What temperature is space?

[J.C.MacSwell]

I wonder if the nightsky darkness had anything to do with dooming steady state

 

Not the Hoyle Model. A Horizon would be maintained by the "Hubble flow" (and in this case the Hubble constant really was "constant")

[Martin]

Not the Hoyle Model. A Horizon would be maintained by the "Hubble flow" (and in this case the Hubble constant really was "constant")

 

I see! Interesting to look at these old models.

since the Hubble parameter was constant, the Hubble radius could not go roaring out into space the way it has been doing

so light from any galaxy receding at speed c or better would never reach us. the Hubble radius was constant and therefore acted as a bound on the observable universe. So in that steadystate model the night sky could be dark!

 

fascinating. and then our own hubble volume of space would tend to get emptier and emptier, so hoyle had to postulate something that kept replenishing it, the constant creation of atoms out there in the void.

 

I guess the "steady state" school of cosmologists are getting pretty old now. I saw a news item about the passing of one of the founders of that model, just last week I think.

[Skye]

Considering that there's very little in space, and so there's minimal heat exchange, would it then feel nice and warm (body temp.)?

[Martin]

Considering that there's very little in space, and so there's minimal heat exchange, would it then feel nice and warm (body temp.)?

 

I believe that in the shade the problem would be dumping waste heat from your body. but maybe it is not too bad.

maybe you need to vent expendable gas to carry off heat,

or you need something like a heatpump and a radiator surface to radiate it away. or an even larger radiator surface with no heat pump

 

I am just guessing

 

If you were not in the shade the problem would be much worse because of sunlight

 

maybe someone familiar with manned space program engineering knows definitely?

[swansont]

Considering that there's very little in space, and so there's minimal heat exchange, would it then feel nice and warm (body temp.)?

 

There's radiation heat transfer. Since you're radiating to a 2.7 K background, and it's the only game in town, it's significant. Radiation goes as T⁴. You would eventually get cold.

[J.C.MacSwell]

There's radiation heat transfer. Since you're radiating to a 2.7 K background, and it's the only game in town, it's significant. Radiation goes as T^{4[/sup']. You would eventually get cold.}

 

^{Inspite of virtually no conduction or convection losses you would freeze your butt in a hurry without adequate protection/spacesuit, would you not?}

[swansont]

Inspite of virtually no conduction or convection losses you would freeze your butt in a hurry without adequate protection/spacesuit, would you not?

 

If I took your question excruciatingly literally, using the equation here, I find that a 90 kg perfect radiatior with a surface area of a square meter would reach freezing in ~1.5 hours, and that ignores the fact that we generate about 100 Watts. A 37 C body with those properties radiates about 525 Watts. Since that is long compared to the time you can hold your breath, I wouldn't worry about literally freezing your butt.

 

You'd certainly feel extremely chilly, though - we are much more sensitive to heat transfer than we are to temperature. That's why a good heat conductor like metal feels colder than an insulator, like wood, even if they are at the same temperature.

[Johnny5]

according to what law of gravity would the pieces of shrapnel slow down?

if newtonian gravity' date=' it is not accurate

[/quote']

 

Let us start out using Newton's formula as a first approximation at least.

 

[math] \vec F = G \frac {M1M2}{R^2} [/math]

 

Now what is wrong with this?

 

I expect you to say something about R(t).

[Johnny5]

maybe someone familiar with manned space program engineering knows definitely?

 

That is the kind of person I need to speak to. I have some simple questions that someone with that kind of expertise could answer. And NASA should come out with some videos of experiments done in space, for those of us not fortunate enough to go into space.

[J.C.MacSwell]

I see! Interesting to look at these old models.

since the Hubble parameter was constant' date=' the Hubble radius could not go roaring out into space the way it has been doing

so light from any galaxy receding at speed c or better would never reach us. the Hubble radius was constant and therefore acted as a bound on the observable universe. So in that steadystate model the night sky could be dark!

 

fascinating. and then our own hubble volume of space would tend to get emptier and emptier, so hoyle had to postulate something that kept replenishing it, the constant creation of atoms out there in the void.

 

I guess the "steady state" school of cosmologists are getting pretty old now. I saw a news item about the passing of one of the founders of that model, just last week I think.[/quote']

 

So what background temperature would the Hoyle Model be?

I don't know if Hoyle looked at it, although he was pretty thorough in a lot of his work which contributed to the big bang models also, even though he didn't believe in them.

 

Edit: OK, I just read (in "Companion to the Cosmos" by John Gribbin) that Hoyle didn't think that his creation field model would have a background radiation. Anyone have an idea why not? I can't picture that. It seems to me that this model puts a limit on "Olber", not snuff him out.