Astronomy & Space Exploration

giggs-beckham said:
Cool I haven't heard of inflation with regards to multiverse theory, I'd be interested to read more so will.
As far as I know the singularity that the universe came from had quantum fluctuations or irregularities so as it expanded or inflated those irregularities remained. This can be detected in the cosmic microwave background which is the earliest light we can see some 380,000years after the big bang.
Areas of this signature are more and less dense and as I believe these denser areas coalesced to form the stars and galaxies.
I'm fascinated by the un observable universe, how far do the stars and galaxies go and if they're infinite then how can the universe be finite in age (13.8 billion years)
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Interesting.
I must admit that I had thought that the tiny fluctuations in the early universe were caused by the violent speed of the cosmic inflation.

But you are probably right.
The term singularity is different from the singularity at the bottom of a black hole.

I understand that we use the term singularity because it is the only thing we know about that is smaller than an electron for example with infinite density and temperature in the trillions.

Anyway. One of the many things I struggle to visualise and understand is a Scalar Field, with its peaks and troughs of energy.
I have read about it but cannot comprehend it in a quantum sense.
You probably understand it far better.
Is there a simple description?
 
Just been playing with google again haha what else are we going to do. So the amount of planck times in a second is 10^43 which is 1 with 43 zeros after it which is I believe 10 tredecillion. This pleases me.
 
inflation tries to explain why our universe is isotropic, homogeneous and has certain observable qualities. Pre-inflation/classic big bang theory assumes that this is down to initial conditions (= doesn't explain why this is/should be the case). Inflation is a mechanism that creates these kind of conditions so one doesn't have to assume that they were initial conditions.
 
Buster15 said:
Interesting.
I must admit that I had thought that the tiny fluctuations in the early universe were caused by the violent speed of the cosmic inflation.

But you are probably right.
The term singularity is different from the singularity at the bottom of a black hole.

I understand that we use the term singularity because it is the only thing we know about that is smaller than an electron for example with infinite density and temperature in the trillions.

Anyway. One of the many things I struggle to visualise and understand is a Scalar Field, with its peaks and troughs of energy.
I have read about it but cannot comprehend it in a quantum sense.
You probably understand it far better.
Is there a simple description?
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I think essentially the singularity at the dawn of the universe is called a white hole which is I believe Stephen Hawking's discovery.
I've heard of the scalar field but dont know what it is.
 
PedroMendez said:
inflation tries to explain why our universe is isotropic, homogeneous and has certain observable qualities. Pre-inflation/classic big bang theory assumes that this is down to initial conditions (= doesn't explain why this is/should be the case). Inflation is a mechanism that creates these kind of conditions so one doesn't have to assume that they were initial conditions.
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Which is first big bang or inflation.
 
giggs-beckham said:
Which is first big bang or inflation.
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its a bit of confusing denomination.
You start with whats called the/a singularity. Thats just a placeholder - a big question-mark. One can extrapolate our best theories back but at some point they break down due to energy/scale and can't be used to describe what happened before that. At the very least, we lack a theory of quantum gravity to go further back.

Thats followed by a very short period of inflation and after inflation ends, classics big bang theory explains how the universe developed, how the first elements formed, how stars formed and so on. There is no "bang" itself in the whole theory; its at best the aftermath of a "bang", which might or might not have happened.

Inflation is a period where the expansion of space happened faster than during the period afterwards (expansion of space still continues) caused by a scalar field, whose energy dissipated.

An example why inflation might be a useful theory:
When we look around we see that space is pretty flat in the grand scheme of things. The math doesn't postulate at any point, that space-time has to be flat. Inflation is a mechanism that would flatten curved space. This avoids postulating flat space as initial condition.
 
PedroMendez said:
its a bit of confusing denomination.
You start with whats called the/a singularity. Thats just a placeholder - a big question-mark. One can extrapolate our best theories back but at some point they break down due to energy/scale and can't be used to describe what happened before that. At the very least, we lack a theory of quantum gravity to go further back.

Thats followed by a very short period of inflation and after inflation ends, classics big bang theory explains how the universe developed, how the first elements formed, how stars formed and so on. There is no "bang" itself in the whole theory; its at best the aftermath of a "bang", which might or might not have happened.

Inflation is a period where the expansion of space happened faster than during the period afterwards (expansion of space still continues) caused by a scalar field, whose energy dissipated.

An example why inflation might be a useful theory:
When we look around we see that space is pretty flat in the grand scheme of things. The math doesn't postulate at any point, that space-time has to be flat. Inflation is a mechanism that would flatten curved space. This avoids postulating flat space as initial condition.
Click to expand...
This is how I see it inflation first then big bang which is still happening everywhere and the universe is isotropic and homogeneous at large scales.
 
giggs-beckham said:
This is how I see it inflation first then big bang which is still happening everywhere and the universe is isotropic and homogeneous at large scales.
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Cosmic inflation is still a theory but one which does answer many of the anomalies associated with the big bang.

And we shouldn't get too hung up on terminology.
You will be very aware that the big bang was nothing of the sort. It is just a term for an event, and probably a catch all. Similar for a singularity.

As to which came first, your understanding of Plank Time shows the incredibly small timeframes.

I use Brian Cox books as a reference because they are so easy to understand.
And I have watched a number of videos by Alan Guth, who lead the cosmic inflation theory.

The consensus seems to believe that a singularity underwent incredibly rapid inflation as a result of energy release from a Scalar Field.

This inflation was much faster than the speed of light, which is permitted because it was space itself inflating, and it lasted for something like 10-29 of a second.
And as it slowed down, it released its energy which became the big bang.

Interesting article on the BBC science website about antimatter.
 
Buster15 said:
Cosmic inflation is still a theory but one which does answer many of the anomalies associated with the big bang.

And we shouldn't get too hung up on terminology.
You will be very aware that the big bang was nothing of the sort. It is just a term for an event, and probably a catch all. Similar for a singularity.

As to which came first, your understanding of Plank Time shows the incredibly small timeframes.

I use Brian Cox books as a reference because they are so easy to understand.
And I have watched a number of videos by Alan Guth, who lead the cosmic inflation theory.

The consensus seems to believe that a singularity underwent incredibly rapid inflation as a result of energy release from a Scalar Field.

This inflation was much faster than the speed of light, which is permitted because it was space itself inflating, and it lasted for something like 10-29 of a second.
And as it slowed down, it released its energy which became the big bang.

Interesting article on the BBC science website about antimatter.
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Well said and in line with how I've interpreted it that documentary I put up is a good summary of the first seconds of creation.
I saw Brian Cox live at a science and comedy show in London it was amazing Chris Hadfield was there also talking about his space walk.
Coxy did a talk on exo planets.
And I'll check out the antimatter article.
 
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Space is water. Black holes are drains. Stars are a result of sonoluminescence.

We all live in a yellow submarine.
 
I've just been looking into the sky for the past hour and saw about 20 moving objects. Was it starlink satellites or meteors from the lyrid meteor shower?
 
predator said:
I've just been looking into the sky for the past hour and saw about 20 moving objects. Was it starlink satellites or meteors from the lyrid meteor shower?
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If they were points of light in a straight line going relatively slowly - Starlink. If they were quick slashes across the sky in various directions - meteors.
 
Ubik said:
If they were points of light in a straight line going relatively slowly - Starlink. If they were quick slashes across the sky in various directions - meteors.
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Thanks. Mustve just been starlink then. Although I did see something one moving in the other direction to all the others which may have been a meteor. It was cool anyway. It fascinates me just looking into the night sky on a clear night. Also while I'm here, do you know what the bright star in the sky tonight was? Venus or North star or other? I'd love to find out more.
 
predator said:
Thanks. Mustve just been starlink then. Although I did see something one moving in the other direction to all the others which may have been a meteor. It was cool anyway. It fascinates me just looking into the night sky on a clear night. Also while I'm here, do you know what the bright star in the sky tonight was? Venus or North star or other? I'd love to find out more.
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Probably Venus! It's obnoxiously bright and around in the evening at the moment.
 
FireballXL5 said:
That Hubble Deep Field image blows my mind every time. It is literally mind boggling.
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In that case, you should check out the Hubble Ultra Deep Field and the Hubble Extreme Deep Field. This is big, and it'd be heresy to put it in a spoiler in this thread. And if anyone is curious, here is where you should look in the sky to see it (if you have the Hubble Space Telescope and a lot of processing power).

690958main_p1237a1.jpg
 
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nimic said:
In that case, you should check out the Hubble Ultra Deep Field and the Hubble Extreme Deep Field.
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And the lensing effects those images show as ive previously described. I dont know how to post photos I'm 10 years off the caff.
 
FireballXL5 said:
That Hubble Deep Field image blows my mind every time. It is literally mind boggling.
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I’ve just started in the astrophotography hobby and the fact that you can image nebulas and galaxies with a 10 year old unmodified DSLR is mind boggling to me. The Hubble stuff does blow your mind. And to think it’s such a small frame of space is even more mind blowing.
 
predator said:
Thanks. Mustve just been starlink then. Although I did see something one moving in the other direction to all the others which may have been a meteor. It was cool anyway. It fascinates me just looking into the night sky on a clear night. Also while I'm here, do you know what the bright star in the sky tonight was? Venus or North star or other? I'd love to find out more.
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Could have been the ISS moving. Look it up here https://spotthestation.nasa.gov/
 
El General 1994 said:
A lot of clever people here :)

Does the Bootes void blow your mind? I find it quite captivating that such a large area has (nearly) nothing there.
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The voids are so amazing to think of imagine being in a solar system like ours in the middle of one of these voids. The night sky would be completely black and not having telescopes. A bit like a fish in a tank not knowing of the world outside.
 
My favourite galaxy is the sombrero galaxy I've got it on canvas. Has anyone else got a favourite or a favourite Hubble image? My other favourite is the horse head nebula in infared.
 
nimic said:
Here's some gravitational lensing.

sdss-j1004-4112-crop.jpg
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George Owen said:
you need to upload the image to a image host first, like this one https://imgbb.com/

then when you get the direct link to your image, post it here.
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Ive tried a few times now with different pics and it says something went wrong etc. I dont remember it being difficult at all to post a pic on redcafe, everyone else seems to find it easy I've got a Samsung s10
 
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