Quotes About Cosmology

In an unchanging universe a beginning in time is something that has to be imposed by some being outside the universe;

Contanto que o universo tenha tido um início, podemos supor que houve um criador. Mas, se o universo fosse de fato absolutamente contido em si mesmo, sem contorno nem borda, ele não teria início nem fim: ele simplesmente seria. Nesse caso, qual é o papel de um criador?

but also that it is possible that nothing caused the Big Bang. Nothing.

we can really be sure of is that even if the universe is going to recollapse, it won't do so for at least another ten thousand million years, since it has already been expanding for at least that long. This should not unduly worry us: by that time, unless we have colonized beyond the Solar System, mankind will long since have died out, extinguished along with our sun!

For every event in space-time we may construct a light cone (the set of all possible paths of light in space-time emitted at that event), and since the speed of light is the same at every event and in every direction, all the light cones will be identical and will all point in the same direction.

associates and collaborators were Roger Penrose, Robert

associates and collaborators were Roger Penrose

As far as we are concerned, events before the big bang can have no consequences, so they should not form part of a scientific model of the universe. We should therefore cut them out of the model and say that time had a beginning at the big bang.

The laws of physics demand the existence of something called 'negative energy'.

black hole has a boundary called the event horizon. It is where gravity is just strong enough to drag light back and prevent it from escaping.

Banyak orang tak suka gagasan bahwa waktu punya permulaan, barangkali karena terkesan melibatkan campur tangan Ilahi.

What came before the Big Bang? According to the no-boundary proposal, asking what came before the Big Bang is meaningless—like asking what is south of the South Pole—because there is no notion of time available to refer to. The concept of time only exists within our universe.

En consecuencia, si solo sabemos lo que ha sucedido desde el big bang, no podemos determinar lo que sucedió antes. Para nosotros, los sucesos anteriores al big bang no pueden tener consecuencias, de modo que no deberían formar parte de un modelo científico del universo. Por eso deberíamos eliminarlos del modelo y decir que el tiempo tuvo un comienzo en el big bang.

In physics the smallest doll is called the Planck length and is a millimetre divided by a 100,000 billion billion billion.

we shall see, the concept of time has no meaning before the beginning of the universe.

Aristotle, and most of the other Greek philosophers, on the other hand, did not like the idea of a creation because it smacked too much of divine intervention.

One of the big questions we discussed was the origin of the universe, and whether it required a God to create it and set it going.

This means that at earlier times objects would have been closer together. In fact, it seemed that there was a time, about ten or twenty thousand million years ago, when they were all at exactly the same place and when, therefore, the density of the universe was infinite.

We thus have experimental evidence both that space-time can be warped (from the bending of light during eclipses) and that it can be curved in the way necessary to allow time travel (from the Casimir effect).

FIGURE 3.1 Stars

While physics and mathematics may tell us how the universe began, they are not much use in predicting human behavior because there are far too many equations to solve.

Tant que l'Univers débute à une singularité, on peut supposer qu'il a été créé par une entité extérieure. Mais si l'Univers est complètement autonome, sans frontière ni bord, il ne peut être ni créé ni détruit. Il est, tout simplement. Et dans ce cas, quelle serait la place de Dieu ?

If we can accept a single singularity of the Big Bang, on what basis can we reasonably claim no other such singularities are possible?

The First Law of Thermodynamics says that energy and matter cannot be created or destroyed. If this is true, how is it possible that all the energy and matter in our universe were created in the Big Bang?