Here are the answers to yesterday’s science quiz:

Albert Einstein, 1920.

Albert Einstein, 1920.

  1. You know that light travels at a speed of 1 light-year per year, don’t you? You also know that the universe is 13.5 billion years old? Okay, if you’re so smart, how far away is the farthest object we can see in our telescopes?

    45 billion light years. (13.5 billion years ago it was closer, but then the universe started to expand.)

  2. When Gregor Mendel started experimenting with how organisms inherited characteristics he started with mice. What made him switch from mammals to peas?

    His bishop said (rough translation), “Mice? You want to breed mice and have them copulating all over my monastery? Not a chance! Stick to plants, Gregor!”

  3. In what way did the outbreak of World War I in the summer of 1914 save Albert Einstein’s reputation and clear the way for acceptance of his relativity theories later on?

    Einstein’s theories were scheduled to be put to the test in August 1914, when a crucial total solar eclipse could be observed in the Crimea. The outbreak of war made those observations impossible.

    Then Einstein, regretfully looking over the calculations of the displacement of stars close to the sun that were now useless, realized with horror that he had made a mathematical mistake. His results were all wrong. If the observations had been performed his paper would have predicted false positions for both the stars and his professional credibility.

    He redid the calculations in time for the actual observations, and then the results were just as he had said they would be.


  1. Bill Goodwin says:

    Allowing meself a wee smile…

  2. TonyC says:

    you said farthest object we can see in our telescopes?

    I don’t think we can see to the limits of the ‘visible’ universe in our telescopes… yes, that is the largest potentially visible distance, but we don’t have perfect resolution or sensitivity! the ‘best’ telescope right now is still Hubble, which imposes an upper limit on ‘visible’ based on apparent magnitude and our estimate of ‘brightest stellar object’.

  3. Rory Kent says:

    Aww.. I’m sad now.

  4. Brenda says:

    1. What we can see in our telescopes is what the object looked like 13 billion or so years ago. Who knows how far away the object we can see in our telescopes is today, or even if it still exists? As was pointed out elsewhere recently, our Sun could vanish, and Earth would circle the spot where it once was contentedly for another eight minutes.

    2. Plus, Mendel’s simplistic model of inherited characteristics works less well for mice.

  5. Alan says:

    Ok, reading the answer to #1, I know have a question.

    Assuming the universe is 13.5 billion years old, and assuming that everything was “much closer” 13.5 billion years ago, how can the most distant object be 45 billion light years away?

    If nothing can travel faster than the speed of light, one would think the maximum distance between objects which were once “close” 13.5 billion years ago would be 27 billion light years… ?

    I am sure there must be some complex relativistic explanation which will completely fly over my head, but maybe not.

  6. Art says:

    @Alan: Because in addition to the objects actually moving, space itself is expanding which also increases the distance between objects.

  7. David Ratnasabapathy says:


    As I understand it, Space can expand faster than light. The further away we look, the faster the universe expands. A region of universe sufficiently far from us would expand faster than light. Objects embedded in it would be carried along.

    ‘Starts With a Bang’ has a nice explanation with pictures:

  8. CaitieCat says:

    Alan, it’s got to do with the universe expanding. Every bit of matter in the universe is moving away from every other one. To get an understanding of that, imagine drawing three dots on a balloon. When you blow the balloon up, each of the dots will move away from each of the others. Same thing’s happening to the universe, basically, so it’s not just 2x the time, but some additional factor to allow for universe expansion.

  9. Brenda says:

    Well, clearly not every bit of matter in the universe is moving away from every other one. My fingers are rapidly coming closer to my keyboard as I type. Also, as a galaxy we’re headed for a collision with the galaxy in Andromeda, and the Milky Way has already swallowed a half dozen minor galaxies and the two Magellanic Clouds will be swallowed by us at some point.

    It’s this that makes it so hard to know the current state of something we can only see billions of years in its past. Maybe some sort of gravitational interaction is sending it TOWARD us now!

  10. Gerry Quinn says:

    The main reason for the seeming paradox is that in general relativity it is possible to define ‘now’ somewhat arbitrarily. The usual coordinate system used is ‘comoving coordinates’ in which the galaxies, which are flying apart, are all considered to have unchanging coordinates. Naturally, in a universe described in such a fashion, space is expanding, as things whose spatial coordinates do not change get further and further apart as time goes on.

    If we used a different coordinate system we would get different results.

    Space isn’t a “thing” that sits between the galaxies pushing them apart, like the rubber does on the spotted balloon.