Who really found out the Universe's acceleration?

Click For Summary

Discussion Overview

The discussion revolves around the contributions of Edwin Hubble and Brian Schmidt to the understanding of the universe's expansion and acceleration. Participants explore the differences between Hubble's linear relationship of velocity and distance and Schmidt's findings regarding the acceleration of the universe's expansion, examining the implications of these discoveries.

Discussion Character

  • Debate/contested

Main Points Raised

  • Some participants note that Prof. Brian Schmidt's work in 1998 revealed that the universe's expansion rate is increasing, contrasting with Hubble's earlier findings of a linear relationship between velocity and distance.
  • Others clarify that while Hubble established a linear relationship, Schmidt et al. identified a non-linear relationship, suggesting a more complex understanding of cosmic expansion.
  • One participant suggests that Einstein could have been credited with both expansion and accelerated expansion had he taken his original calculations more seriously.
  • Some participants argue that the relationship between distance and velocity is not linear or exponential, indicating a lack of a simple functional form for this relationship.
  • Another viewpoint posits that Hubble's findings imply a uniform expansion of the universe, while Schmidt's work suggests an increasing rate of expansion, likening it to a balloon that expands at an accelerating rate.
  • Participants discuss the concept of newly created space in an accelerating universe containing energy (the cosmological constant), which modifies the rate of expansion, emphasizing its intrinsic non-linearity.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the relationship between distance and velocity in the context of cosmic expansion, with no consensus reached on the specifics of these relationships or the implications of the findings by Hubble and Schmidt.

Contextual Notes

There are unresolved questions regarding the exact nature of the relationship between velocity and distance, as well as the implications of the cosmological constant in the context of an accelerating universe.

Phys12
Messages
351
Reaction score
42
Prof. Brian Schmidt got the Nobel Prize for his work in expansion of the universe which he did in 1998. His team was able to figure out that earlier in the past, the universe's expansion rate was slower than it is right now and it's actually increasing day by day.

However, wasn't the same thing given by Edwin Hubble who said that the velocity of a galaxy is higher if it's farther away. Doesn't it imply that the universe's expansion is accelerating as did Prof. Schmidt's study? What new did Prof. Schmidt and his team really discover?
 
Astronomy news on Phys.org
Please recall that this is not projectile motion under the influence of gravity; rather the expansion of space. The expanding balloon or raisin bread are commonly used analogies.

Hubble found a linear relationship between velocity and distance; Schmidt et al found a non linear relationship between these two variables.
 
  • Like
Likes   Reactions: Phys12
Einstein may have been credited for discovering both expansion and accelerated expansion had he taken his original calculations more seriously.
 
DrSteve said:
Please recall that this is not projectile motion under the influence of gravity; rather the expansion of space. The expanding balloon or raisin bread are commonly used analogies.

Hubble found a linear relationship between velocity and distance; Schmidt et al found a non linear relationship between these two variables.
So, Hubble found that as the distance increased, the velocity increased. So, if you were to plot a graph between distance and velocity, it'll be a straight line. However, Prof. Schmidt's work got an exponential line in the graph, correct?
 
Phys12 said:
So, Hubble found that as the distance increased, the velocity increased. So, if you were to plot a graph between distance and velocity, it'll be a straight line. However, Prof. Schmidt's work got an exponential line in the graph, correct?
The relationship is not linear, but not exponential, either. There is no simple functional form for the general relationship.
 
DrSteve said:
The relationship is not linear, but not exponential, either. There is no simple functional form for the general relationship.
But the basic idea is the same, right? Edwin Hubble got one that said that velocity of galaxies increases as a function of distance, while Brian Schmidt said that the velocity accelerates. So, Edwin Hubble expanded the universe like a balloon at a uniform rate, while Brain Schmidt increased the volume of space added per second to the ballon.
 
Just to be clear, in both cases space is itself expanding (crudely speaking, new space is being created each second), but in the accelerating universe this newly created space itself contains a little energy (the cosmological constant) that in turn modifies how much space is being added each second. So it is intrinsically non-linear.
 
  • Like
Likes   Reactions: Phys12
DrSteve said:
Just to be clear, in both cases space is itself expanding (crudely speaking, new space is being created each second), but in the accelerating universe this newly created space itself contains a little energy (the cosmological constant) that in turn modifies how much space is being added each second. So it is intrinsically non-linear.
All right, thanks! :)
 
  • Like
Likes   Reactions: DrSteve

Similar threads

  • · Replies 6 ·
Replies
6
Views
2K
Replies
18
Views
2K
  • · Replies 8 ·
Replies
8
Views
4K
  • · Replies 6 ·
Replies
6
Views
4K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 49 ·
2
Replies
49
Views
6K
  • · Replies 19 ·
Replies
19
Views
4K
  • · Replies 8 ·
Replies
8
Views
5K
  • · Replies 2 ·
Replies
2
Views
1K