what is cosmological constant?Why it is introduced by Enstien.?
I do not want to stifle your "curiosity", but may I suggest that you learn ONE thing at a time?
You have asked a series of questions, and a number of people have responded to them already. Have you UNDERSTOOD these answers? Learning isn't a one-way, give-me give-me give-me situation. It requires constant feedback and interaction. Have you, on your part, put in ANY effort at trying to understand the question you are asking? Did you try looking at various sites, or even a text, FIRST before asking here? If you did, what did you read and what part did you not understand? Such explanation will help those trying to answer your question to better tailor their answers to address your particular problem.
If you wish that people put some thought and effort into responding to your questions, at the very least you should also show from your part that you have put some effort in trying understand it in the first place by putting a more elaborate explanation in your questions.
I thank you sir for giving me your suggestions.But as you said I don't make fun in seeing others responding me.Now only I got the oppurtunity to make use of this forum.As I have lots of doubts which my professors dont want to answer.I know that I am very low in knowledge.Yet in any way I want to acquire it.And from now onwards I will try to refine my approach of learning one at a time.Once again I sincerely thank you.You made me burst into tears.
No one can help you EFFECTIVELY if you do not reveal what you know and what you don't know. Your questions reveal little to none on this. Tell us what you tried to understand, and at what point you don't. That way, the explanation we give will START from where you understand and builds on top of that. This is the most effective means to understand anything.
And if a constructive criticism like that made you "burst into tears", you may have a very rough time in physics.
Separate names with a comma.