Listening to the Cries of Baby Stars

I had heard that some experiment was conducted in a very deep abandoned mine in UK to detect dark matter. Whatever happened to that experiment?

And what also fascinates me is that central to the theory of relativity is the constant speed character of light to all observers whether stationary or moving. What I am interested to know is why this assumption was made in the beginning i.e. what made scientists to think that speed of the light should be constant?

Akbar Sahib

Re: Proof of God

(Let me cut short my viewpoint.
Proving the existence of God on the basis of scientific evidences can be tricky, as laws and theories keep on changing. )

There`s an interesting story probably apocryphal. Diderot the French encyclopedist and rationalist was holding sway in Catherine the Great`s court and to her great consternation was converting people to atheism. To stop him she enlisted the support of Euler the great mathematician. He gave the formula, if I remember correct it is (x+n)^n/n= x hence God exists. Diderot who was notoriously bad at maths couldn`t counter this logic and had to flee the Russian Court.

Regards

#31
majumdar jii

Thank you for a very good response.

#32
Akbar260 sahib

Very good article. Please, keep up . Very informative, of course.

My knowledge of Astrophysics is pretty limited, more or less acquired from Stephen Hawking’s book. One thing I was not able to understand and would be grateful for some explanation here (no heavy duty tech jargon please)

Black holes don’t let anything not even light escape past event horizon. How do then they lose matter and decay?

A lot has been theorized about the existence of black holes. There are even some astronomical evidences as well like the Einstein`s cross. There must be continuous formation of black holes in the universe. Is it an ultimate end to the whole story of stellar evolution? Or the black holes might themselves be in a state of evolution. How might the black holes that were formed billions of years ago, be different from those which are forming now? How far does the theory about evaporating black holes bear weightage? If a black hole does evaporate, what comes out of it?

hameed:

how far is orion nebula and NGC-1398 from us?

is it Hydrogen fission/fusion which are the source for the light?

your article mentions about the stars, any idea about the planets? i.e. about their formation and demise.

lastly, what is our understanding about the death of these stars, do they end as black holes?

thanks in advance.

Re: # 35

{how far is orion nebula and NGC-1398 from us? }
Orion nebula is in our own galaxy and is roughly 500 light years away..so this is still in our neighborhood. In comparison, the center of our galaxy is about 30,000 light years away -- we are sort of on the out-skirts.

NGC 1398 is located roughly 50 million light years from us!

{is it Hydrogen fission/fusion which are the source for the light?}
Yes, hydrogen fusion is the source of energy for the stars. In fact, the ``birth`` of the star is denoted by the time it first starts fusing hydrogen into helium (and as result releasing tons of energy).

{your article mentions about the stars, any idea about the planets? i.e. about their formation and demise.}
We know that planets do form along with the planets. However, they are very hard to detect even for stars that very close by. There are planetary disks detected around some new stars in the Orion nebula - so we know that the planets will be forming around these stars - but we can`t say more than that.

{lastly, what is our understanding about the death of these stars, do they end as black holes?}
Well interestingly, the technique to detect young stars that I described in the article in mostly sensitive to stars that are much larger than the Sun. If a star contains 20 times as much mass as the Sun (or more), then we suspect that it will live less than 10 million years (in comparison, our Sun`s lifespan is in billions of years) and will leave a black hole. So many of the new stars seen in the NGC 1398 image will eventually leave as blackholes in a few million years. Amazing!!

-Salman

Re: # 37

``If a star contains 20 times as much mass as the Sun (or more), then we suspect that it will live less than 10 million years (in comparison, our Sun`s lifespan is in billions of years) and will leave a black hole. So many of the new stars seen in the NGC 1398 image will eventually leave as blackholes in a few million years. Amazing!! ``

how so???

shouldn`t a bigger star have more fuel i.e. hydrogen, to burn and last longer?

i read an article which said some millions (?) years later our sun will be out of fuel and start lossing its mass and become a white dwarf, which will also cause a loss of gravitatioanl pull. hence the entire solar system will go into a spin and the sun will disappear (turn into a black hole (?)).

but i also read that black holes have to much of gravity that it absorbs everything towards it (not even allowing light to escape) and hence the term ``black hole``. but if there is no mass how can there be gravity?
or can there be??

regarding your explanation that nebula orion is 500 light years away. if there is life somewhere in the entire universe and unless that civilisation/life can travel more than the speed of light, i think we won`t know its existence. hence there could be a life somewhere.

Re: # 39
The more massive a star is, more furiously it burns. Hence the very massive stars consume their hydrogen fuel far more rapidly, soon depleting it. Therefore, it is said that even if massive stars may be accompanied by planets, it is less likely that those planets might harbour intelligent life, if any life at all. We can expect more from average sized stars like Sun.
The ultimate demise of Sun does seem to be a white dwarf, but it is not necessary it will lose much mass. In fact, the dimensions of a white dwarf are planetary, but is is far far more dense, and massive. This fact keeps it somewhat alive.
There is a theory about `vacuum fluctuation`, which means that in space, particles and anti-particles keep on forming and annihilatiog in t=0, thus without disturbing the overall law of conservation of energy. This theory is, however, highly speculative. If the same occurs at the event horizon (the surface of the black hole), it is quite possible that the anti-particle may fall into the black hole, and the particle may escape. To an external observer, there might be a continuous stream of particles from the black hole, which, because of eating up anti-particles, would keep on losing mass. But this theory is more interesting than explanatory.
Thinking of reaching far off verges of the universe, at this time, seems as impossible as it was to reach Moon 150 years ago. So it is unlikely that we are in a position to comment that it is impossible to reach other galaxies. There must be life out there definitely, and there must be civilisations out there too. The Universe is so big. In future it might be possible to reach there without actually travelling THROUGH space...who knows!!

Dr. Muhammad Akbar Hussain Siddiqui
astronomer.zoomshare.com

Re: # 43

``There is a theory about `vacuum fluctuation`, which means that in space, particles and anti-particles keep on forming and annihilatiog in t=0, thus without disturbing the overall law of conservation of energy. This theory is, however, highly speculative. If the same occurs at the event horizon (the surface of the black hole), it is quite possible that the anti-particle may fall into the black hole, and the particle may escape. To an external observer, there might be a continuous stream of particles from the black hole...``

But this would mean black holes are directly observable whereas presence of black hole is speculated on the basis of its characteristic signature, much like dark matter . Another point.... what makes particle rather than antiparticle to jump out of event horizan?

Re: # 44
That is why I call this theory `highly speculative` and `more interesting than explanatory`.

There is a continuous piling-up of theories and speculations about black holes. It is because we cannot observe them directly. The black hole itself was theoretically discovered on a sheet of paper based on cosmological evidences and known facts. It is only when we might be able to observe them directly, we shall be able to judge what we had perceived correctly and what we didn`t. It would be like the nasty surprise of discovering life-forms like crustaceans and fish at the bottom of Challenger Deep (the deepest point of Pacific Ocean, some 11000m from the surface), when theoretically none should`ve been there, because of the extreme pressure. Much was visioned about Venus, but that planet turned out to be so different from what was initially thought. However, sound knowledge and calculations always help. Wasn`t Clyde Tombaugh doing the right thing, and looking at the right spot, to discover Pluto, based on calculations from Neptune`s motion?

Dr. Muhammad Akbar Hussain Siddiqui
www.astronomer.zoomshare.com

Re: # 45

{There is a continuous piling-up of theories and speculations about black holes. It is because we cannot observe them directly. The black hole itself was theoretically discovered on a sheet of paper based on cosmological evidences and known facts.}

I think you are absolutely right that we don`t know much about black holes. But I think they are on a far more solid footing than, say, dark matter. The theory is much more developed and we don`t know of a way of preventing a large star from becoming anything other than a black hole (i.e. its escape velocity is expected to be greater than the speed of light). Similarly, on the observational side, we know there are objects that have concentrated in such a compact volume that it cannot be any thing other than a black hole (from pure density-size arguments). However, how many kinds of black holes are out there, how they evolve over history, and whether they evaporate or not...well these are the big unknowns. There are plans being made for an X-ray telescope by 2025 that will be able to image the event horizon directly! Well...lets see what happens. Dark matter on the other hand is driven purely from unexplained observations, and theory has been developed to answer some unexplained anamolies. Unless astrnomers detect dark particles, there will be a huge question mark on it and there will always be a chance that it may disappear like the aether.

-Salman

Re: # 32

Smugness of some people is amazing. I thought the argument was over but no, these enlightened ones have to have the last word. The very first interact on this board dragged `Allah` in to discussion, I didnt!

At the same time I`d wish to apologize (in fact we all should) to Mr. Salman Hameed for messing up the discussion of such a beautiful article by him. Can we now start a more fruitful discussion about distant galaxies and interesting phenomena taking place out there?

Dr. Muhammad Akbar Hussain Siddiqui
astronomer.zoomshare.com

Re: # 33
Oh...absolutely no need to apologize - mine was a general comment.

Another general comment:
When working on a project we are always looking for things that are puzzling and cannot explain. This is the beginning of science and not the end of it. We do not ascribe an unknown to a miracle or necessarily the work of God. However, while searching for the answer, it is always assumed that the answer lies in the realm of the natural world, i.e. governed by the laws of nature. Even if we are unable to find the answer about a physical phenomena at present, we assume that the answer is not unknowable.

Thus, while trying to understand how stars form and how they die, the key questions deal with the state of hydrogen gas, its density, temperature, and pressure; nuclear physics of fusion, and radiation laws; and of course, gravity.

-Salman

Let me cut short my viewpoint.
Proving the existence of God on the basis of scientific evidences can be tricky, as laws and theories keep on changing. We can only be sure to deliver an exact comment on this issue when we know we have `completed science` at our disposal. We, of course, know this is not possible. We are exploring a universe with ever-growing complexity. We are only coming to know how less we know. The same goes to those who waste their efforts arguing that there is no God. We are, in fact, in no position to even comment on it.
I started this argument when a few readers added a point that there is no God, after reading the main article. That was a nonsense attitude.

Dr. Muhammad Akbar Hussain Siddiqui
astronomer.zoomshare.com