[aazaya]

Why doesn't time runs back?
How does the force such as gravity form?
Is the feeling of laugh and cry only in animals or plants also have feelings?
why do we feel unsafe at night but we feel safe at same place in day?
we drink water but what is the element that save us?

[ajb]

aazaya, on 27 January 2012 - 10:57 AM, said:

Why doesn't time runs back?

We don't really know.

You should look up the various notions of "the arrow of time". You should also look up Closed Time-like Curves, or CTCs in general relativity.

aazaya, on 27 January 2012 - 10:57 AM, said:

How does the force such as gravity form?

Our best understanding of gravity is general relativity. The idea here is that gravity is not really a force as such but due to the local curvature of space-time.

[Jiggerj]

aazaya, on 27 January 2012 - 10:57 AM, said:

Why doesn't time runs back?

I'm still not convinced that time is weaved into the fabric of the universe. Whenever I read of someone referring to time, what I see is actually a reference to energy being burned. If someone says it takes an hour to drive their car to another city, what I hear is that it takes a gallon and a half of fuel to get to another city (say, fifty-five miles).

I've heard it said that the closer people get to travelling at the speed of light, their aging process slows; this is somehow proof that time is being maniulated. I don't see it. It is merely proof that the the process of decay slows the closer one gets to the speed of light.

Then again, I don't see a PHD certificate hanginng on my wall either.

[immortal]

aazaya, on 27 January 2012 - 10:57 AM, said:

Why doesn't time runs back?

There is nothing in physics which indicates that time flows forwards either, time neither flows forwards nor does it flow backwards and we really don't know whether there is an arrow of time physically or not.

When you asked this question it reminded me of an article which I gave to my college magazine where I had mentioned about the possibility of time flowing backwards and I read that article again and I was very embarrassed for the wrong conclusions that I had made in that article merging the mystical view of precognition and the scientific speculation of time flowing backwards made by few physicists. I was young and didn't knew how most of the science works at that time and therefore I am very disappointed that I pushed such a non-scientific issue in my article. However I think it was this link which made me to speculate on such a thing.

Future Influence: The Quantum Physics Of Precognition Or Pseudoscience?

Read the comments too, it has some interesting information.

Whether our brains can use the weird aspects of quantum physics is a side issue, its not important now.

There is a possibility that the future might influence the past, it doesn't mean time flows backwards, nothing flows here. John Wheeler's delayed-choice double-slit thought experiment reveals that an observer today can be partially responsible for generating the reality of the remote past. The past history of the photon is decided now, basing upon how the participator chooses to make a measurement. So there can be a future influence on the past and Roger Penrose has proposed such an idea. But do know that this is still at the speculation stage and not accepted in the mainstream science.

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How does the force such as gravity form?

As said earlier General theory of relativity doesn't see gravity as a force, an object or an apple falls to the ground not due to some attraction force, it falls to the ground due to the curvature of space and time. However the equations of general relativity predicts that there should be particles called as gravitons which carries the gravitational force and many experiments have been conducted in search of this particle but it has not been detected yet but it doesn't mean that it doesn't exist, more powerful experiments are being conducted.

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Is the feeling of laugh and cry only in animals or plants also have feelings?

Its a question which science cannot answer, all science can know is the physiological changes in plants and animals but we cannot know whether they have any real inner feelings in them like we do. To know whether plants have inner feelings or not you have to know what it is like to be a plant which something science cannot provide right now.

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why do we feel unsafe at night but we feel safe at same place in day?

It is because of lack of information to our brains and humans have the ability to imagine things and if you had saw a scary movie in the morning then its likely that you are going to imagine them when things go dark and think that those things may be actually there behind you and obviously get afraid.

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we drink water but what is the element that save us?

There is no single magical potion that saves us, we need all the nutrients or chemicals for our body just as we need water.