# Question about the expansion of the universe:

by Nabael
Tags: big bang relativity
 P: 1 Well an interesting idea came across my mind the other day relating to the expansion of the universe, and I have yet to come across an answer to this little pondering through my own insight or digging: (I am sure everyone knows the following statement, but anyway): the theory of relativity states that matter cannot move faster than the speed of light, as the closer you get to it the more energy has to be exerted in order to continue to accelerate that object and too exceed the speed of light, you would need an infinate amount of energy (which not even the universe as a whole contains). The big bang theory states that the universe rapidly expanded from a single point roughly 14.7 billion years ago and has been expanding since. Combining these two points is how my mind came across my current thought: The universe is made of matter and energy, and as such cannot exceed the speed of light. If everything originated from a single point 14.7 billion years ago, logic would dictate that the maximum expansion of the universe cannot exceed a radius of 14.7 billion lightyears in any given direction for a max diameter of roughly 29.4 billion light years. At least from a stand point of matter and light. Yet it is known for a fact that the universe is larger than this, and objects have indeed been found that exceed the diameter of 40 billion light years at its widest point (the recent quasar cluster that also defied the commonly accepted scale of the universe rule). So my question is: How is it that the universe is larger than 14.7 billion light years in radius if it all theoretically started from a single point, and relativity dictates matter cannot move faster than the speed of light?
 P: 1,857 This question gets asked alot. Recent age of the universe places it at 13.78 billion years old. Now light from that period travels to us at the speed of light. However spacetime is expanding. That light having already travelled part of the distance is essentally red shifted. In essence its frequency is stretched. Now spacetime itself can and does stretch faster than the speed of light. Expansion is not limitted by the speed barrier as expansion is not inertia For more detail and better accuracy of the above there is several posts of this nature including tha FAG section. Those posts explain it far better than I just did as Im sure others will point out lol In the cosmology forum there is currently a good explaination with tons of info in the bubble analogy thread. I highly recommend perusing it.
P: 453
 Quote by Nabael Well an interesting idea came across my mind the other day relating to the expansion of the universe, and I have yet to come across an answer to this little pondering through my own insight or digging: (I am sure everyone knows the following statement, but anyway): the theory of relativity states that matter cannot move faster than the speed of light, as the closer you get to it the more energy has to be exerted in order to continue to accelerate that object and too exceed the speed of light, you would need an infinate amount of energy (which not even the universe as a whole contains). The big bang theory states that the universe rapidly expanded from a single point roughly 14.7 billion years ago and has been expanding since. Combining these two points is how my mind came across my current thought: The universe is made of matter and energy, and as such cannot exceed the speed of light. If everything originated from a single point 14.7 billion years ago, logic would dictate that the maximum expansion of the universe cannot exceed a radius of 14.7 billion lightyears in any given direction for a max diameter of roughly 29.4 billion light years. At least from a stand point of matter and light. Yet it is known for a fact that the universe is larger than this, and objects have indeed been found that exceed the diameter of 40 billion light years at its widest point (the recent quasar cluster that also defied the commonly accepted scale of the universe rule). So my question is: How is it that the universe is larger than 14.7 billion light years in radius if it all theoretically started from a single point, and relativity dictates matter cannot move faster than the speed of light?
The big bang doenst state the universe expanded froma single point, rather the bang happened everywhere. The unvierse may be infinite now in which case it was infinite at the bang . The bang simply marks the start of the expansion. As has been pointed out here read the FAq, it will answer your questions.

P: 46
Question about the expansion of the universe:

 Quote by skydivephil The big bang doenst state the universe expanded froma single point, rather the bang happened everywhere. The unvierse may be infinite now in which case it was infinite at the bang . The bang simply marks the start of the expansion. As has been pointed out here read the FAq, it will answer your questions.
I thought it started as a singularity which was an infinitely small point?

EDIT: Ah! I read the FAQ. It seems that is not a popular theory anymore.