Yes: If Time Machine gets invented then past can be changed but time travel involves a number of problems. For that read Time Travel Paradoxes. But let's be hopeful that it happens in our lifetimes.

I really want to see two things happening in my lifetime. One is the invention of time machine and the other Elixir of life, if that's possible, there must be some aging gene, we gotta locate it and tamper with it for constant renewal of youth and elimination of natural death. We will become immortals then- how cool is that?

What do you mean by these bro...

1. invention of time machine and
2. other Elixir of life,

if you can enlighten with some explanation please ....!!!

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"Success is not final, failure is not fatal: it is the courage to continue that counts" Winston Churchill

No
Past can not be changed because it can not be reached. Infact you will have to come to terms with it, as it is or was. No authority, no cure, all you can do is endure. Future change hoskta he but present or past, nayy.

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And Allah Knows, while you know not. (Al-Quran)

I mean exactly their dictionary definitions

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He that increaseth knowledge increaseth sorrow (Ecclesiastes 1:18)

Could you clarify the term Past.... Past is something which can be found in everything thing but somethings can be changed and some are not

refer a link please..thanks in advance..

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"Success is not final, failure is not fatal: it is the courage to continue that counts" Winston Churchill

Telomeres are already discovered controlling the aging and noble prize had been given for it. There will be no "Elixir of Life"...Only one thing can be done, that's manipulation of telomeres and stem cell therapy. My research is based on this InshAllah soon the review paper is going to be published which will reveal how we can create anything playing with few cells.
Regarding time machine It's impossible. Yes, you may read the passed time more efficiently now...And yes we can have machines which can "see the(not predict) "Future" but the exact time machines which can bring you back physically in the past is an impossible thing...And Nobody is working on it even in the whole world.
"Gya waqt phir hath ata nahin" proverb will remain a truth. Yes, will be able to read the past of a person more accurately in future. e.g How much Calories he has taken, how many relationships he had etc etc...And this will prove the fact that how every thing is being noted by "Karaman Katbeen" is actually stored as a prove in our genes. They will have the hard copy and we have the actual "soft copy" in us...Those who believe it is impossible for God to raise them again is going to be proven wrong soon...Even man will be able to create the exact copy from dead remains of people...
People will see every verse of Quran going to be proven...Every word of Holy Prophet PBUH, will be proven to be right...

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If I am what I have and if I lose what I have, who then am I?

Past chnage karna hei to apne present ho thik kar lo.....

People are working on it, do some research before making such broad claims as no one is working on this in the whole world. And given the fact you've already brought irrelevancies in (particularly a tilt toward making it a conversation on religion) a possible discussion on scientific possibilities, it's futile to have a meaningful conversation with you in this regard.

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He that increaseth knowledge increaseth sorrow (Ecclesiastes 1:18)

Yeah People have worked quite a lot like H.G Wells,Simon Wells,Charles Dickens,George Pal (may be Sean Paul too)...
Sammie have also sung a song on it...
No bringing religion always is not to do any proselytism here...I've reasons but it will again become too religious to grasp for "Liberals"...It's because I never thought that Science and Religion are two different things...If Present day "Mulla bechara of do waqt ki namaz" and Scientist are two different things, it does n't mean we should separate science from religion...Well, that's another lousy debate.
I have told about what are scientific possibilities.
Time travel was first told by religions as well...Like Hinduism,Budhism,Islam..etc..

What's the theory behind??? I will try to describe it in some lay man language...For more detail read Stephen Hawking and Michio Kaku.
You can't "google it" properly even... It's quite difficult to grab well...It took me a lot of years to understand...But still I'm a toddler in this science...One can't be jack of all...



Time is a Physical Quantity just like Distance, Height etc...You can go forward for covering a distance. You can come back as well. Same is true with height...But time is such a quantity in which you can't travel backward.
Time is in "one directional" only in 3-dimensional space...And even in 4th dimension..
To move in space-time matrix you need to move in 4th dimension...And this movement in fourth dimension will cause you to move ahead your present time only if you move with proportions of speed of light...Which is quite impossible..Because for this purpose you have to be with mass to be practically "zero"...Impossible...Yes,It is theoretically possible if we find how to create a beam of light of your frequency i.e if we convert a man's own frequency coherently with a beam of light with same frequency, supposing that each and everything in this world has it's own frequency...
Means practically if a man is converted into radio signal or beam of light only then in that case you can move with such a speed...

Even after that you can move forward in time only...Not backward...Problem solved...Smajh to ap gae hon ge..

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If I am what I have and if I lose what I have, who then am I?