"काल-अवकाशातील सर्व कण, ऊर्जा आणि पदार्थ यांची गोळाबेरीज" अशी विश्वाची व्याख्या करता येते. आपण पाहू शकत असलेले (दृश्य) विश्व हे संपूर्ण विश्वाचा एक अत्यंत छोटा भाग आहे असे अनेक खगोलशास्त्रज्ञ मानतात.

The universe is all of space and time and their contents. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of energy and matter, and the structures they form, from sub-atomic particles to entire galactic filaments. Space and time, according to the prevailing cosmological theory of the Big Bang, emerged together 13.787±0.020 billion years ago, and the universe has been expanding ever since. Today the universe has expanded into an age and size that is physically only in parts observable as the observable universe, which is approximately 93 billion light-years in diameter at the present day, while the spatial size, if any, of the entire universe is unknown.