Hubble constant Definition and 71 Threads

I wasn't sure whether or not to post this in the Astronomy section but as this is homework, I decided to post it here. Homework Statement Suppose the Universe was much younger, eg 10,000 yrs old. Find the Hubble constant for such a Universe. Compare with the currently accepted value. What...

Homework Statement I am working on a project for my cosmology course. I need to determine the Hubble constant from time delay in a gravitational lens. We are using QSO 0957+561 for our data. My question is how do I determine the relevant distances Dl, Ds? I have Dls already. The...

Hi everyone, First time posting, sorry if this is in the wrong format or wrong place. For a project in a cosmology course I need to find the Hubble constant from from time delay in a gravitational lens. the one we are using is QSO 0957+561. My question is how to I find the time delay from...

How can you mathematically calculate the Hubble constant at different redshifts? I know it's possible, and I can get the number by using the Cosmos Calculator: http://www.uni.edu/morgans/ajjar/Cosmology/cosmos.html But I want to know the equation they used to calculate the Hubble Constant...

Student here, please forgive... I have a question about relativistic mass in galaxies. Is the mass of far away galaxies affected by expansion of universe? That is: Is mass of a far away galaxy is different for observer there compared to the observer here? Let's say there is a galaxy identical...

Question: As an object approaches C and its length contracts, does space-time contract also, causing the a larger range of the universe to become visible? I.e. if the Hubble space telescope was traveling at high velocity, would it gain access to light from more distant galaxies than it has...

Homework Statement A galaxy is observed to be receding from the Sun with a velocity of 7500 km/s. The distance to the galaxy is determined to be 1.4×10^8 parsecs. From this observation, what is the value of the Hubble Constant (in km/s/Mpc)? Homework Equations The Attempt at a...

Hello! I want to get my data in terms of h70 -1 Sometimes the estimates are in terms of h50 or h70, and I know how to convert those just fine. However, sometimes they give H0 = 100 h Mpc-1 kms-1 instead... My question is, what is this in terms of h? I know that the relation is...

As the universe approaches perfect exponential expansion the Hubble constant approaches a limiting value. What is the limiting value and how long from now will it be reached?

I am reading conflicting interpretation of the Hubble constant in the exponentially expanding accelerating universe. Some say the Hubble constant is continuing to decrease; while others say Hubble constant is now unchanging and has become truly a constant. Which is correct?

Could we set the natural value Hubble constant to be 1 in some calculation of cosmology, like what we do in the natural unit?

Which statement is true? A The apparent speed of recession of a galaxy is given by the product of the Hubble constant and the distance to the galaxy. B The further away a galaxy is, the lower its apparent speed of motion away from us. C A galaxy with a redshift of 5.37 is situated at a...

I wanted to know a bit more about the fact that in the presently accelerating expansion of the universe the Hubble constant is still decreasing. When the universe was decelerating the Hubble constant was decreasing. It is still decreasing in an accelerating universe. Does that mean the Hubble...

The Hubble constant v = Hd tells us recessional velocity of galaxies is proportional to distance. But distance is equivalent to looking back in time. So what we are seeing is the recessional velocities of galaxies at different times in the universe? This surely can't be right, because for an...

It seems to me that in an expanding universe where the expansion rate is accelerating, that the Hubble constant will be greater for near stars than the constant for far stars that were receding at lower rate at the time the light from them was emitted. So when I see a cosmology calculator...

Hi, I am in my second astronomy course and just received a twenty question take home final exam, and I am having trouble with two of the questions. In 2004 astronomers reported finding evidence that certain white dwarfs are 12.1 +- 0.9 billion years old. Assuming an inflationary model in...

The Question One possible value for the Hubble constant is 65Kms Mpc. Calculate in Mpc, the distance from Earth for agalaxy trallening at the speed of light, 3.0\times10^{8} Attempt v=Hd v=3\times10^8 H= 65Km s Mpc First I will convert the constant to ms so that I have both in...

Just got through reading http://www.space.com/scienceastronomy/060807_mm_huble_revise.html" about findings that suggest the Hubble constant is about 15% smaller than previously believed. From the article: The new finding implies that the universe is. . . about 15.8 billion years old and...

Hubble got this forumula , Density=kH^2 k=constant H=Hubble constant What are the experimantal difficulties in determining the density of the universe accurately ? Ans:The mass of the whole universe is difficult to find same to the volume as well...what else ?please help me out...

Bonjour, From what I red (understand??), the Hubble constant is calculated from galaxy's distance (from us and each other). 1) Is the information speed limit (c) considered constant althrough (through out??) the path? 2) Is the distance from us mesured using redshift only? 3) When...

I see often that rhocrit(the critical density of matter), is expressed this way: rhocrit=(3*(H^2))/(8*pi*G) This is not correct because a cosmological constant is missed. This is the Friedmann Equation: H^2=((8*pi*G*rhocrit)/3)+(lambda/3)-(k/(a^2)) Since it is known that the curvature(k)of...