Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Do stars actually exist beyond our solar system?

  1. Jul 26, 2010 #1
    It is a question i have been thinking about for a while.

    When we look into the sky, are we actually looking at other stars or are we looking at our own sun from lots of different angles, we know light bends with the gravitational pull of planets. is it not possible that the light we see from stars is actually just the light from our sun bent around the gravitional bodies in our solar system. surely if not all of them are our sun then atleast some of them must be! Also when we look into space we can see lots of amazing colours of distant solar systems, is it not possible that these are just a result of many paths of light particles interacting with or crossing over each other to cause the effects? All this in mind, how big is our universe, actually!

    I'm not trained in any form of science and there maybe evidence i have not seen so excuse me if the answer is simple.

    many thanks

    Mark John
  2. jcsd
  3. Jul 26, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper

    We also measure different temperatures, chemical constituents and even speeds of different stars - from their light.

    The bending of light by something as tiny (on a universal scale) as a planet is incredibly small. The hipparcos satelite which measured the positions of stars to incredible accuracy just about detected bending form light passing jupiter - but only at the fraction of a billionth of a degree level
  4. Jul 26, 2010 #3
    Hi Mgb

    Thanks for clearing that one up for me.

    One more question though.

    You say that light bends only a small fraction from a planet (tiny on a universal scale) but is there a chance that something larger or a collection of smaller bodies (planets) might bend the light from our sun to the correct degree for us to be able to see if from another angle? has anyone actually discovered the light from our sun that has taken a less direct route to earth?
  5. Jul 26, 2010 #4


    User Avatar

    Staff: Mentor

    Even if it is really possible (not really sure), it would have to be a rediculously strong and properly located black hole to do something like that.
  6. Jul 27, 2010 #5
    A few more questions.

    With everything in mind we have already discussed.

    Has anyone ever viewed the light from any star that has been bent by any gravitational forces?

    Surely in the vastness of space we must be looking at some light that has been significantly bent by gravity?

    Could it be possible that we are seeing some of the stars twice just from different angles?
  7. Jul 27, 2010 #6


    User Avatar
    Science Advisor

    Yes. Indeed, this was one of the first classical tests of GR performed by Arthur Eddington in 1919 where he observed light coming from distant stars bend as they passed behind the sun (this took place during a solar eclipse. see: http://en.wikipedia.org/wiki/Tests_of_general_relativity ).

    Also, the geometry of gravitational lensing is quite distinctive, so it really isn't likely at all that any stars (or galaxies) we see are false images. See http://en.wikipedia.org/wiki/Gravitational_lensing for some example pictures of what lensed objects look like, and know that the night sky doesn't really look like this.
  8. Jul 27, 2010 #7
    I don't see how this idea that sunlight travels through many different trajectories to produce all the different star-images visible from Earth is so easily dismissed. Granted, it would be a major shock to find out all the data that has served as a basis for cosmology is mirage-type effects, but on the other hand it would be interesting to discover how many different effects are possible due to various paths and interactions of divergent light trajectories. The whole idea does seem like a kind of solar-centric cosmosolipsism - but I just don't see how it is 100% excludable.
  9. Jul 27, 2010 #8


    User Avatar
    Gold Member

    We've never seen light act in this manner on any scale we've been able to access. The idea that not only does light act differently on planetary scales, but is so radically different as to make all of hundreds of years of physics completely wrong is far fetched to say the least. You may believe that it is just 1 change that you're proposing, but infact would require probably hundreds of new conjectures to make your 1 change to make sense. For example, how would it account for different temperatures, cataclysmic variables, x-ray binary stars, and a plethora of different things that involves radically different suns and how they interact or the radiation they give off?

    It's like suggesting that the Moon is not actually there but simply a reflection of a soda can i have my driveway. You can immediately name off dozens if not hundreds of things about the Moon that can't be described by said theory
  10. Jul 27, 2010 #9


    User Avatar

    Staff: Mentor

    The answer to all of those is yes.

    Here are four images of the same object, caused by gravitational lensing. Note that the object must be extremely far away and the gravitational field extremely strong to create this (thust the angle of "bend" is very small). http://en.wikipedia.org/wiki/File:Einstein_cross.jpg
  11. Jul 27, 2010 #10
    incorrect. every time you look at a planet in our solar system or the moon you are seeing light from the sun that has reflected off that body. hence, a less direct route was taken.
  12. Jul 27, 2010 #11
    pay close attention to the experiment in 1919 by Eddington. the most important part of it (in regards to this question) is that the images from the distant stars that were measured were different by an INCREDIABLY small margin. for a quanta of light to be bent around as to be seen twice (let alone as many times as there are "object" in the sky) the gravitational pull would require something ridiculusly large as the new star found recently (with 280 solar masses). as has been my experience with such thought, "Its a wonderful idea... but it doesn't work."
  13. Jul 28, 2010 #12
    True, but consider a piece of crumpled aluminum foil reflecting light and all the different configurations and directions it reflects that light. Then consider if the foil was covered with oil and water in such a way that it also had multiple prism effects. My point is that if gravitational lensing would take place as complexly as the crumpling of a wet, oily sheet of aluminum foil, then it is not so far-fetched that the full spectrum of observed stars and galaxies could be artifacts of gravitational optics. Like you, I am not willing to trade in all known astronomy and cosmology for cosmosolipsism but I also don't see any point to burying the very thought of it either. It's simply interesting to take one visible artifact at a time and ask how its image could be the result of gravitational lensing. Could the solar system be like the nucleus of an atom with light trajectories around it as diverse as electron paths around the atomic nucleus? That is an interesting if relatively impractical question, imo. I'm glad this thread was posted and I hope people don't give up this query because it would be a loss of scientific imagination.
  14. Jul 28, 2010 #13
    Besides all the other responses already provided, I believe that the only suitable explanation for stellar parallax is proof that extrasolar stars exist, and that they are not simply multiple images of our own sun. In other words, we can measure the parallax of many of the "close" stars. The Hipparcos satellite has measured over 100,000 stars with detectable parallax. The fact that these stars are perceived to move against the fixed background of more distant stars (i.e. parallax) proves they cannot be images from our own sun. Or put more simply, if the stars were images of our own sun, why would some of them appear to move, while others didn't. That, in and of itself, totally disproves the possibility that the stars are simply multiple images of our own sun.

    As an interesting side-note, besides the aberration of startlight, the first undisputed detection of stellar parallax in 1837, was the first irrefutable evidence that the Earth revolves around the sun.

    And of course, stellar parallax is of "cosmic" importance, as it provides the first rung on the distance scale "ladder", which we use to measure cosmological distances.
  15. Jul 28, 2010 #14


    User Avatar
    Gold Member

    We have read the spectrographs of what? Thousands? Tens- Hundreds-of-thousands of stars?

    None of them have spectral signatures identical to Sol.

    In fact, it might be big news if one of them did!

    This, and a thousand other examples make up an overwhelming preponderance of evidence that stars in the sky are not the sun.
  16. Jul 28, 2010 #15
    What if photon-paths are stratified the way electron shells are, such that some shells "drift" relative to others? Would this not explain the appearance of relative motion between strata of some sets of duplicate images relative to others?
  17. Jul 28, 2010 #16


    User Avatar
    Science Advisor
    Gold Member

    Has anyone mentioned parallax? The distance to many stars has been determined by parallax measurements. The only reasonable explanation is they are vastly distant from earth.
  18. Jul 28, 2010 #17
    Beat you to it. Look three posts up :smile:
  19. Jul 28, 2010 #18
    If I am understanding your question correctly (and I may not be)...then since different stars have different parallaxes, one would have to assign a dedicated shell to each of the thousands of different stars with different parallaxes. Besides, I am not sure how you could reconcile that with the way light behaves...always taking the path of least (minimum) time.
  20. Jul 29, 2010 #19
    However long the conduit of curved spacetime would be to make the sun appear so distant, it would be indistinguishable from a situation in which the path taken by light was actually straight, nor would it appear any different from if it followed a straight path. Light always appears to have followed a straight path because the mind is programmed to perceive images as corresponding with the location of their source. This is why people who fish using spears have to initially submerge the end of the spear to adjust their aim to the underwater distortion. Without submerging the spear first, stabbing into the water in the direction of the fish's image would cause you to miss the fish because that is not really where it is.
  21. Jul 30, 2010 #20
    Aside from the existence of multiple-star systems, the variety of stars of all ages and types, the differences in star variability to our sun's own cycles, the stars with planets circling them in systems that could never be mistaken for our own, the galaxies, nebulae, neutron stars, white dwarfs, and many other objects that bear no resemblance to our sun, etc, etc, etc...

    ...you seem to be imagining light being twisted around every which way as it goes through the universe. Light just doesn't behave that way. Space isn't like crumpled foil or oil or water. Photons from a distant source just passing the sun on each side are deflected so little that their paths don't cross for 500+ AU. Aside from the fact that the resulting image would be so smeared and distorted that it could never be mistaken for distant stars, it would require such tremendous concentrations of invisible mass in nearby space that the survival of the sun and solar system would be miraculous, which also raises the issue of why those masses haven't long ago coalesced into a single giant black hole. (after consuming us and our sun)

    The responses you've gotten aren't closed-minded rejections of something new. Your proposal is utterly at odds with observations of light's behavior and the appearance of the universe, while requiring things that appear impossible. There's no observational support for it and many severe problems with it.

    A more reasonable proposal is that the universe is large but finite in size, closed, and small enough that light can cross it multiple times, leading to multiple images of nearby galaxies being seen as progressively more distant ones. This could be investigated using computer searches for the patterns that would result, and IIRC some fairly detailed searches have been done, with no unambiguous signs of such patterns being found.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook