I’m not arguing that we affirmatively live in a virtual universe, just that the assumption of realness made by the scientific community cannot be independently verified.
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Nietzsche described and popularized the “God is Dead” philosophical movement. If you haven’t read the fantastic account of the Madman in the market place, I’ve excerpted it here:

THE MADMAN
Have you not heard of that madman who lit a lantern in the bright morning hours, ran to the market place, and cried incessantly: “I seek God! I seek God!”—As many of those who did not believe in God were standing around just then, he provoked much laughter. Has he got lost? asked one. Did he lose his way like a child? asked another. Or is he hiding? Is he afraid of us? Has he gone on a voyage? emigrated?—Thus they yelled and laughed

The madman jumped into their midst and pierced them with his eyes. “Whither is God?” he cried; “I will tell you. We have killed him—you and I. All of us are his murderers. But how did we do this?
…
Do we hear nothing as yet of the noise of the gravediggers who are burying God? Do we smell nothing as yet of the divine decomposition? Gods, too, decompose. God is dead. God remains dead. And we have killed him.

“How shall we comfort ourselves, the murderers of all murderers?
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There has never been a greater deed; and whoever is born after us—for the sake of this deed he will belong to a higher history than all history hitherto.”

Here the madman fell silent and looked again at his listeners; and they, too, were silent and stared at him in astonishment. At last he threw his lantern on the ground, and it broke into pieces and went out. “I have come too early,” he said then; “my time is not yet. This tremendous event is still on its way, still wandering; it has not yet reached the ears of men. Lightning and thunder require time; the light of the stars requires time; deeds, though done, still require time to be seen and heard. This deed is still more distant from them than most distant stars—and yet they have done it themselves.

Source: Friedrich Nietzsche, The Gay Science (1882, 1887) para. 125; Walter Kaufmann ed. (New York: Vintage, 1974), pp.181-82.]

For history’s sake, let’s review the arguments that “killed God” or rather, destroyed the certainty that He exists:

• His existence cannot be observed or verified (to date) in a scientific fashion.
• Belief in God, then, is superstition.
• We don’t need God to explain the creation of the Universe or of intelligent life. Theories like the Big Bang and Evolution do that for us.
• The Universe is governed my physical laws, with no need of God for governance (e.g. keeping the moon in its orbit).

And why was the Madman mourning his death so dramatically? Because with the death of God comes the loss of any moral authority. We each can have our own opinion about morality, but no scientific reality will help us to prove that one action is definitively more moral than another. Any true atheist can relate to this (sometimes liberating) feeling of being “unmoored”.

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We now find ourselves in an strikingly similar situation. Same stage, same lines, different starring actors. This time instead of God doing the dying, it is the Real Universe lying in the back of the hearse. What a peaceful visage, but so few people marching in the procession?

As a precursor, see once again this discussion on the naturalness of the Universe.

Therein we encounter this doozy:

“Physicists reason that if the universe is unnatural, with extremely unlikely fundamental constants that make life possible, then an enormous number of universes must exist for our improbable case to have been realized. Otherwise, why should we be so lucky? Unnaturalness would give a huge lift to the multiverse hypothesis, which holds that our universe is one bubble in an infinite and inaccessible foam. According to a popular but polarizing framework called string theory, the number of possible types of universes that can bubble up in a multiverse is around 10^500. In a few of them, chance cancellations would produce the strange constants we observe.”

Throughout this discussion, it is always assumed that we live in a real physical universe — just like we used to assume that God existed. Let’s apply the same arguments that killed God to the question of the Real Universe:

• The reality of our Universe cannot be observed or verified (to date) in a scientific fashion.
• Belief in a Real Universe, then, is superstition.
• We don’t need a Real Universe to explain the origin of the Universe or of intelligent life. A Virtual Universe could do that.
• The Universe could be governed by virtual laws (computer code), with no need of space time or reality for governance.

Let’s take the statement: “with extremely unlikely fundamental constants that make life possible, then an enormous number of universes must exist for our improbable case to have been realized.” You only need 10^500 universes if our Universe is real. If the Universe is virtual than it was designed to make life possible. So which is more unlikely, a simulation on the scale of our Universe, or the existence of 10^500 universes? Keep in mind that a million is 10^6.

Even without these discoveries, even if our Universe looked pretty, orderly, and natural, there would still be a non-zero likelihood that it is virtual, especially since virtual universes can have a many-to-one relationship to real universes.

So even though the certainty of a Real Universe is dead — it never existed — we still live in its shadow and the full ramifications of its death could take decades to be realized. Stating this I often meet with blank stares. Perhaps “I have come too early, my time is not yet. This tremendous event is still on its way.”

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And finally, what would it take to prove that our Universe is not virtual? It would not be enough to show that humans cannot create such a simulation in our universe, you would have to prove that there does not exist any universe governed by any set of rules populated by any type of intelligent life that could possibly host our virtual universe.

Proving that makes finding dark energy sound easy.