As we know at the time of big bang as mentioned by the scientist the universe expanded faster than the speed of light. So does it mean that at that time all the particles present travelled in the time and the age of universe is different from what we know today or scientist have calculated the age keeping the phenomenon in consideration ?
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The Big Bang occurred about 13.7 billion years ago. This number refers to the time experienced by a co-moving observer - that is, an observer who is moving along with the general flow of matter in the universe throughout its history. Since the universe is homogeneous on the large scale, it doesn't make a difference just where you consider this notional observer to be - co-moving observers everywhere would have measured about the same amount of time since the Big Bang. In that sense we can speak of a consistent age of the universe.
The universe did not "expand faster than light". It's true that if you pick two widely separated points, the distance between them is growing at a rate faster than lightspeed. But this expansion happens everywhere at once, uniformly throughout all the space between the two points, and any matter or light in that space just gets carried along with the stretching. The rate of expansion seen between two points is proportional to how far apart the points are to begin with (that's Hubble's law), so it doesn't make sense to say that the whole universe is expanding faster than light - or at any other particular speed.
The right mental image to think about the expansion of the universe is that of stretching a rubber sheet or blowing up a balloon. Imagine drawing dots on the rubber with a marker pen, then stretching it out - the dots get farther apart although each one stays in exactly the same place on the rubber. It's not that the dots are moving, but that the rubber between them is stretching. The dots represent stars or galaxies and the rubber represents space.
Nathan Reed
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