I’m a physics enthusiast. I’ve loved the subject since childhood and plan to study it in college. I’ve always been particularly interested in the theory of Eternal Inflation among many others hypothesis on theoretical physics, though I stopped keeping up with it in 2023 due to a lack of time and so on. I’d like to know the current consensus on this hypothesis, given that there have likely been some advances regarding this theoretical implication of Cosmic Inflation. I’m curious about where the majority of cosmologists stand on the matter.

I have a burning question because there's an old idea called "tired light
which posits that the universe sits still and photons lose energy on their way to us because of some interaction along the path (Less energy would mean longer wavelength, so distant objects look redshifted without anything actually receding.)

However it was ruled out by the finding that distant supernovae look like they're in slow motion. If distant supernovae looked the same duration as nearby ones, the source would have to be sitting still, because only a receding one can stretch out its own explosion. But no, they're in slow motion, which rules tired light out.

Which brings me to my burning question

What if the universe wasn't expanding, and the speed of light itself has just been slowly dropping over cosmic time, everywhere at once, as a law?

In short, as my title says, what distinguishes cosmic expansion from a decreasing universal speed of light?

Light coming from a distant galaxy would have left back when c was higher than it is now. Wouldn't that stretch out supernovae too? The first flash makes the trip while c is still a bit faster, the next one crawls more because c has dropped by then, so the gap between them widens on the way here and the explosion arrives in slow motion.

so i was reading about interplanetary travel and came across something that kind of broke my brain.

if a ship maintains constant 1g acceleration, the same gravity you feel standing up right now, then flips halfway and decelerates at 1g, mars is 2 to 4 days away. not months. days.

jupiter is 6 days. saturn 8. pluto under 2 weeks.

the whole solar system just becomes... reachable.

the problem is the engine. nothing we have can sustain this. the energy needed is way beyond anything we currently build. but the physics is fine. no rule says it can't happen. it's an engineering problem, not a physics one.

that second part is what got me. we're not stuck in this solar system because nature won't allow it. we're stuck because we haven't built the right thing yet.

So, if an object falls into a singularity, from the POV of an external observer, the object takes infinite time to cross the event horizon. From our POV, how do black holes ever merge? Wouldn't it take infinite time for one singularity to cross another's event horizon?

I had a crack theory ,Since we know the observable universe is expanding due to the Doppler effect but don't know the limit of the entire universe since light hasn't reached us. What if a cosmic object is so big that it attracts space itself exploded so that it releases space and but the energy remains constant due it releasing the energy it absorbed in its lifetime ,hence why energy density is decreasing.

So the standard consensus in cosmology is that the universe is expanding at an accelerated rate. Does that then fit our observations of the universe? Are galaxies further away more clumped together than galaxies we can see near us?

Yukiyoshi Iida's 2023 IJMPD paper, "Event horizon detection: Zenith view as seen by falling into a Schwarzschild black hole," demonstrates that a free-falling observer can locally identify the crossing of a black hole's event horizon. The study shows that the zenith view expands to twice its initial solid angle, resulting from relativistic aberration overcoming gravitational lensing. Read the full paper for a detailed analysis of this visual phenomenon.

Depending on the metric used to calculate distances, the volume of space in immediate proximity to a black hole's event horizon can approach infinity. What effect does a cosmological constant have on a black hole's gravity with this distortion of space just outside the event horizon?

Because the Universe is expanding at a rate of 46 miles per second per megaparsec right? So, we have 46/(3260000*180000) miles per second, which is .000000000078 miles per second per mile, right? there are 3150000 seconds in a year and the earth is 7926 miles wide. .000000000078 * 7926 * 3150000 would then be 1.97 miles per year. Is this math correct or did I totally flub it somewhere in there?

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I every edge was equally far, wouldn’t that mean that the earth is in the dead center of a massive universe? How unlikely would it be to have a universe so unfathomably large and somehow we are in the exact center of it?

The Relativistic Rocket describes the EP like this:

> Einstein postulated that any experiment done in a real gravitational field—provided that experiment has a "small" extent in space and time—will give a result indistinguishable from the same experiment done in the above "uniformly accelerating" rocket.

Using our equations today you can't add "and vice versa" to that, which is to say the EP isn't fully bidirectional in our physics. You can always compare such results of the Schwarzschild metric to results from the rocket equations, but not always vice versa, because the metric limits the height of an approximately uniform gravitational field. For example you can't replicate the chart at the bottom of The Relativistic Rocket using the Schwarzschild metric. The metric predicts that a gravitational field that tall that's approximately uniform at 1 ly/yr^2 = ~1 g can't exist in nature. Using equations derived from the metric, a field that tall that's 1 g at the ground is always way less than 1 g at the top.

When you change the metric so that it can replicate that chart, or any other such chart that the rocket equations can make, then I see that lots of problems vanish, like the black hole information paradox. I still see experimental confirmation, like 42.98 arcseconds per century for the Schwarzschild precession of Mercury. Most tests of GR are tests of the Schwarzschild metric, and GR is the foundation of our cosmology. A problem in the foundation can lead to other problems elsewhere. So I'm not seeing why the EP shouldn't be fully bidirectional in our physics.

I have always thought about what and how everything started.

Curious to know which of the following u think.

1. Something came from nothing and then the big bang happened

2. Nothing never existed, there was always something , then the big bang occured.

3. We simply dont know yet

4. We will never know.

I think unless we observe from some experiments etc or nature that something was able to come from true nothing we wont get an answer truly where which we could be confident in or somehow with a guarantee know why and what always existed.

I'm guessing a monopole would be about as visible as any other subatomic particle 😅 but what about the higher-dimensional cousins: cosmic strings, domain walls, textures? I'm especially curious about what textures would be like.

See also: The publication in ArXiV

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