Kepler Will Be Used to Measure the Size of the Universe

Article written: 14 Apr , 2009
Updated: 24 Dec , 2015
by

[/caption]

On April 7th, commands were sent to NASA’s exoplanet-hunting Kepler telescope to eject the 1.3×1.7 metre lens cap so the unprecedented mission could begin its hunt for Earth-like alien worlds orbiting distant stars. However, one UK astronomer won’t be using the Kepler data to detect the faint transits of rocky exoplanets in front of their host stars. He’ll be using it to monitor the light from a special class of variable star, and through the extreme precision of Kepler’s optics he will be joining an international team of collaborators to redefine the size of the Universe…

Kepler is carrying the largest camera ever launched into space. The camera has 42 charge-coupled devices (CCDs) to monitor the very slight changes in star brightness as an exoplanet passes in front of its host star. Considering the fact that it is hoped Kepler will detect exoplanets a little larger than our planet (known as super-Earths), the instrument is extremely sensitive. It is for this reason that not only exoplanet hunters are interested in using Kepler’s sensitive eye.

Using Kepler data, Dr Alan Penny, a researcher at the University of St Andrews will be joining a 200-strong team of astronomers to analyse the light not emitted from exoplanet-harbouring stars, but from a smaller group of variable stars that fluctuate in brightness with striking regularity and precision. These stars are Cepheid variables, also known as “standard candles” as they can be relied upon for their strong correlation between period of variability and absolute luminosity. This means that no matter where Cepheids are observed in galaxies or clusters, astronomers can always deduce the distance from the Earth to the Cepheid with great precision. The only thing limiting astronomers is the precision that can be attained by instrumentation, so when Kepler left Earth, carrying the most advanced and sensitive camera ever to be taken into space, Penny and his collaborators jumped at the chance to use Kepler to refine the measurement of the Universe.

While Kepler is doing its exciting planet-hunting, we will be using its extreme precision to resolve a possible problem with our measurement of the size of the Universe,” said Penny. “These variable stars known as ‘Cepheids’ form the base of a series of steps by which we measure the distance to distant galaxies and, through them, we can measure the size of the Universe.”

Current estimates place the size of the Universe at 93 billion light years across, but Penny believes Kepler observations of a small selection of Cepheids may change this value by a few percent. When precision observations of a very precise stellar period-brightness relationship, it’s nice to be able to use the most precise instrument you can lay your hands on. However, our understanding of the “standard candles” themselves is very poor, and small-scale, dynamic changes on the star itself can go unnoticed on the ground. Kepler should shed some light on gaps in our knowledge of Cepheids as well as give us the best-yet measurement of the scale of our Universe.

These Cepheid stars which get brighter and fainter by some tens of percent every ten to a hundred days are mostly understood. But recently it has become clear that our theories of what happens in the outer layers of these stars which cause the variations in brightness do not totally agree with what we see. The exquisite accuracy of Kepler in measuring star brightness, one hundred times better than we can do from the ground, means we can get such good measurements that we should be able to match theory with observation. Resolving the issue may only change estimates of the size of the Universe by a small amount, but we won’t rest easy until the problem is solved.” — Dr Alan Penny

Source: Physorg.com


27 Responses

  1. jeri says

    If the universe has an end what is on the other side?

  2. SimonD says

    Jeri said

    “If the universe has an end what is on the other side?”

    a better question is “does the universe have an end?” because it can be answered with a ‘yes’ or ‘no’. A response ‘no’ means that your question is meaningless.

    Its like asking ‘what is the meaning of life?’ – The question implies that a more fundemental question – ‘does life have a meaning’ (which can be answered answerable ‘yes’ or ‘no’) has already been answered with ‘yes’ otherwise the question, once again, is meaningless.

    Rigour is very important when asking scientific questions. Its an art as much as a science!

  3. SimonD says

    …that said – I wasn’t too rigorous with my typo checking 😉

  4. Olaf says

    I know there is a restaurant at the end of the universe. LOL

    But is cool to have many other different technologie to check if current models are right.

  5. Member
    wantstoknow says

    If the age of the universe is 13.7 billion and the size
    is about 93billion light years..
    did the universe expand faster then the speed of light? or did it have a finite size at the time of the
    big bang?

  6. jeri says

    Maybe we think too small. Always searching for a beginning and an end, not capable of thinking outside the box some might say.
    It may not be a very scientific question but it most certainly has meaning. Perhaps the universe has no end nor beginning. Maybe it has always been and always will be. Most likely the universe is infinite but we can only see a finite section of it due to the finite speed of light and our finite human capabilities. Maybe we created the Big Bang theory to fit within that finiteness of being simply human.

  7. Astrofiend says

    jeri Says:
    April 14th, 2009 at 1:13 pm

    “# jeri Says:
    April 14th, 2009 at 5:11 am

    “If the universe has an end what is on the other side?”

    In my view, an infinite universe (spatial or temporal) is AT LEAST as confounding and impossible to contemplate as a finite universe. That’s not to say that me not being able to contemplate such a thing means that it could not be the case, but I believe the question of ‘what is on the other side of a finite universe’ is no more of a mind bender than ‘the universe goes on literally for ever’.

    That said, there are plenty of explanations for how we could have a finite universe yet no ‘other side’ that is accessible to us, even in theory.

    The usual oversimplified-yet-illustrative picture is the ‘surface of a ball’ example. The surface of a ball is finite in size, and yet if you were a two-dimensional creature confined to its surface, you could travel infinitely far in any direction and not leave the ‘2D-space’ that you are in. Mathematicians would say that the 2D ball’s surface is embedded in a 3D space – the extra dimension being inaccessible to the creature due to the ‘laws’ imposed on its universe. A similar argument is easily extended to space itself. We live in a 4D-spacetime. This could easily have a finite size, but be topologically embedded in a higher space such that one could never leave the space. It has been the subject of serious research, with researchers looking in deep-field photos looking for potentially repeating patterns in the large scale structure of the universe (none has been found though).

    In any event, the question becomes moot because the outside is, by definition, inaccessible to us.

    There are other theories that abound – space could merely be embedded in a higher dimensional ‘brane’, and so this could be what lies outside our immediately observable universe – others have called it hyperspace in former times.

    Actually, the list goes on and I’m tired of typing, but I think it is important to address one thing you have said, and that is “Most likely the universe is infinite but we can only see a finite section of it due to the finite speed of light and our finite human capabilities.” and “Maybe we created the Big Bang theory to fit within that finiteness of being simply human.”

    First of all, you can’t say ‘most likely the universe is infinite’ – there is no evidence for that at all. At best, it is an unresolved question. However, it is highly likely that the part of the universe we see is only a small part of what’s out there due to the finite speed of light.

    Secondly, Big Bang Theory was created by us but not to fit with some preconceived notion of a finite universe – a finite universe was implied by BBT. It was not created to ‘fit with the finiteness of being human’ – it was a theory created to fit with a number of monumental observations that seemed inexplicable in other theoretical frameworks, and crucially, it was consistent with all known laws of physics. It has had it’s successes and failures, and a number of excellent modifications have been proposed that extend the theory admirably, such as inflation and the brane model. These will be falling testable very soon with the launch of the Plank satellite – the predictions from many of BB’s potential successors have been made, and now we await the data…

  8. Astrofiend says

    Now – more on topic – EXCELLENT!

    The discovery of Cepheids was just pure awesomeness, but as a distance marker, they’ve always been plagued by that little bit of uncertainty. Kepler and the upcoming Gaia mission by ESA should put things on a far more steady footing.

    I think refining our distance scale is among the most seemingly inane yet absolutely important work that astronomers can do at the moment. We should aim to get the Cepheid and Type 1a distances calibrated to nothing short of perfection! (I know – I aim high).

  9. Layman says

    Astrofiend? I remember wondering as a ten old so year old boy- what is outside of the universe- my science teacher said that there was nothing- Cannot be true I exclaimed, there is always something on the other side- I guess that we will never know.
    You are so good at explaining things-“Wantaknow” above asked if the Universe is 13.7 billion years old- How can it be 93 billion light years wide. Well that is not exactly what he asked but I am.
    So I looked up- “age of the universe” in wikipedia- it agrees with the size but I came away with just as many questions- I know that it is thought that Inflation (expansion faster than the speed of light) happened in the earliest moments after the big bang, but it does not account for age difference. I will never understand the math- but perhaps a plain English explanation-if there is one would help some of us-like me!

  10. Chuck Lam says

    Hmmm . . .universe 93 billions light years across . . . 13.7 billion years old . . . Hubble Bubble 27.4 billion light years diameter. Occum’s razor suggests anything with an edge must have ‘something’ on either side. The same can be stated for ‘time.’ There simply must have been ‘some time’ before an event and most likely there will be time after the same event. A guess is space and time are infinite regardless of scientific argument.

  11. Feenixx says

    wantstoknow wonders

    “If the age of the universe is 13.7 billion and the size
    is about 93 billion light years..
    did the universe expand faster then the speed of light?”

    According to the understanding of mainstream science, it DID expand faster than the speed of light, but only for a brief moment: 10e-23 seconds….

    The discrepancy arises from the fact that space itself has expanded since (seen relative to the age of the Universe) the earliest events we can observe have happened.

    BTW, 93 billion light years is the size of the _observable_ Universe – the Whole Thing may be a lot larger.

    I find all of this quite mind boggling, but it seems to work out nicely as a model for doing all kinds of calculations and simulations.

  12. Balaji says

    i think it is the visible universe…

  13. Ignoramus says

    Astrofiend says abot BB theory:
    “it was a theory created to fit with a number of monumental observations that seemed inexplicable in other theoretical frameworks, and crucially, it was consistent with all known laws of physics”
    How is creating something out of nothing “consistent with all known laws of physics” ?
    The Cepheid work is indeed awesome!

  14. Spoodle58 says

    I love this stuff, when people come up with other uses for mission data.

    What else can we do with what missions are running or going to run?

  15. Layman says

    Feelix- Thanks I think! And thank you for trying to explain.

    “The discrepancy arises from the fact that space itself has expanded since (seen relative to the age of the Universe) the earliest events we can observe have happened.”

    Does this mean that space has expanded faster than the speed of light?
    Sorry I may never understand this concept!

  16. jerry says

    The first problem one runs across in trying to explain the universe, is that it exists.

  17. Layman says

    Jerry- The Universe does exist -take my word for it!

    There was an article in Discover magazine this month where one scientist suggested that the universe might not exist if we were not here to observe it.

    I hope that he is wrong-But the idea of what we would have to do to prove his theory does not appeal to me.

  18. pantzov says

    i’m proud of you guys for not accepting the conventional size and age theories of the universe.
    (i think that) we most likely will never know the true size of the universe and current theories of it’s age seem doubtful as well.
    one of the things i like about UT is this freedom and variance of opinions.
    some of my companions are so stuck in modern theory that they almost seem like cult members at times.

  19. pantzov says

    p.s. i think we will be seeing MANY more KEPLER-related stories on UT in the future.
    people have been looking forward to this guy for years.

  20. Travis says

    what if there where more than one big bangs farther out what then, would we call this “chunk” our galaxy and in this case our big bang. what would we call it. I always picture it as a small fish looking at open ocean.

  21. Travis Smith says

    what if there where more than one big bangs farther out what then, would we call this “chunk” our galaxy and in this case our big bang. what would we call it. I always picture it as a small fish looking at open ocean.

  22. Feenixx says

    Layman wonders:

    “The discrepancy arises from the fact that space itself has expanded since (seen relative to the age of the Universe) the earliest events we can observe have happened.”

    Does this mean that space has expanded faster than the speed of light?”

    It doesn’t, but I can’t explain it without writing a rather long paper. Also: 93 billion light years is the estimated MINIMUM size. The observable Universe could well be larger – one calculation I did for myself resulted in over 101 billion light years which could possibly be observed, but I could be wrong. Cosmology and physics are only a hobby for me. I lack the in-depth knowledge to be able to claim that this is correct.

    Travis Smith asks:
    “what if there where more than one big bangs farther out what then, would we call this “chunk” our galaxy and in this case our big bang. what would we call it.”

    people with minds capable of comprehending all of this propose to call it “Multiverse”. There are actually different ways of describing a Multiverse: M Theory and similar ones, and also the Many Worlds Interpretation of Quantum Mechanics, which is different again and even more mind boggling. Putting all of it together, there could even be “nested Multiverses”.
    I’m in no way qualified to propose any such hypothesis, but I find thinking about such issues stimulating and entertaining.

  23. Sili says

    Awesome!

    Glad to hear the thing can be used for something interesting!

    (Sorry, I just find cosmology more fascinating than the question of planets and life.)

  24. Sili says

    Awesome!

    Good to hear the thing can be used for something interesting!

    (Sorry, I just find cosmology more fascinating than the more ‘parochial’ question of how and where planets and life form.)

  25. Sili says

    Gah! Sorry. Got an errormessage.

Leave a Reply