One of the most powerful known magnifying lenses isn’t found on Earth. The lens is built from stars, gas and dark matter and lies about 4 billion light-years away. As astronomers peer through it, they are finding the seeds of galaxies that were scattered around the universe more than 13 billion years ago.
The lens is known as Abell 2744, a cosmic pileup where four groups of galaxies are colliding to create one gargantuan gathering with the mass of about 2 quadrillion suns (SN: 6/13/15, p. 32). The gravity from all that mass redirects any light that tries to sneak past, bending and focusing it, creating bigger and brighter images of galaxies far beyond the cluster.
Abell 2744 is useful as an astronomical tool because the universe obeys Albert Einstein’s general theory of relativity. That theory describes how gravity, mass, space and time work together to build a universe. It forms the bedrock of science’s understanding of the cosmos. And for astronomers today, two primary consequences of general relativity — mass’s power to focus light plus the ripples in spacetime generated when masses accelerate — provide robust tools for investigating the cosmos. Giant lenses in space are at the forefront of efforts to explore the origins of galaxies. Elusive gravitational waves, meanwhile, can reveal unseen collisions between stellar corpses, such as black holes and neutron stars.
Gravitational lenses and waves are not new ideas. Einstein knew that his theory implied that both exist. In 1937, Caltech astrophysicist Fritz Zwicky proposed that lenses should be found around some massive galaxies. Decades passed before astronomical technology verified that idea: It wasn’t until 1979 that astronomers detected a real-life example of a gravitational lens in the double image of a quasar — side-by-side glimpses of a galaxy’s blazing heart, resembling a pair of oncoming headlights.
Einstein calculated how the gravity of one star could amplify the light of another more distant star, but he also reasoned that the odds of seeing it are abysmally low. In recent years, the Optical Gravitational Lensing Experiment, one of several efforts to detect celestial bodies wandering in front of stars in the galaxy, has recorded about 2,000 possible events annually.
“It’s amusing how today lensing is so respected,” says Richard Ellis, an astrophysicist at the European Southern Observatory in Garching, Germany. “I’m old enough to remember when it was regarded as a bit wacky.”
Over the last couple of decades, lensing has been used to study all manner of things. Some nearby lenses forged from single stars have revealed planets in our own galaxy, including a few orphans that drift through the Milky Way without a sun to call home (SN: 4/4/15, p. 22). Other lenses, like Abell 2744, let astronomers peer across the cosmos to see galaxies growing up in the early universe.
Seeds of modern galaxies
Telescopes look back in time; light from the most distant locales travels for nearly the entire 13.8-billion-year history of the universe. As astronomers poke around for galaxies so far away (and so far back in time), they hope to find the seeds of what eventually became modern galaxies. Only abnormally bright galaxies, however, can typically be spotted across such distances.
Everything seen so far at the edge of the universe is the brightest, biggest, craziest at that time,” says Jennifer Lotz, an astrophysicist at the Space Telescope Science Institute in Baltimore. Our galaxy, though, “is not big and crazy; it’s more typical.” To find those more classic, less showy protogalaxies requires a really big magnifying glass.
Lotz is leading a three-year effort, known as the Frontier Fields project, to stare at six massive clusters with the Hubble Space Telescope and hunt for the seeds of galaxies similar to our own. Four clusters have been analyzed; the remaining two are now coming under scrutiny.
While peering through one of the clusters, Abell 2744, astronomers recently found a candidate for one of the most distant galaxies known, a toddler growing up about 500 million years after the Big Bang. The galaxy appears as a faint red smudge — or rather, three smudges — as its light traverses multiple paths through the cluster. This remote galaxy is tiny and dense, squeezing the mass of about 40 million suns into a ball just several hundred light-years across. It’s a pale dot compared with the Milky Way. Images such as these add to astronomers’ scrapbook of how galaxies grew over the history of the universe.
The building blocks of galaxies aren’t the only things lurking behind these lenses. In March, researchers announced that they saw the same supernova explode not once but four times (SN Online: 3/5/15).
“I just did not expect to see that at all,” Lotz says. “We got so lucky. The timing was perfect.”
The light from the exploding star, which took 9.4 billion years to reach Earth, fell squarely on one galaxy sitting in one of the Frontier Fields clusters. That galaxy’s gravity steered the light along four different paths, creating a quadruple replay, with each additional flash appearing days to weeks after its predecessor.
“The story’s not done,” she says. “We expect yet another one to show up in the next year or two.” By studying how the lens warps the light from background galaxies, researchers have calculated that there’s a fifth road for the light to travel along. Astronomers now have a rare opportunity to know about a supernova before it appears. “It’s an amazing example of gravitational lensing,” Lotz says.
Expansion ramped up
Strong gravitational lenses built by massive clusters are powerful tools. But they’re not that common. The light from most galaxies doesn’t pass near a cluster such as Abell 2744 on its way to Earth. But there are plenty of smaller clusters and long rivers of galaxies, known as galaxy filaments, that fiddle with the light and create weak lenses. “Every distant object has its image distorted by a small amount,” says Joshua Frieman, an astrophysicist at the Fermi National Accelerator Laboratory in Batavia, Ill.

That subtle distortion could be a key to unraveling one of the thorniest mysteries in modern astronomy: what’s causing the expansion of the universe to speed up?
Supernovas in other galaxies appear farther away than would be expected from a gradually expanding universe. Around 7 billion years ago, something stepped on the cosmic accelerator and picked up the pace of the expansion.
Researchers call this repulsive force “dark energy” (SN: 5/5/12, p. 17). They don’t know exactly what it is, but one idea is that it is some intrinsic property of space that has always been there, lurking in the background. At some point, as the universe stretched out, the density of matter and energy dropped enough for dark energy to become dominant.
The idea started with Einstein when he realized that his theory described an unstable universe, one in which gravity could pull all its stars inward in a massive collapse. That clearly hadn’t happened, so he fudged his equations and added in a “cosmological constant” to set things right.
“In order to arrive at this consistent view,” Einstein wrote in 1917, “we admittedly had to introduce an extension of the field equations of gravitation which is not justified by our actual knowledge of gravitation.”
He dropped the idea after Edwin Hubble reported in 1929 that galaxies appeared to recede from each other at ever greater speeds the farther away they were — a discovery that implied the universe was expanding. But Einstein’s creative accounting has come back into vogue. Today his cosmological constant might be the parameter that describes how dark energy inflates the universe.
Astronomers need to know a few more things about dark energy, though. For example, is dark energy truly constant, Ellis asks, or has it changed over time? “Until we measure it as a function of time,” he says, “we don’t know.”
Dark energy competes with dark matter — an elusive substance that holds together galaxies and their clusters — to erect the scaffolding for the universe, the places where atoms can get together and form stars and planets. Dark matter pulls things together and dark energy tries to pry it all apart. “It’s an epic struggle,” Frieman says.
Frieman leads a project called the Dark Energy Survey, one part of which is spending five years tracking how this tug-of-war has changed over time. The survey is looking for weak gravitational lenses created by that scaffolding. Hidden caches of dark matter slightly skew images of thousands of galaxies that share the same patch of sky. By measuring the very subtle distortions of about 200 million galaxies, researchers are mapping dark matter clumps back to a time when the universe was about half its current size (SN: 5/16/15, p. 9). Knowing how the cosmic clumpiness changed since then will help researchers get a sense of how, or if, dark energy changed as well.
The Dark Energy team is in its third year and is beginning to analyze the data from its first season. Frieman expects that the combined data from the first two years should start to rule out some ideas about what dark energy is.
Ripples in space
Even with gravitational lenses, some things are just too far or too faint to be seen. Einstein’s universe, fortunately, has a work-around: gravitational waves. Gravity is caused when mass puckers the fabric of spacetime. Like a ball bouncing off a rubber sheet, any accelerating mass should send out gravitational waves, ripples that cause space itself to stretch and squeeze.
Story continues after graphic
Creating detectable flutters requires cataclysmic events. Colliding black holes, merging neutron stars and even the Big Bang itself (SN: 2/21/15, p. 13) should send out ripples in space that echo across the cosmos. If there were a way to sense these spacetime swells, astronomers could investigate entities whipping around the universe that might otherwise remain unseen.
Searches for such signals have been under way at the Laser Interferometer Gravitational-Wave Observatory, or LIGO, twin facilities in Louisiana and Washington state. Should a wave wash over the Earth, the precise distance between pairs of mirrors suspended at the ends of perpendicular 4-kilometer-long tubes will oscillate as the space between the mirrors expands and contracts. Lasers that ricochet within these tubes can sense changes in distance far less than a thousandth of the width of a proton.
This article appears in the October 17, 2015, Science News with the headline, “Magnifying the cosmos: Using general relativity to see deep into space.”
Source: Using general relativity to magnify the cosmos | Science News
Hey! Would you mind if I share your blog with
my myspace group? There’s a lot of folks that I think
would really enjoy your content. Please let me
know. Many thanks
LikeLike
Hey there! This post couldn’t be written any better! Reading through this post reminds me of
my good old room mate! He always kept chatting about this.
I will forward this article to him. Pretty sure he will have a good read.
Many thanks for sharing!
LikeLike
whoah this blog is great i love reading your posts.
Stay up the great work! You realize, a lot of individuals are looking round for this info, you could help them greatly.
LikeLike
Everyone loves what you guys tend to be up too. Such clever work and coverage!
Keep up the awesome works guys I’ve included you
guys to my own blogroll.
LikeLike
My brother recommended I might like this website.
He was entirely right. This post truly made my day. You can not imagine just how much time I
had spent for this information! Thanks!
LikeLike
This is really interesting, You’re a very skilled blogger.
I’ve joined your rss feed and look forward to seeking more of your magnificent post.
Also, I have shared your website in my social networks!
LikeLike
It’s always great to know ytou helped someone. Thank you for visiting and also for your lovely comment. I hope I can continue to help your community.
LikeLike
Wow! This could be one particular of the most beneficial blogs We’ve ever arrive across on this subject.
Basically Great. I’m also a specialist in this topic therefore I can understand your hard work.
LikeLiked by 1 person
Thanks for one’s marvelous posting! I genuinely enjoyed reading it, you’re a
great author.I will remember to bookmark your blog and may come back
sometime soon. I want to encourage yourself to continue your great work, have a nice afternoon!
LikeLiked by 1 person
It’s in the menu, top right of the screen.
LikeLike
The “About Me” in the menu top right on the screen.
LikeLike
Hi Bernd. The link you are looking for is in the menu, if you click the box to the right of the QuantumBits logo on the top right of the screen, you will find it in there. Thank you for the visit and the comment.
LikeLike
I’m not that much of a online reader to be honest but
your sites really nice, keep it up! I’ll go ahead and bookmark
youhr site to come back later on. All the best
LikeLiked by 1 person
Hey There. I found our weblog the usage of msn. This is a very smartly written article.
I’ll be sure to bookmark it and return to learn extra of
your useful info. Thanks for the post. I will definitely return.
LikeLiked by 1 person
Oh my goodness! Incredible article dude! Thank you, However I am experiencing troubles with
your RSS. I don’t understand the reason why Icannot subscribe to it.
Is there anyone else getting idemtical RSS problems? Anyone who knows the answer can you kindly respond?
Thanx!!
LikeLiked by 1 person
Whats up are using WordPress for your site platform? I’m new
to the blog world but I’m trying to get started and create my own. Do you require any coding knowledge to make your own blog?
Any help would be greatly appreciated!
LikeLiked by 1 person
No real coding knowledge needed, apart from a little HTML perhaps.
LikeLike
Hi my loved one! I wish to say that this article is awesome, great written and
include approximately all significant infos. I’d like to look more posts like this .
LikeLiked by 1 person
Very good article. I am going through many of these issues as well..
LikeLiked by 1 person
bookmarked!!, I like your site!
LikeLiked by 1 person
Hi are using WordPress for your site platform?
I’m new to the bloig world but I’m trying to get syarted and create my own. Do you need any html
coding expertise to ake your own blog? Any help would be
really appreciated!
LikeLiked by 1 person
Hey I know this is off topic but I was wondering if you knew of any
widgets I could add to my blog that automatically tweet my newest twitter updates.
I’ve been looking for a plug-in like this for quite some
time and was hoping maybe you would have some experience
with something like this. Please let me know if you run into anything.
I truly enjoy reading your blog and I look forward to
your new updates.
LikeLiked by 1 person
Twitter widget, you’ll need to create the widget in your Twitter profile first and copy the number in the URL to make it visible on your site.
LikeLike
I’m really inspired with your writing talents and also with the layout on your
blog. Is that this a paid topic or did you customize it yourself?
Either way stay up the excellent quality writing, it is uncommon to see a nice weblog like this
one these days..
LikeLiked by 1 person
Thanks in support of sharing such a nice thinking, post is fastidious, thats why i have
read it fully
LikeLiked by 1 person
Your method of telling everything in this piece of
writing is genuinely good, all be able to easily be aware of
it, Thanks a lot.
LikeLiked by 1 person
Outstanding story there. What occurred after? Thanks!
LikeLiked by 1 person
I like what you guys are usually up too. This sort of clever work and exposure!
Keep up the superb works guys I’ve included you guys to blogroll.
LikeLiked by 1 person
Pretty! This has been a really wonderful article.
Thank you for providing these details.
LikeLiked by 1 person
My partner and I stumbled over here different web address and thought I may as well
check things out. I like what I see so now i’m following you.
Look forward to finding out about your web page repeatedly.
LikeLiked by 1 person
Can I simply say what a comfort to discover a person that really
knows what they are talking about over the internet.
You certainly know how to bring a problem to light and make
it important. More and more people really need to
look at this and understand this side of the story.
It’s surprising you’re not more popular given that you
certainly possess the gift.
LikeLiked by 1 person
When someone writes an article he/she retains the thought
of a user in his/her mind that how a user can understand it.
So that’s why this article is outstdanding.
Thanks!
LikeLiked by 1 person
I every time emailed this web site post page to all my friends,
because if like to read it then my friends will
too.
LikeLiked by 1 person
Superb post but I was wondering if you could write
a litte more on this subject? I’d be very thankful if
you could elaborate a little bit more. Bless you!
LikeLiked by 1 person
Thanks for your personal marvelous posting! I certainly enjoyed reading it, you can be a great author.
I will remember to bookmark your blog and definitely will come
back from now on. I want to encourage you to continue
your great posts, have a nice day!
LikeLiked by 1 person
You can definitely see your enthusiasm within the work you write.
The world hopes for more passionate writers such as you who
aren’t afraid to say how they believe. At all times go after your heart.
LikeLiked by 1 person
Undeniably imagine that that you stated. Your favourite justification seemed
to be at the net the simplest thing to take note of.
I say to you, I definitely get annoyed at the
same time as other people consider concerns that they plainly don’t know about.
You controlled to hit the nail upon the highest and outlined out the whole thing
without having side-effects , people can take a signal.
Will likely be back to get more. Thanks
LikeLiked by 1 person
Do you have a spam issue on this blog; I also am a
blogger, and I was curious about your situation; many of us have
created some nice practices and we are looking to
swap strategies with other folks, be sure to shoot me an email if interested.
LikeLiked by 1 person
I think this is one of the most important information for me.
And i am glad reading your article. But want to remark on some general things, The web site style is ideal, the articles is really
excellent : D. Good job, cheers
LikeLiked by 1 person
It’s going to be finish of mine day, but before end I
am reading this great post to increase my know-how.
LikeLiked by 1 person
I am sure this article has touched all the internet
visitors, its really really fastidious paragraph on building up new weblog.
LikeLiked by 1 person
You actually make it appear so easy together with your presentation but I to find this
matter to be actually something that I think I might never understand.
It seems too complicated and extremely vast for me. I am having a look forward to your subsequent put up, I’ll try to get the hang of
it!
LikeLiked by 1 person
I do not even know how I ended up here, but I thought this post was good.
I don’t know who you are but certainly you are going to a famous blogger if you are not already ;
) Cheers!
LikeLiked by 1 person
That is really attention-grabbing, You are an overly
skilled blogger. I’ve joined your rss feed and
stay up for in quest of extra of your magnificent post. Additionally, I have shared your website in my social
networks
LikeLiked by 1 person
I’ll right away clutch your rss as I can’t in finding your email subscription hyperlink
or e-newsletter service. Do you have any? Kindly let
me recognise in order that I could subscribe. Thanks.
LikeLiked by 1 person
Thanks for pointing it out, I didn’t realise there was no email link. I have placed one in the menu which you will find in the top right of the page, bottom of the menu. Thanks again.
LikeLike