coldel Posted February 9, 2018 Share Posted February 9, 2018 Yes its effectively time travel, that we see things from many years ago, looking into the past. It really blows the mind to imagine that you are looking back in time as well as looking across the expanse of space. That in say 10000 years time another form of life could be looking in our direction and seeing our sun which might not be there and we are long gone. Link to comment Share on other sites More sharing options...
davey_83 Posted February 9, 2018 Share Posted February 9, 2018 How is this distance even worked out? Link to comment Share on other sites More sharing options...
Jetpilot Posted February 9, 2018 Share Posted February 9, 2018 So they might not actually still be there? Link to comment Share on other sites More sharing options...
Jay84 Posted February 9, 2018 Share Posted February 9, 2018 Found this, its fascinating: The light-year is a unit of length used to express astronomical distances. It is about 9.5 trillion kilometres or 5.9 trillion miles. As defined by the International Astronomical Union, a light-year is the distance that light travels in vacuum in one Julian year. Because it includes the word "year", the term light-year is sometimes misinterpreted as a unit of time. Which led me to this: Yes, there are many stars in the night sky we see that don't exist right now. Light travels extremely fast, at 300 million miles per hour, but even at that speed it may take many thousands or millions of years for it to travel and reach far places. For example, light from our Sun takes 8 minutes to reach Earth. Link to comment Share on other sites More sharing options...
coldel Posted February 9, 2018 Share Posted February 9, 2018 4 minutes ago, davey_83 said: How is this distance even worked out? By very clever people who understand physics much more than we do! Fact is that until we solve the survival challenge of space we rely on these sort of vessels to go explore on our behalf, it must be exciting and frustrating in the same instance that you have to wait years to see the fruits of your labour but when you see something no one has ever seen before... 1 Link to comment Share on other sites More sharing options...
coldel Posted February 9, 2018 Share Posted February 9, 2018 7 minutes ago, Jetpilot said: So they might not actually still be there? Yep, could be looking at the past, something which disappeared. Link to comment Share on other sites More sharing options...
ilogikal1 Posted February 9, 2018 Share Posted February 9, 2018 1 hour ago, davey_83 said: How is this distance even worked out? With a really long bit of string... 1 Link to comment Share on other sites More sharing options...
davey_83 Posted February 9, 2018 Share Posted February 9, 2018 So are clever scientist people measuring the distance to the star or to the light emitted? All we can view is the light from the star that's traveled years and years, so how do we know how far it's traveled from if the light source is unknown? I call BS, oddly all the constellations are exactly the same as when man first looked up at the night sky and began to take note. 1000's of years laters and they're all still exactly the same even though our sun is traveling though space at just over half a million miles an hour. Link to comment Share on other sites More sharing options...
Stutopia Posted February 9, 2018 Share Posted February 9, 2018 3 minutes ago, davey_83 said: So are clever scientist people measuring the distance to the star or to the light emitted? All we can view is the light from the star that's traveled years and years, so how do we know how far it's traveled from if the light source is unknown? I call BS, oddly all the constellations are exactly the same as when man first looked up at the night sky and began to take note. 1000's of years laters and they're all still exactly the same even though our sun is traveling though space at just over half a million miles an hour. When contemplating changes in the observed universe during the time of humans, you should consider that if the history of the universe is the size of a football pitch, then all of human history is an area the size of your hand. Link to comment Share on other sites More sharing options...
davey_83 Posted February 9, 2018 Share Posted February 9, 2018 And you know this how? Link to comment Share on other sites More sharing options...
ilogikal1 Posted February 9, 2018 Share Posted February 9, 2018 Because of the string. Obviously. 1 Link to comment Share on other sites More sharing options...
coldel Posted February 9, 2018 Share Posted February 9, 2018 52 minutes ago, davey_83 said: So are clever scientist people measuring the distance to the star or to the light emitted? All we can view is the light from the star that's traveled years and years, so how do we know how far it's traveled from if the light source is unknown? I call BS, oddly all the constellations are exactly the same as when man first looked up at the night sky and began to take note. 1000's of years laters and they're all still exactly the same even though our sun is traveling though space at just over half a million miles an hour. Because its simple maths if you try. You can look at a position in the sky of a star, then say half a year later look again (yes they are in different positions) and you have three points and simple trigonometry allows your to triangulate distance. Clearly the further away something is the less the angle so it becomes impossible as the distance the Earth rotates the sun is not big enough to make the angle sufficient to measure difference, thats when colour spectrums and brightness come into play. But in terms of distance, apparently it would take hundreds of millions of years for the sun to complete a single orbit of the galaxy, so the constellations havent moved in a 1000 years, well of course not, we have a long way to go. It really isn't that hard to believe, drive your car through a tunnel and hear the noise bounce off the walls, its energy and it moves and it takes time - light is an energy just like sound is you just need to use established and proven ways of measurement at a larger scale. Given that the planet has been around for millions of years, stars having not moved in say 1000 years is quite sensible (that said 1000 years ago there was not the technology to accurately place stars in the sky) if you move a marble on a table 1mm over the course of a year it will look like its in the same position. Link to comment Share on other sites More sharing options...
davey_83 Posted February 9, 2018 Share Posted February 9, 2018 (edited) Yes but are we looking at the travelled light or the star itself? I knew about the trigonometry, but not the colour spectrum. I'll have to read up on that. Brightness of an object doesn't initially tell one it's distance surely? Tbf I do love astronomy but we seem to impose so many assumptions. For example the d wave quantum computer is said to operator a much lower temperatures than anywhere in the universe? Yeah OK Edited February 9, 2018 by davey_83 Link to comment Share on other sites More sharing options...
coldel Posted February 9, 2018 Share Posted February 9, 2018 No assumptions on brightness and distance, its all doable here on planet earth turn on a light and measure the time in another position. I would imagine its clear that the further a light is away the harder it is to see. the less bright it is and the longer it takes to travel. So yes you measure how far light has travelled and I would say you assume there is a light emitting entity at the source which has fired off energy which has a destination which is where the telescope picks it up. Which isn't a daft assumption as again you can easily replicate here on earth. Clearly drastic changes in density can refract light and bend light (black holes?) which increases or decreases its brightness and thus distance but you have to drop that into the calculation, but a calculation that gets 99% right is still as good as anything and could be 100% accurate in the absence of abnormalities like black holes between us and the light source. Link to comment Share on other sites More sharing options...
valy Posted February 9, 2018 Share Posted February 9, 2018 the main downside to all the above is that there is no 'warp' travelling and takes an eternity almost for things to happen ... 1 Link to comment Share on other sites More sharing options...
davey_83 Posted February 9, 2018 Share Posted February 9, 2018 (edited) You can have a two suns, one twice as bright as our sun (this forumla has a name) and the other incredibly bright like 100's brighter than our own sun. I'm pretty sure the brighter sun can be twice as far away and yes still appear brighter than sun a) therefore sheer brightness has nowt to do with measuring distance IF you don't know the exact point of source. Your example of turning on the light to measure speed, works because you know the positions of both point a and point b in a room/environment. Edited February 9, 2018 by davey_83 Link to comment Share on other sites More sharing options...
Stutopia Posted February 9, 2018 Share Posted February 9, 2018 1 hour ago, davey_83 said: And you know this how? Same way anyone knows anything. It's what the bulk of evidence currently at our disposal supports. Link to comment Share on other sites More sharing options...
coldel Posted February 9, 2018 Share Posted February 9, 2018 16 minutes ago, davey_83 said: You can have a two suns, one twice as bright as our sun (this forumla has a name) and the other incredibly bright like 100's brighter than our own sun. I'm pretty sure the brighter sun can be twice as far away and yes still appear brighter than sun a) therefore sheer brightness has nowt to do with measuring distance IF you don't know the exact point of source. Your example of turning on the light to measure speed, works because you know the positions of both point a and point b in a room/environment. You are assuming only one point of reference. We can measure the brightness of the sun, relative to our position, we can then compare this to other stars moving outwards and generate multiple points of reference and extrapolate outwards. Size, brightness and anything in-between dictates distance and again is all provable (and has been and you can do it yourself if you doubt it with some simple experiments) your assumption that we are just measuring distance between two points is false from the offset. As with anything you need 'three sticks in the sand' to see trends and distance and mapping outwards lets you do this. 1 Link to comment Share on other sites More sharing options...
glrnet Posted February 9, 2018 Share Posted February 9, 2018 9 hours ago, StevoD said: When you post in a thread and realised you missed a @*!# storm last page And realise your reputation will look like potentially poking the fire. We've all mellowed!! Link to comment Share on other sites More sharing options...
davey_83 Posted February 9, 2018 Share Posted February 9, 2018 (edited) Again I don't see the correlation between brightness and distance of stars. A dull star can be close and a brighter star far away, the brightness won't tell you a thing about distance. Again I call BS on the lot, reason its nowt but guess work. If we went thru space on a actual elliptical circle then maybe, but from what I gather it's more like a stretched slinky being dragged along by the sun's gravity. In which each 6 months allows us to make use of 186 million miles of diameter, IF it were a perfect circle but it isn't even. If you've done any of this simple light measurements yourself, I'd be mightly impressed. Edited February 10, 2018 by davey_83 Link to comment Share on other sites More sharing options...
coldel Posted February 10, 2018 Share Posted February 10, 2018 You are entitled of course to call it - there is a lot of study by thousands of independent people on the same subject all coming to a similar conclusion, a quick google brings up this as the first result, have a read. https://www.space.com/21640-star-luminosity-and-magnitude.html Measuring the speed of light at home, using a microwave and a chocolate bar https://www.youtube.com/watch?v=kpB1wezpJeE You can also do it using a light source, two mirrors one stationary and one rotating, to measure the speed of light as done by some French guy in the 19th century way before computers were around. I guess you are either in or out, but there are so many ways of measuring it from pinging websites along fibre optic cables to looking at Jupiter (how it was first done). Link to comment Share on other sites More sharing options...
Zeezeebaba Posted February 10, 2018 Share Posted February 10, 2018 A difference in opinion is the driving force in discovering new things. I particularly liked the study on the rate of universal expansion based on stars going nova. They said a nova is a cosmic constant regardless of star type. I'm lot a physicist but have an interest in all of this and find it fascinating. Every day brings a new discovery and thats living I do feel a little sorry for those basing their lives on Internet propaganda that supports their viewpoint on the earth being flat or us not going to the moon, believing in deities etc. All I know is this, if the planet was run by scientists and not politicians it would be a much less stressful place and in better condition than it is now! 2 Link to comment Share on other sites More sharing options...
Jay84 Posted February 10, 2018 Share Posted February 10, 2018 Yeah its fascinating...I just lack the knowledge that Coldel and Davey have to participate in the discussion. But am enjoying reading it. I too don't believe the earth is flat. 2 Link to comment Share on other sites More sharing options...
Stutopia Posted February 10, 2018 Share Posted February 10, 2018 Love the chocolate experiment @coldel Link to comment Share on other sites More sharing options...
davey_83 Posted February 10, 2018 Share Posted February 10, 2018 Jay84 I have no knowledge believe me, only saying what seems odd in my ickle mind. I've not questioned the speed of light or how it's measured. I was looking towards working out these great distances from the observation of brightness, which doesn't make sense. 19 hours ago, coldel said: Size, brightness and anything in-between dictates distance and again is all provable Google says: The idea of the ladder is to start with nearby objects like stars. We can measure their distances using a method called parallax. Back in the 90s a satellite called Hipparcos used parallax to measure the distance to thousands of stars. Once you know how far away a star is you can calculate how bright that star is. Now I'm confused, you say brightness dictates distance, however it would seem you need to know the distance first? Link to comment Share on other sites More sharing options...
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