929, Edwin Hubble formulated the cosmological distance law that determines the Hubble constant. Scientists have disagreed about the exact value of the constant over the years, but the current value has been accepted since the 1950s. Astronomers have discovered other cosmological parameters since then, but the Hubble constant and its associated methods for calculating distance haven't changed.
"The Hubble constant used to be the one parameter that we knew pretty well, and now it's lagging behind. Now we know some things quite a bit better than we know the Hubble constant," Stanek said. "Ten years ago, we didn't even know that dark energy existed. Now we know how much dark energy there is -- better than we know the Hubble constant, which has been around for almost 80 years."
Still, Stanek said he and his colleagues didn't start this work in order to change the value of the Hubble constant. They just wanted to find a simpler way to calculate distances.
To calculate the distance to a faraway galaxy using the Hubble constant, astronomers have to work through several complex steps of related equations, and incorporate distances to closer objects, such as the Large Magellanic Cloud.
"In every step you accumulate errors," Stanek said. "We wanted an independent measure of distance -- a single step that will one day help with measuring dark energy and other things."
The new method took 10 years to develop. They studied M33 in optical and infrared wavelengths, checking and re-checking measurements that are normally taken for granted. They used telescopes of all sizes, from fairly small 1-meter telescopes to the largest in the world -- the 10-meter telescopes at the Keck Observatory in Hawaii .
"Technologically, we had to be on the cutting edge to make this work, but the basic idea is very simple," he said.
They studied two of the brightest stars in M33, which are part of a binary system, meaning that the stars orbit each other. As seen from Earth, one star eclipses the other every five days.
They measured the mass of the stars, which told them how bright those stars would appear if they were nearby. But the stars actually appear dimmer because they are far away. The difference between the intrinsic brightness and the apparent brightness told them how far away the stars were -- in a single calculation.
To their surprise, the distance was 15 percent farther than they expected: about 3 million light-years away, instead of 2.6 million light-years as determined by the Hubble constant.
If this new distance measurement is correct, then the true value of the Hubble constant may be 15 percent smaller -- and the universe may be 15 percent bigger and older -- than previously thought.
"Our margin of error is now 6 percent, which is actually pretty good," Stanek said. Next, they may do the same calculation for another star system in M33, to reduce their error further, or they may look at the nearby Andromeda galaxy. The kind of binary systems they are looking for are relatively rare, he said, and getting all the necessary measurements to repeat the calculation would probably take at least another two years.
[Co-author info and funding sources omitted from original article.]
Our universe (and there may well be many more universes besides our own) isn't infinite, but there also isn't anything "outside" the universe - the universe is defined as space itself, but space itself has been expanding since the Big Bang. There's no "empty space" outside the universe it's expanding into, though.
I realize it all makes your brain hurt...try reading any of the books from Brian Greene or Michio Kaku.
There may be other universes, but by "the universe" astronomers and physicists mean all the matter (and the space it occupies) that we will ever be able to see, know about or communicate with. According to our current understanding of the laws of nature, if other universes exist there is no way for light, or anything else, to travel from them to us, or any part of our universe, or we to them.
It is a consequence of the theory of General Relativity that our Universe is finite, but it does not exclude the possibility of other universes.
Good thing I filled up before I left town!
For what it's worth, the age of the universe during Einstein's time was 1.5 billion years. Now it is ten times that.
I hope they get a lot more data points.
The reason it makes your brain hurt is that it does't make sense. Space is space. Nothingness is space too. Why can't the scientists just use the magic words: "I DON'T KNOW!"?
This makes more sense, explained this way.
Here is what you are missing. According to Greene, mentioned above, the radius of the universe is 25 billion times bigger than the Hubble radius. The Hubble radius is as far as the Hubble telescope can see, which is nearly all the universe that can ever be seen since the rest of it is leaving us faster than the speed of light. That is, we can see a grain of sand and take that for the entire earth--similar relative scale.
By two years, at least.
Any such "other" universes would have to be strictly orthogonal to our own (no interaction allowed). If you can in any way sense or detect another universe then it's not another universe, it's more of this one.
Which means that there can be no provable nor useful science about "other universes". Any observation of another universe is - by definition - not an observation of another universe.
We should probably stop throwing these loose Star-Trek tropes around IMO. "Parallel Universes", "Alternate Universes" etc - they're fine if you're a lazy SciFi writer and want a quick plot line about evil Spock or a leather-clad Intendant Kira (Freepers will know the DS9 episode I mean!) but they're appalling science.
It can be so red shifted as to be very hard to observe.
This could be very bad news for the universe
Why not? Is that what they told you?
Hmmm...this seems to not be news. Bonanos, Stanek, et al.'s estimate is 61 km per second per million parsecs.
has it between 50 and 100.
There's an interesting essay by Isaac Asimov -- "The Proton-Reckoner" -- published in 1966 -- Hubble's constant was thought to lie between 75 and 175. Asimov takes the lower limit of 75 and calculates an observable universe of radius equal to 13 billion light years. A value of 50 would indicate an observable universe equal to 20 billion light years.
Actually, GR sort of does exclude other universes. It works like this: the laws of our universe are 'balanced' (defined) by the conditions of our universe, thus our particular space and time are fundamental to the definitions of the laws, but prior to the big bang there is no space and time, so ours is the only universe of reality related to space and time ... IOW, it is impossible to experiment or produce data to verify the existence of other universes. Now if you mean to say branes instead of 'other universes' you may have a point there.
No, the universe is definitely finite, though the 'radius' of a 15 billion year old universe might be 40+ billion years thus the horizon is beyond our ever getting information from it. For all we know, the whole 'shebang' may be contracting at some where/when out beyond our information horizon, and in a few million or billion years, we'll be 'incorporated' in the 'renormalization' (collapse).
And...when was it that "they" removed your brain?
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.