What we see now

The non amateur stuff. Hawking, black holes, that sort of thing

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Russell
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What we see now

Post by Russell »

Hi all,I would like to know when looking at distant stars the light takes millions of years to get to earth. How do we know they are still there.How can folks talk about this and that when it is not there.I would love to read a plain simple book that puts it into laymans terms.As you can tell by the question im very new to astronomy but cant get my head around the idea of reading a 20 million year old newspaper and that newpaper telling you whats happening today.When replying please keep it simple :oops: Thanks
Take care
Russell
joe
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Post by joe »

Hi Russell,

How do we know it is still there? We don't and we don't even know where there is! The word "now" only refers loosely to a small part of the universe that we can have influence over or be influenced by. If you look at something as it was 20 million years ago, now, you are not looking at the "now" of that object. You are looking at it then! Only the photons that entered your eye are here now. But on the other hand, reliable astrophysical theories will give us a good idea as to whether a star is at the beginning or end of its life and therefore whether it would still exist after 20 million years.

Taking your newspaper analogy, the date on the newspaper would not be today's, it would be 19,997,995 BC and would be telling you what happened then.

Even when looking at something happening across the street you are not looking at it now. It is removed from you by a distance and therefore the time-frame is different, admittedly by a miniscule amount , but we have chosen for the sake of survival to call everything that we see as happening now.

Was that simple? :?
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Russell
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Post by Russell »

Hi Joe,Thanks sorry for the delay in my reply.If i understand you correct we dont know nothing about what is happening at the present time or last week come to that.My point is that 100 years ago the the thoughts on craters on the moon,was that all could not be made by impact because most are round,But at that time people didnt know that any impact over 5 degrees to the planet or moons surface will cause a round crater.My point is if we dont know, how do folks come up with whats happening :?We laugh now at what people thought many years ago :!: Will folks laugh at the views now in 200 years time.
Take care
Russell
davep
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Post by davep »

Russell wrote:Hi Joe,Thanks sorry for the delay in my reply.If i understand you correct we dont know nothing about what is happening at the present time or last week come to that.My point is that 100 years ago the the thoughts on craters on the moon,was that all could not be made by impact because most are round,But at that time people didnt know that any impact over 5 degrees to the planet or moons surface will cause a round crater.My point is if we dont know, how do folks come up with whats happening :?We laugh now at what people thought many years ago :!: Will folks laugh at the views now in 200 years time.
It seems to me that you're confusing two types of "in the past" here. As Joe pointed out, when you look out into space, the further away you look the further back in time you look (this is your really old newspaper). The observations we make can serve a very useful purpose and we can learn from what we see. Now, from this, you seem to be saying that because we're looking into the past we can't know what's happening "today". You now seem to be suggesting that drawing conclusions from observations made today is akin to making conclusions based on ideas that were around a hundred years ago. That doesn't really work, that isn't comparing like with like; they're two totally different things.

When a team make observations of a distant object they don't draw conclusions about that observation and say "that's what is happening there right now, at this moment in time". That would be silly. However, what they can and do do is draw conclusions about the process we are seeing now. That's one of the nice things about the universe, it's terribly hard to create one in the lab but, because of the distances involved, you can look back to different periods in time and see various processes taking place.

Think of it like using CCTV footage to solve a crime. You don't watch Crimewatch on the BBC and assume that the footage you see is live and happening right now; you do, however, understand that it is evidence of somethig that did happen and that it still serves a useful purpose right now. Moreover, if that footage contained evidence of how a particular sort of crime were committed, while it wouldn't help you stop the crime that happened in the past, it could well help you prevent a similar crime from happening in the future. In the same way the evidence you gather from somethig happening really far away (really far back in time) might aid you in understanding why something not as far away (not so far back in time) is happening.

As for folks in the future laughing at us, I'm not really sure how you think that relates to your original question (perhaps you could expand on this), but one would hope not. The reason why? If the the "views" we hold now are proven to be wrong in the future then, hopefully, they'll be proven wrong using the same approach as the wrong views were arrived at. As such any rational person in the future will understand that based on the evidence available at the moment we'd drawn the best available conclusions -- if they've acquired evidence via the same approach that changes those views then a) they'll understand how our views were arrived at and how they were reasonable and b) they'll also understand that their views will be open to the same correction in their future.
Last edited by davep on Fri May 27, 2005 4:25 pm, edited 1 time in total.
Russell
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Post by Russell »

Hi Dave,i think you got me wrong or maybe i cant put into words what im trying to say :oops: What i mean is the things we think know now will change in the future.As i said in my first post im very new to Astronomy so this is a view of a novice trying to get his head around the greater picture.All i said was that folks years ago got it wrong and its is only because we are learning more we understand their mistakes and why they made them.So what i was trying to say is the Hawkins of this world might be the best in their field NOW, do make mistakes.My late father in law was in constant contact with Stephen untill his death and worked with him for 15 years.Ask Mr Hawkins if he is right,i know he will say he cant be 100% sure :lol:I have and have been reading their letters which mount to hundreds and all are way above me,but on reading them, both have changed their minds on what is happening.So if Stephen aint sure whats going on and he is the best in the planet,What makes you right :roll:
Take care
Russell
davep
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Post by davep »

Russell wrote:So if Stephen aint sure whats going on and he is the best in the planet,What makes you right :roll:
Sorry, I'm afraid I don't understand. What do you mean by "what makes you right"? What claim have I made that I insist is right (especially to a point that I'd insist I'm more right that somone who does this for a living)?

All I've written about is the obvious fact that knowledge and explanations evolve (something you seem to understand and agree with) and, as such, it's not really a revelation that, well, knowledge and explanations evolve. Is that something to roll your eyes at? If you think so perhaps you'd be kind enough to say what you think is wrong with that?

But, that said, I'm not sure how that really relates to what you first asked. You asked, in regard to distant stars, "How do we know they are still there". Myself and someone else have both pointed out that we don't know for sure that they are still there but that, more importantly, the issue of if they are still there is an unimportant point. What's important is that we know that they were there at the time that the light left them and that what you do see is important and tells you something useful. Are you disputing that? Do you think I'm "insisting" I'm right when I ask that?

Or, put another way, you gave the analogy that it's like "reading a 20 million year old newspaper and that newpaper telling you whats happening today". Myself and another have pointed out that the latter half of that analogy is mistaken. Do you dispute that? Do you think I'm "insisting" I'm right when I ask that? If so, perhaps you'd be kind enough to explain why?
joe
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Post by joe »

Hi Russell,

Will people laugh at wrong assumptions in 200 years? Well it's a possibilty, but unlikely for the simple reason that no scientist insists (in public anyway) that they are absolutely right. Each knows that scientific theories are there to be improved upon. I think also that progress would be very slow if everyone was too cautious, continually worrying about what other people think. It's right to do so but not to any extreme. Even I, as I get older and life gets shorter, bypass a few pleasantries to get to the point. I am always willing to apologise later if, or more likely when, I'm wrong 8)

Regards,
200mm Newtonian, OMC140, ETX90, 15x70 Binoculars.
Russell
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Post by Russell »

Hi what im saying is.We dont know ,and we will never know{in are livetime anyway}so what is right.Many folks have the gift of words some just think,please dont get me wrong BUT how do you know what you are talking about.as i said before many top people have got it wrong.if you are in that vein you must of got it wrong to.Why try to give it this and that it is all up to what i and you think.But if Stephen dont know, how can you tell me whats what.you tell me what you think but i asked a question and the thread as gone on.Just cause you can put your ideas into words better than me,am i wrong.What you seem to do is slag me off and say im wrong.If what i have said is wrong prove it.Stephen cant i just talked to him :wink:
Take care
Russell
Russell
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Post by Russell »

Well said Joe,Many folks talk PARC,read it backwards :wink: All im doing is looking and wondering.i was bought up with my father in law and i have questions to ask.I thought my father in law was shot away when i was young,how wrong i was.Maybe the questions im asking hurt them who are in the know,Why because they cant answer them.Many folks will come out with a long winded reply :lol: But can they say whats what no :wink: So lets all look and enjoy what we see.Its like any hobby you get them who enjoy ,then you get them who{ill leave it up to you} :wink:
davep
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Post by davep »

Russell wrote:Hi what im saying is.We dont know ,and we will never know{in are livetime anyway}so what is right.
We don't know what? What is it exactly that you're asking about?
Russell wrote:Many folks have the gift of words some just think,please dont get me wrong BUT how do you know what you are talking about
Sorry Russel, I don't understand what you're saying/asking here. I could be wrong but your tone seems to have become quite agressive and I'm not at all sure why. It seems important to you that I'm wrong about something but you wont actually say what it is you think I'm wrong about. Perhaps if you were kind enough to say what it is and ask me a direct question I could put your mind at ease?
Russell wrote:.as i said before many top people have got it wrong.
What is this "it" that they've got wrong?
Russell wrote:if you are in that vein you must of got it wrong to.
What must I have got wrong? What have I said that you think is wrong and you want me to admit is wrong?
Russell wrote:Why try to give it this and that it is all up to what i and you think.But if Stephen dont know, how can you tell me whats what.you tell me what you think but i asked a question and the thread as gone on.
Sorry, I really don't understand this. I've not "told you what I think" about anythig, I've simply tried to answer your question (that's what this sort of forum is about after all). I've made no bold claims, I've not said that I'm an authority on anything, I've simply said a few things about how conclusions tend to be drawn from observations of objects that are far away in space and, as you point out, a long time ago in time. Where is the problem with that? If you'd be kind enough to actually say what you've got a problem with in what I'd said then perhaps I can actually address it.
Russell wrote:Just cause you can put your ideas into words better than me,am i wrong.
Huh, where does this come from?
Russell wrote:What you seem to do is slag me off and say im wrong.
Ok, this is going too far. If you're going to make agressive accusations like this can you please at least quote where I've slagged you off. What's the point of asking questions and trying to enter debate if you're going to say this sort of thing about people who are kind enough to enter into debate with you?
Russell wrote:If what i have said is wrong prove it.Stephen cant i just talked to him
Perhaps if you could clearly say what it is you think you've said and I've said is wrong I could comment on this?
joe
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Post by joe »

Before this thread becomes too personal could I just add that of course no one can be absolutely "sure" of something, especially when cosmological concepts are involved but that does not mean we cannot comment on the subject. Some know more than others and there is a lot of evidence available for those who wish to study it.

The benefit of this forum is that in asking a question or making a comment we are inviting others, the knowledgable and the curious, to express their views as well. My experience is that here everyone gets a fair hearing. Everyone has their own style of Q&A and obviously it would be better to keep aggression to a minimum. I personally don't mind a bit of argy bargy but only if it is constructive.....and funny. :)

Best wishes,
200mm Newtonian, OMC140, ETX90, 15x70 Binoculars.
Cliff
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Post by Cliff »

Dear al
I have to agree with Joe on this one. We need to try to discuss things in a civil manner, even if we sometimes get get frustrated along the way. We all make mistakes, even Stephen Hawking is not 100% correct about everything. I myself recently made a bonkers suggestion about Saturn's Rings based a on a comment made by a professional astronomer on TV which I obviously totally mis-heard. Fortunately someone picked the matter up on this forum and I very quickly realised how stupid my idea had been. I can only say that on that occasion at least, I am very pleased that someone disagreed with me.
Funnily enough Russell mentioned that long ago no astronomers would have believed that lunar craters were caused by impacts. Well as it happens one of my friends, an amateur astronomer for many years, still holds the view that almost all the lunar craters are the result of vulcanism. I disagree with my friend completely, but we are still friends. On the other hand I have another acquaintance who holds very different ideas than myself on some other astronomical matters and I think it could be said, we pretty well hate each others guts. However, its not so much that chaps ideas I completely dislike, it's the way he seems to insist he is completely right.
Best wishes from the Grumpy Old Codger Cliff
Russell
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Post by Russell »

Hi all,I have read the above and we are all right or are we are all wrong.I dont mean to offend anyone but some just like to kick off.Im just saying what i think and thought that a forum was the place to say it.If some folks dont like what i say i will not post on this forum again.I know ive not got the gift of the gab,does that make me wrong.Cliff the not so grumpy old dos{think}has hit the nail on the head{thanks mate}so im just going to look at the Reiner gamma swirls on the MOON and wonder how they were caused.
Thanks Cliff & Joe folks like you make me stay in this forum.Dave get a life mate :lol:
Take care all
Russell
davep
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Post by davep »

Russell wrote:Dave get a life mate
Russell, would you be so kind as to explain the reasons for these highly personal remarks you've made about me? I see no need or reason for them.
Russell
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Post by Russell »

Hi dave,Get a life mate,you find that personal.Well if you find that hurts you i dread to feel how you think when you get your tax returns :lol: Come on just for the sake for the forum im sorry.Ps how many paragraphs will the reply be.Just look and wonder if you got any info on the Reiner gamma swirls i will be very instrested.
Thanks
take care
Russell
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