# Question(s) about inflation and other.

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Heya all, im new in the scene( the stargazing and this)

I have watched many docus like

-Through the wormhole with morgan freeman

-Many bbc horizons (To infinity and beyoned, who is afraid of a big black hole, is everything we know about the universe wrong, etc etc)

-Stephan hawking (the 3 part on aliens/time travel and the theory of everything)

wel and some i cannot even remember

-- current theory says right after the big bang inflation took over

-quote from wiki: inflation is the theorized extremely rapid exponantial expension of the early universe by a factor of at least 1078 in volume, driven by a negative-pressure vacuum energy density, It lasted from 10−36 seconds after the Big Bang to sometime between 10−33 and 10−32 seconds. Following the inflationary period, the universe continues to expand.

-- In my mind it is actually saying that there is a greater speed then the speed of light ( inflation itself went way faster then the speed of light?)

- i mean the universe i 13.7 billion years old?, so it would be max 27.4 billion light years?,

( they say there hubble saw galaxies @ 46 billion lightyears from us in both directions so 92 from one another)

then they say, because of inflation:P, the complete universe is to the observable universe, as the observable universe is to an atom ( 10^24 times bigger or so)

does this mean that when the observable universe is 96 billion light years across, and the actual universe is 9.6e+10*10^24 = 9.6e+34

when speed of light is the limit it's max 27.4e+10 across, so

9.6e+32/27.4e+10= approx: 3.5e+23, so the expension went

350364963500000000000000 times faster then the speed of light???

is it that the expension of the universe is so weird it doesn't have to make sense that it breaks the speed limit?, or am i just completely wrong here...,

btw in bbc horizon to infinity and beyond, they say the universe is infinitely big because of inflation, and that everything happens all the time(as long as there is a chance of it happening), because you can ''try'' infinite times, so there are infinitely earths our there and copies of you and me, even with the exact same lives/momories/thoughts, ,so me asking this question with excactly these words means there is a chance of it, and it will happen infinite amount of times:P?, and maybe in some i will ask different questions or not add this part to it...., maybe have less typos ,who knows

makes me feel better about myself knowing infinite other versions of me out there being dumber/uglier , and also the oppisite offcourse, am i excactly in the middle then ?:)

greetz a 22y old boy with infinitely many questions in his mind:D

also a totally different question, do scientists make simulation about what we are observing looks like at this time?, i mean when you watch the andromeda galaxy your looking as it was 2.5 million years ago, do they simulate how things look right now there( is this even possible on such a scale), even when observing the center of our own galaxy means looking like it was around 26000 years ago, the further you look the harder it is to simulate correctly i guess?, just wondering if anyone knows if this is being done .

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IIUC: The speed of light is only the limiting speed WITHIN the universe (because of the limitations of the laws of physics within our universe). The expansion of the universe into ... whatever ... is not limited by SoL.

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also a totally different question, do scientists make simulation about what we are observing looks like at this time?, i mean when you watch the andromeda galaxy your looking as it was 2.5 million years ago, do they simulate how things look right now there( is this even possible on such a scale), even when observing the center of our own galaxy means looking like it was around 26000 years ago, the further you look the harder it is to simulate correctly i guess?, just wondering if anyone knows if this is being done .
Well they have simulated the evolution of the Universe from its earliest times to the present day

e.g.

Millennium Run - Wikipedia, the free encyclopedia

However, simulating individual galaxies is tricky, as even the largest computers cannot handle enough particles.

On the whole, most folks don't bother simulating the future, as you need to compare with real observations, and you can only ever see the past. However, there are some simulations out there of what might happen when M31 and the Milky Way collide.

NigelM

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-- In my mind it is actually saying that there is a greater speed then the speed of light

Actually, the speed of light is greater than the speed of light!

In flat spacetime, and using a particular definition of distance, the speed of light is

c = 300,000 kilometres per second.

Now consider the expanding universe. Suppose someone in galaxy A fires a laser pulse in a direction directly way from our galaxy. According to us, and using the standard definition of cosmological speed, the speed of the laser pulse is

c + galaxy A's recession speed.

So, in my first sentence, the first "speed of light" refers to the cosmological speed of light, while the second "speed of light" refers to c = 300,000 kilometres per second. Even during inflation, the speed of expansion is always strictly less than the cosmological speed of light.

The speed c + galaxy A's recession speed seems intuitive, but sometimes human intuition is remarkably unreliable, and this expression can also be derived by the running through the maths of cosmological models.

Edited by George Jones
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also a totally different question, do scientists make simulation about what we are observing looks like at this time?, i mean when you watch the andromeda galaxy your looking as it was 2.5 million years ago, do they simulate how things look right now there( is this even possible on such a scale), even when observing the center of our own galaxy means looking like it was around 26000 years ago, the further you look the harder it is to simulate correctly i guess?, just wondering if anyone knows if this is being done .

There's not really any point in doing it. Each individual galaxy is different and ever changing, so thinking what Andromeda is looking like "now" doesn't really tell you anything that interesting. There is nothing special about "now" (as defined by time on the Earth), so it's much more interesting to try and work out *how* things change and evolve in the universe, rather than knowing what they are doing at a specific arbitrary point in time.

Another way of putting it is to consider that 2.5 million years on a cosmic timescale is the equivalent of about one day of your life. I don't imagine I'd learn much more about you if I took a picture of you today and tried to work out what you'd look like tomorrow... If however, I could get a look at your photo albums since you were born -- that would give me a pretty good idea of how you (and by extension other humans) grow up and change over time. That's basically what we do when we look further back in time (by looking further away), and hence try to piece together how galaxies evolve and grow up in the "adult" galaxies we see around us today.

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ok, that clears things up a bit

and what about the infinite universe?

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You can have an infinite universe without copies of yourself/the earth in it.

Think of the positive integers: 1, 2, 3, 4, 5...

That's an infinite series, but it doesn't contain PI, any other fractions, negative numbers, etc.

Andy

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and what about the infinite universe?

Completely untestable. Little more than metaphysics...

other may disagree

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Perhaps the word "unbounded" is better than infinite?

Andy

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However, simulating individual galaxies is tricky, as even the largest computers cannot handle enough particles.

Hence Milkyway@Home?

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The expansion of the universe into ... whatever ... is not limited by SoL.

The universe is probably infinite (and probably always was), you should think of expansion as the separation of large structures increasing within the universe.

Edited by palebluedot

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