A Peek Outside Our Universe

@article{Gaztaaga2022APO,
  title={A Peek Outside Our Universe},
  author={Enrique Gazta{\~n}aga and Pablo Fosalba},
  journal={Symmetry},
  year={2022},
  volume={14},
  pages={285}
}
According to general relativity (GR), a universe with a cosmological constant Λ, like ours, is trapped inside an event horizon, r<3/Λ. What is outside? We show, using Israel (1967) junction conditions, that there could be a different universe outside. Our universe looks like a black hole for an outside observer. Outgoing radial null geodesics cannot escape our universe, but incoming photons can enter and leave an imprint on our CMB sky. We present a picture of such a fossil record from the… 
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References

SHOWING 1-10 OF 25 REFERENCES

The size of our causal Universe

A Universe with finite age also has a finite causal scale. Larger scales can not affect our local measurements or modeling, but far away locations could have different cosmological parameters. The

McVittie's Legacy: Black Holes in an Expanding Universe

We prove that a class of solutions to Einstein's equations---originally discovered by McVittie in 1933---includes regular black holes embedded in Friedmann-Robertson-Walker cosmologies. If the

The Black Hole Universe (BHU) from a FLRW cloud

A FLRW cloud is a solution of classical General Relativity (GR) were a homogeneous fluid of fixed mass M collapses in a free fall, following a radial geodesic R(τ) of the FLRW metric. This solution

The cosmological constant as a zero action boundary

The measured cosmological constant Λ is usually interpreted as Dark Energy (DE) or modified gravity (MG). Here we propose instead that Λ corresponds to a boundary term in the action of classical

The observable universe inside a black hole

A Schwarzschild radial coordinate R is presented for the Friedmann dust‐filled cosmology models. It is shown that a worldline of constant Schwarzschild radial coordinate in the dust‐filled universe

How the Big Bang End Up Inside a Black Hole

The standard model of cosmology assumes that our Universe began 14 Gyrs (billion years) ago with a hot Big Bang expansion out of nothing. It can explain a vast range of different astrophysical data

Inflationary universe: A possible solution to the horizon and flatness problems

The standard model of hot big-bang cosmology requires initial conditions which are problematic in two ways: (1) The early universe is assumed to be highly homogeneous, in spite of the fact that

Cosmological Constraints from Multiple Probes in the Dark Energy Survey.

TLDR
Combined results from these probes derive constraints on the equation of state, w, of dark energy and its energy density in the Universe, demonstrating the potential power of large multiprobe photometric surveys and paving the way for order of magnitude advances in constraints on properties ofdark energy and cosmology over the next decade.

Gravitational Collapse : The Role of General Relativity 1

Stars whose masses are of the same order as that of the sun (M ) can find a final equilibrium state either as a white dwarf or, apparently, (after collapse and ejection of material) as a neutron

The expansion of the Universe is faster than expected

The present rate of the expansion of our Universe, the Hubble constant, can be predicted from the cosmological model using measurements of the early Universe, or more directly measured from the late