Time travel to the Past

I used to watch science programs and sci-fi films related with time travel. In those programs they used to describe the time travel as people going into the past or the future using a portal.

Going to the future is possible with Einstein’s theory of Relativity if you are in a rocket that travels near to the speed of light.

But what about travelling back in time? It looks impossible using the basic concepts of Physics.

It is used to say that we can travel through time by Wormholes.

A Wormhole, also known as an Einstein–Rosen bridge, is a hypothetical topological feature of space-time that thought to be a "shortcut" through space-time. It is much like a tunnel with two ends each in separate points in space-time. We don’t know how we are going to travel in the past. But let us assume that we found a way to travel back in time. With a portal like worm hole, if one person can travel through time, then following questions arises in everybody’s mind.

Will there be the past of the man who is travelling?

I watched the Stephen Hawking’s program where he used to say that,

What if I killed myself by travelling back in time?  

But I am not going to ask the same question, but I want to ask questions rather something more related with the basic laws of physics i.e. The Conservation of Energy.

The Conservation of Energy is the fundamental tool we are using all over the Physics. Neither Classical Mechanics nor Quantum Mechanics can work without this Conservation of Energy. Energy can neither be created nor can be destroyed.

If it is assumed that with a time travel portal, if a person could travel through time, then it implies that he is suddenly vanishing from the Universe that we are living.

The human body is simply nothing but the Energy from Einstein’s E = mc^2 equation. That is we are just a form of energy.

If the person vanished through time then it means that Energy is destroyed in that frame of reference.  And if he come suddenly out of the portal by travelling through the past then,

In the reference frame of the Past time that is if somebody is doing experiments in the past and if he just happened to see the person who had been sent from the future, then it implies that in his reference frame Energy is created from nothing. In both of these reference frames Conservation Laws are violated.

May be you can argue that, if I see the Space and time as a unique one that is a reference frame outside the Space and time, then

The Conservation laws are not violated since the Energy disappeared in the Future time is immediately appears in the Past time. So energy is linked and so you will conclude that, “Neither the energy is destroyed nor created”.

But I strongly disagree this argument since from Einstein’s theory of Relativity; Newton’s laws are valid in all reference frames independent of Space and time.

So, Newton’s laws of Motion or Conservation laws should not be violated in both of the reference frames.

Any Energy or any force can’t be created out of nothing. Time travel in backwards that is to the past would violate all of the Conservation Laws.