Happy Birthday Hubble

Via the Professor. This week saw the 19th anniversary of the launch of the Hubble Space Telescope – soon to be surpassed by the James Webb Space Telescope. The Hubble website essentials, rightly, name-checks Galileo Galilei, but a special mention should also go to one of Those [Royal Society] Guys, Robert Hooke – “Tis not unlikely, but that there may be yet invented several other helps for the eye, as much exceeding those already found, as those do the bare eye..” Telescopes, eh? And, as Douglas Adams said, “Space is big. Really big. You just won’t believe how vastly, hugely, mind- bogglingly big it is..”

, , , ,

  • joeCanuck

    Mind boggling, ain’t it.
    Keep it up, Pete.
    Those late 17th and early 18th century Royal Society guys were amazing. I still find it incredible what they achieved with what they had. Imagine if they lived today. Poor Robert doesn’t get the respect he deserves; politics – spit.

  • Ulsters my homeland

    Pete, is it true that astrologers use the geocentric model in their calculations?

    Is there a universal unit of time – ie could the SI second be considered one? or do you think time should always be calculated from the planet you reside on – ie years, months, days, hours, ?

  • Pete Baker

    UMH

    Who cares what astrologers use? It’s just another anti-scientific application. One that they’ve chopped and changed as more knowledge has become available.

    And, on Earth, the SI unit of time has long since moved away from a planet-centric measurement.

    The only way I can see your question about a universal unit of time making any sense, in a scientific context, is if it were to be applied solely to how we, or any other life-forms, experience time.

  • Ulsters my homeland

    On the universal unit of time, that is exactly how I was thinking about it, using the cesium atom second ( as it’s the same as our second) for planet hopping.

    However, as we humans invented the second through natural methods (the stars/moon), and then refined the dicision of time through our undersatanding of numbers, does using the atomic clock now sound the best way to approach time if living on a different planet? Considering that our body clocks will adapt to our new planet, will the SI second be needed?

    hope you get what i’m querying as it’s not that easy to write down 😀 what I’m really getting to, is universal time (like the SI second) actually practical when living on othe planets?

  • joeCanuck

    UMH,

    You raise an interesting philosophical question. Does time actually exist? Personally I simply believe that time does not exist without a conscious observer. At its simplest, time is just an experience of change. We, or something else, notice that a change has occurred and interpret that as “time” having passed. If there was no change, there would be no concept of time having passed.

  • Pete Baker

    I think I know what you’re getting at, UmH. But it’s just not relevant.

    “will the SI second be needed?”

    A SI second will continue to be needed as an universal [for now human] measurement for scientific research.

    How humans on other planets might experience days, months, years, is an entirely separate discussion.

    If other life-forms have different standards of measurements then those bridges will be crossed should they occur.

  • Ulsters my homeland

    joe, I would actually say time does exist naturally – ie, the rotation of the earth sets time (days+nights). Time is also set yearly by the setting of the sun. It’s the division of the natural time (days into hours – hours into minutes) which I wonder does it really exist, or is there a natural basis for it too, as in the discovery of the SI second?

  • joeCanuck

    UMH,
    I hear what you’re saying but if there wasn’t a conscious observer, who, or what, would know about the sun setting or rising?
    With regard to clocks measuring actual “time” they are simply human constructed artifacts. If we had clocks that didn’t have outputs, via hands or digital displays or whatever, could we use them to measure “time”.

  • Ulsters my homeland

    [i]With regard to clocks measuring actual “time” they are simply human constructed artifacts. If we had clocks that didn’t have outputs, via hands or digital displays or whatever, could we use them to measure “time”.[/i]

    see the points on si seconds. Humans discovered it existed only after we invented it through different methods. That’s more than a coincidence to me!

  • joeCanuck

    UMH,
    I think you are mistaken. No üniversal “second” has been discovered to my knowledge. It, the SI second, is another human construct.

  • Ulsters my homeland

    joe, I was basing it on the link that Pete gave which says “refers to a cesium atom in its ground state at a temperature of 0 K”

    I thought that was as natural as it got, maybe Pete could shed more light on it.

  • joeCanuck

    UMH,
    I’ll let Pete comment.
    Interestingly, despite what I have said, there could be a theoretical universal unit of time.
    Some theoretical physicists have speculated that space may be quantizized. In other words, there is a minimal length of “unit” space. If that is correct and we accept that the speed of light is constant in a vacuum as postulated by Einstein, and which experiments seem to support, then a universal unit of time could be calculated as the time that light takes to traverse that distance. We still have the problem, of course, of “finding” a “clock” to measure that “time”. We’re back to human, or other, engineers to construct some sort of measuring device.

  • Ulsters my homeland

    I get your point about si being manmade.

  • Ulsters my homeland

    Joe, interesting stuff about ‘unit’ space. That clock would be the key to the movement of the heavens.

  • joeCanuck

    UMH.
    Indeed. But I view clocks as a double edged sword, unfortunately. They have enabled us to gain great insights into the workings of nature and have been indispensable in some technical fields which make life better (well, easier), GPS, cellphones and the like. But they have also been instrumental in enslaving most of us; think timeclocks at work. Happily, I’m now retired and I never wear a watch except when I’m on holiday and may have a bus, train or plane to catch.

  • Ulsters my homeland

    Are there systems in the universe where a star[s] revolves around a planet[s]? or are all systems, solar systems like our own?

  • joeCanuck

    UMH,

    If you take a two body orbiting system, say a sun and a planet, they both actually orbit about their common, (mathematically calculated), centre of gravity. This is what really happens with the earth and moon. But if one body, the star, is much more massive that the other, that centre of gravity may be inside the radius of the star so it’s more convenient to describe the smaller body as orbiting the larger one. When it comes to even a three body system, however, although the same principle applies, the experts have not been able to construct an equation to predict the movements. So, for example, it’s not known to be impossible for one our planets orbits to become unstable in the future resulting in one or more being “ejected” from our solar system
    Incidentally, a large percentage of the stars we see are actually binary stars. The brightest star in the sky, Sirius or Dog Star close to Orion’s heel is one such pair.

  • Ulsters my homeland

    why are sunspots cooler in the centre if the sun’s core is supposed to be the hottest part?

    How did the theory come about that the core is the hottest part, when we haven’t proof if it’s centre? was it because the sun is supposed to have a gravitaional pull related to it’s mass, and this is why the centre is supposed to be the hottest?

  • joeCanuck

    The core temperature is thought to be around 15 million degrees K. That was first calculated (roughly estimated) back in the late 19th century based based on the heating effect on the earth. The number has been revised many times since because of the increase in our knowledge, discovery of radioactivity and nuclear reactions for example.
    As you suspect it is indeed caused by the enormous density.
    Interestingly, althougth the surface is around 6,000 degrees, up above the photosphere the temperature can be 25,000 degrees. I’m not sure that anyone has come up with a definitive explanation for that and there may still be several theories kicking about.
    Sunspots are caused by intense magnetic activity which inhibits convection currents around them and a slight cooling. Their temperature is still pretty hot, around 4,000 degrees.

  • Ulsters my homeland

    Joe, you certainly know you stuff fella.

    I always thought sunspots were depressions on the sun’s surface. If so, when we see the centre of the spot we might actually are seeing further into it’s core. Is it possible that the core is actually cooler than the surface plasma?

    also, is it sound to suggest that the sun is a certain weight because of it’s mass, even when we don’t actually know what’s at it’s centre? It’s interior could be simply gas and the outer could be plasma?

  • joeCanuck

    The sun doesn’t have weight as such, just mass. Weight is the force exerted on a mass by the local force of gravity. That’s why an equivalent amount of matter (mass) only weighs a sixth as much on the moon as on the earth. The moon’s force of gravity is that much smaller.
    The core cannot be cooler because it is known that you need an extremely high temperature for the fusion of hydrogen nuclei into helium atoms. That’s what makes the beast so hot.

  • Ulsters my homeland

    “[i]The core cannot be cooler because it is known that you need an extremely high temperature for the fusion of hydrogen nuclei into helium atoms. That’s what makes the beast so hot.”[/i]

    why is the heat thought to occur from the core? should the plasma on the surface not be enough?

    if the suns core is largely hydrogen and this is where everything is condensed to form the gravitational pull and heat needed, shouldn’t we expect it to spin much quicker?

    also, the study of Heliosesmology has revealed the sun vibrates like a bell, but a dense centre is not supposed to be a good candidate for oscillators. How does the sun vibrate like a bell if it’s centre is dense?

  • joeCanuck

    UMH,

    I’m just come in from sitting in the sun; it’s a glorious spring day here, temperature 25 C.

    I’d have to refer you to the Standard Cosmological Model for a full description. But if you think of the simplistic Ideal Gas Law, P.V. = nRT, as gravity causes a gas cloud to contract, the pressure rises. The volume does contract but cannot decrease indefinitely due to forces between the atoms/molecules (Please don’t ask me to explain neutron starts or black holes; that’s beyond me). So the temperature rises. Eventually the temperature gets so high that nuclear reactions start and the star “ignites”.

    With regard to dense objects not be able to ring very well, here’s a thought experiment you can try.
    Take a fairly dense object such as an iron bar and suspend it from a string. Then also take a much less dense object, say a rolled up newspaper and suspend it alongside the iron bar. Hit both with a hammer. Which one rings, i.e. oscillates?

  • Ulsters my homeland

    thought experiments? …..isn’t thought experiments the problem?

  • joeCanuck

    OK; do it for real and be sure to let us know the result. ;0)