Ask Me Anything! (about science)

I’m trying to think of as many topics I can to cover in both the pages and the posts. But I can’t think of everything, so if you have any questions please send them to me! The best way to do this is through the blogs facebook page. Any and all questions will be considered.

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  1. Maddie

     /  29/09/2012

    Do you know why the Earth’s atmosphere doesn’t affect the Hubble Space Telescope…?

  2. Maddie

     /  29/09/2012

    Sorry- it might be a bit of a basic question for you!

    • Not at all! This blogs about explaining the basics to understand the harder stuff. I just need a bit more detail about the question, do you mean why doesn’t it fall to earth because of gravity? or something else?

      And thanks, you may have given me the kick I needed to get this project going again.

      • Maddie

         /  20/10/2012

        I meant, why does the Hubble get such good images compared to the telescopes on Earth? What’s so special about it? (Sorry for the late reply!)

  3. That’s actually a pretty good question! One way to explain it is by thinking about what images look like when the photo is taken through water. The water bends the light and distorts the image, so while we get some pretty cool effects, it’s not very accurate. The same happens with the earth’s atmosphere. Varying atmospheric content acting at various different temperatures interfere with light as it comes towards the earth. Some photons may get absorbed whereas others could simply distort like with water. Either way we end up with an inaccurate and possibly even messy photo!

    So to avoid this problem we put telescopes in space (like the Hubble) where there is no atmosphere and therefore no interference. This may sound menial, but when light has travelled a billion years or so to be here even the slightest interference can drastically change its properties. Couple that with the idea that we are looking at something that is so far away, and therefore visually small, that often it is invisible to the naked eye.

  4. Swarup

     /  18/12/2015

    I have a question about vision, and I note that you have made some posts about vision so if the answer to this question is to be found amongst those, you can refer me to the relevant one. My question concerns not so much the process of what happens after light enters the eye, but rather how it is the case that the light entering the eye contains information about the objects we see. I understand that light is emitted from a light source– say the sun– and that this light then reflects of objects in the environment and enters our eyes. But, to take an example of a tree, the tree is one thing, and the light that reflects off of it is another entity altogether. How does light that reflects off a tree, contain visual information about that tree? It is simply light which has reflected off of a surface. One may explain how based on the color of the tree, the reflected light will provide information about the tree’s color: some of the light will be absorbed by the tree, and some reflected off the tree. I have distant recollection from my school days that which parts of the ROYGBIV color spectrum get reflected and which absorbed, is determined by the color of the tree itself. So I accept that light reflected off a tree will contain information about its color. But the shape and form of the tree– how does the light which gets reflected off the tree and then enters our eye, contain information about the the shape of the tree? In short, aside from color, all the other visual information we get about the environment around us– how does reflected light contain that information?

    • Nice question Swarup.

      The problem you have is in trying to see light as conveying information about shape and everything else other than colour, it doesn’t. Visible light only transmits information about colour to our retinas (the part of the eye which detects light).

      Each photon, or ray of light, hits a single cell within the retina and this will cause a chemical reaction which “activates” the cell, causing a signal to be sent to the brain saying that a some light has hit this single cell. As far as your brain is concerned this is like a single pixel appearing on a TV. It gives us some information, but there is so little information it is nearly useless.

      Thankfully our retina does not have only one cell, it has millions of cells for this purpose. each ray of light hitting the retina carries a different colour depending on what it reflected off. Our brain then does the amazingly complex job of putting all these signals together to form a coherent image.

      So the brain forms the image, not the light. The rest is down to our learning. There is evidence to suggest that we actually have to learn to detect shapes, distances, textures and everything else we can ascertain from our vision. To a newborn vision means very little except something interesting. It is only as we come into contact with objects and spend more time looking a things that we learn to differentiate between different things and recognise them as objects of interest.

      So in short, it’s nothing to do with light, but everything to do with the brains ability to piece together an image and then learn from it.

  5. Swarup

     /  08/04/2016

    Thank you Nick for the extremely thought-provoking reply. I must apologize for the delay in my own reply as I shortly thereafter left for an extremely rural location off the internet grid for 4 months.

    If I understand correctly from your explanation, all the eye is able to perceive is color. The eye contains millions of color-sensing cells, which upon perceiving color then transmit this information to the brain. And the brain then processes this information to form actual images of all the objects we see around us. Amazing! But the question I have is, how such a thing is possible with only color information? Where does one object end and the next begin? How is a shape determined? Once shapes are determined, I can imagine how our stereo vision gives the ability to discriminate depth and distance; but such discrimination is all secondary i.e. comes after the initial massive job of perceiving shapes from the color information the eyes provide. And this latter remains a mystery in my mind. You intimate that a newborn cannot do it as this is a learned skill. Ok, but on what basis is this skill acquired? How does color provide adequate information for the discrimination of objects in the environment?

    • Yes, in a manner of speaking all the eye really detects is colour, more specifically photons.

      The brain is smart enough to do the rest, separating sections of colour into distinct objects. this is largely done by being able to distinguish between edges of items, contrast between certain colours. This is on the edge of my expertise so I can’t go into too much detail. what I can say is that our ability to define objects in our vision is, to some extent, a learned skill.

      For example, babies are well known to be very bad at distinguishing between colours at first, and need extremely vibrant and large contrasts (starting with purely black and white) for them to be able to notice and pay attention to an object. This matures with age.

      There have also been studies done on cats where as kittens they are restricted to only seeing a limited range of shapes (e.g. vertical stripes). when tested later the findings suggested that the cats had trouble distinguishing shapes which differed from what they had been exposed to (e.g. they could see vertical stripes, but not horizontal stripes). An example paper is here:

      These studies have actually proven that there are neurons in the visual cortex in the brain responsible for things like the directions of lines. Put enough of these neurons together when they fire and you get a shape. Of course any distinguishing contrast between two colours becomes a line so this would be part of how we see shapes.

      It is also why camouflage is very effective as you blur the lines between colours.

      One thing however, which is not learned – or at least not at a level I am aware of – is the ability to detect motion. Motion is an easier way for us to define what a shape looks like as we can constantly compare it against a steady backdrop. But motion is processed in an older part of our brain (evolutionarily speaking). It is done below the level of our consciousness to the point that sudden motion can be very distracting to us (an advantage when considering predators who may attack us). This is what will normally render camouflage useless. But more interestingly, being a more primeval part of sight, some blind people can still sense motion, as they have only damaged the part of their brain dedicated to building the image we see, as opposed to the part which detects movement (this is called blindsight).

  1. Questions about Science | Science Defined

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