According to scientists, currently the edge of observable universe from the earth is about 14 billion parsec. This means that the diameter of the universe is nearly 91 billion light years. If we consider all the matter we could see, some say it only makes 4 percent of the matter calculated from the density. What is the universe lacking in such a case. Also which massive things are there which can be observed but not directly seen?

  • $\begingroup$ The missing "mass" is dark matter and dark energy. The "size" of the universe is not a simple concept. One can't take a 91 billion lightyear long ruler, lay it out and get from one end to the other. $\endgroup$ – CuriousOne Feb 1 '16 at 15:42
  • $\begingroup$ @CuriousOne it is dark matter not dark energy.. i think OP is using Newtonian mechanics and so dark energy cannot be included.. $\endgroup$ – Bruce Lee Feb 1 '16 at 15:46
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    $\begingroup$ @BruceLee: The OP is simply quoting numbers he has heard. If one talks about the mass of the universe and the visible mass is 4% (4.9% to be more precise, I believe), then dark energy has to be included. That his mental model is insufficient to make sense of what these numbers mean is OK, we are here to help him with that. $\endgroup$ – CuriousOne Feb 1 '16 at 15:49
  • $\begingroup$ @CuriousOne the imprecision of OP's numbers then saves your day... :P $\endgroup$ – Bruce Lee Feb 1 '16 at 15:52
  • $\begingroup$ @BruceLee: Not at all... if you just take the ratio between matter and dark matter, then it should be more along the 18%. I don't think the OP mistook 4 for 18. $\endgroup$ – CuriousOne Feb 1 '16 at 15:54

The invisible mass in the universe as you mentioned refers to mass which is not visible using electromagnetic radiation. It is called dark matter and was detected by the virtue of its gravitational effects. The diameter of the universe doesn't play much role in your question.

Secondly, there can be many massive things which can't be seen by EM radiation but can be detected otherwise. Precise details are needed to exactly point out such things.

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  • $\begingroup$ thank you all so much . you helped me understand the basics $\endgroup$ – Srinath Pulaverthi Feb 4 '16 at 12:20

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