Hubble, therefore, concluded that the redshift phenomenon was an unknown property of space and not a measurement of true space velocity. However, Edwin Hubble's estimates of the expansion implied that the universe was younger than the age of the Earth and the Sun. Hubble noted that light from faraway galaxies appeared to be stretched to longer wavelengths, or reddened, a phenomenon called redshift.īy precisely determining the expansion rate, called the Hubble constant, the cosmic clock can be rewound and the age of the universe calculated. This means that the universe is expanding uniformly in all directions. Using the largest telescope of the time, he discovered that the more distant a galaxy is from us, the faster it appears to be receding into space. In 1929, Edwin Hubble provided the first observational evidence for the universe having a finite age.
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Now, with a lot of perseverance and precise observations, they are approaching one percent accuracy. At first, astronomers were delighted to narrow the expansion estimate to 10 percent accuracy. This value is needed to calculate the age of the universe, estimate its evolution over billions of years, and understand the forces driving it. Four Successful Women Behind the Hubble Space Telescope's Achievementsīefore the Hubble telescope was launched, there was a huge uncertainty over the expansion rate of the universe.Characterizing Planets Around Other Stars.Measuring the Universe's Expansion Rate.Let "Now but over there" mean $\Delta t - \Delta s/c$ in the future of the moment in their frame that the signal bounced off that mirror. Let $\Delta s$ be the distance measured in their frame between their frame and the source of that signal at the moment the signal bounced off the mirror.
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Let $\Delta t$ be however far in the past "a signal from our frame that could have reflected off of a mirror in their frame and come back to us at our present" is in our past. $2$) "Now but over there" is bad physics but I think I can give it a tolerably good definition. Nothing you can see with the naked eye, or even with a moderately powerful telescope, is far enough away that we couldn't send it a signal. $1$) That is: identifiable through mathematical inference from data collected from extremely powerful space telescopes. Most of our observable $^1$ universe will never see any event that is part of our present, nor will we ever see events that would correspond to something like "now but on those very distant objects." $^2$ Those events are not part of our universe. However, we cannot neither see, nor infer from their effects on other parts of the universe, any events that are emitted by something which was, at the time of the event, receding from us at a cosmic expansion rate greater than $c$. We can infer the universe expanding with a speed greater than $c$ based on the redshift of light that has been travelling from a great distance. Note that you would need an extremely powerful telescope to see objects - even whole galaxies - at such at distance. Likewise, the observer on one of the objects with the events can see Earth's distant past, and the still more distant past of the other object. By the time the light from each event reached you, the source of the event was already outside of your universe: what you are seeing is the object's distant past, which is still inside of your universe. Likewise, they will never see you see the other object's event. Cosmic expansion rate between two points is a factor of distance, and two observers with no relative velocity measure the same distance. If two objects with a relative velocity to us of 0 are receding from us because of universe expansion such that the distance between them is increasing faster than $c$, and you see an event on each object that appears simultaneous to you, an observer located with one of those objects at the moment of that object's event will never see the other object's event. I'm not sure of the precise implications to individual statements. It does not appropriately consider the changing rate of expansion of the universe.
![does the universe expand faster than light does the universe expand faster than light](https://www.scienceabc.com/wp-content/uploads/2018/10/nfsl-and-fsl-768x680.jpg)
See the linked article from the comments. Universe expansion is not the same as movement and needs to be treated differently.
Does the universe expand faster than light how to#
See this wikipedia article for how to composite relativistic velocities. Observers with different velocities measure different distances and times such that no relative velocities greater than $c$ are measured. The fact that two objects have a relative velocity to one another greater than $c$ in your frame does not imply that their relative velocity in either of their own frames is greater than $c$.