Image Credit: www.wikipedia.org, Albert Einstein.
Was Einstein wrong? Can Einstein ever be proven wrong? If at all yes, then when was it so? Why was he wrong? And how did he go wrong? Are the pertinent questions. This article examines one such rare incidence when Einstein was proven wrong. The article explores the premises or the probable reasons which attributed to a blunder made in history by none other than the legend Albert Einstein.
The scientific misconceptions and social prejudices are so strong at times that they can prove even Albert Einstein wrong. Einstein is considered one of the greatest pioneers in Physics, his theory of general relativity which he proposed in 1915 opened doors to understanding our Universe like never before. One of the most intriguing parts of the ‘Theory of Relativity’ is Einstein’s field equations. Field equations of Einstein basically define gravity as an effect of mass on the fabric of space-time. Now as per the predictions made by him, he speculated that the Universe might either be expanding or contracting taking into account the different forces of nature including the major influencer, the force of gravity.
Reflecting back in history, it is evident that due to the observations and experiments made by the then astronomers, it was claimed that the Universe appeared to be static, eternal, and unchanging. The reason for such observations made could be blamed on the facts, that scientists and astronomers didn’t possess the technology and the level of expertise in observing the Universe as it is today. Thereby, suffering from the inability to observe the different concealed patterns that the Universe was ultimately showcasing. Einstein accepted the results put out by the astronomers and other physicists and hence did revisions to his work based on this criteria.
The Field Equations and the Cosmological Constant:
Einstein was definitely successful in providing the proof that his equations were compatible with how actually the Universe behaves. But when he started working on his Field Equations, he found some obnoxious results, which deferred completely from what prediction Einstein had made earlier regarding the “Acceleration” or “Deceleration” of the Universe. The idea of Einstein’s field equations was to ultimately determine the “effect of gravity” in the entire Universe and to determine whether the Universe was expanding or contracting. Einstein’s field equations are provided for a referral below:
The following equation explains the working of gravity in our Universe in accordance with the fabric of Space-time.
Image Credit: NICOLLE RAGER FULLER, www.sciencenews.org
The equation also suggests the expansion or contraction of our Universe, but as discussed above due to the observations and speculations made by the then astronomers (that the Universe was “static”) this equation stood out to be conceptually “incompatible” with the Universe. According to Einstein, his equation gave him “bizarre” results on incorporating the then considered fact that the Universe is static and unchanging. This resulted in the discovery of a new mathematical quantity called Einstein’s Cosmological Constant (the Greek symbol of Lambda).
Cosmological Constant: Balancing the Universe
The new quantity of Einstein’s Cosmological Constant or simply Cosmological Constant (The greek symbol of lambda), was introduced by Einstein to his field equations to basically stabilize the effect of gravity contracting the Universe. Cosmological Constant was also introduced due to the problem of “managing the density of the Universe”. As per the historically established prevailing scientifically popular knowledge, the density of the Universe should be constant, since it was not expanding or contracting, so the mass will also be constant. This observation was the main factor in altering or reworking on the field equations. Below is the altered Einstein’s field equation with the added “Cosmological Constant” or (Lambda):
Considering the factor of density (greek symbol of Rho), we know that density is equal to mass upon volume (mass/volume) which actually means mass contained in a three-dimensional area or volume is the density. So there were specifically two aspects which had to be thought of by Einstein, they were:
1) The Density of the Universe could be constant (which accounts for the then considered fact that the Universe is static, eternal, and unchanging).
Or,
2) The Density of the Universe should be increasing or decreasing (which accounts for the fact that the Universe might be expanding or contracting).
Image Credit: www.wikipedia.org/astronomy
1) The Universe is expanding with (+ve Acceleration)
2) The Universe is collapsing with Deceleration (-ve Acceleration)
3) The Universe is static and Unchanging
This tells us that the Universe might have either Decreasing Density, Increasing density, or Constant Density of matter in it.
Let’s compare it to a simple example, if someone wants to carry a bag to travel what would the person pick?
1) A Medium-sized bag which is completely full of stuff
Or,
2) A large bag filled with the same stuff, but it is half-filled as compared to the Medium-sized bag.
Yes, the second one right? The larger one. I tricked someone a bit. But if not then you’re intelligent!
You would actually choose the smaller bag putting the reason as, if I have to carry the same amount of material then why would I bother to carry the large bag?
Absolutely correct.
Gravity is like the chooser of the bags and bags are the two stages of Universe (well somehow gravity knows already what would the two stages of Universe look like). Gravity would always choose a Universe in which matter is closer (like the small bag) so that it doesn’t have to put much effort into attracting them to collapse. (Yes gravity in this way is a friend and foe to the Universe).
Actually the Universe was expanding so if you keep shifting your stuff to a larger bag, then again a larger bag and so on, this will imitate an expanding Universe and ultimately the area will be much larger to contain a small amount of stuff, this is the fact that we now know.
But since Einstein had to consider that at those days the, that the Universe was claimed to be static, he had to make the density constant. What Einstein did was pretty amazing but later turned out to him as his “biggest blunder”. He made the Cosmological Constant (Lambda) in his field equation proportional to the density (rho) of the Universe (Lambda~rho), which basically meant that now the Universe could have matter in it and hence would have a density which was actually stable or one can say ‘constant’.
The Expanding Universe:
Alexander Friedmann, a Russian physicist knew that the Universe couldn’t be static, it must be contracting or expanding. Friedmann designed his own equation known as the Friedmann’s Equations to propose the idea regarding the density (rho) and non-static Universe. The special of his equations being the 2nd equation.
The 2nd equation of Friedmann tells us that due to so much matter (hence, mass) in the Universe would definitely result in the force of gravity acting as crunching on the fabric of spacetime, in other, we can say due to all the massive objects (like Galaxies) in our Universe, it would contract or decelerate due to the inward pulling force of gravity. Friedmann derived these equations including the Cosmological Constant (Lambda). He also concluded that unless the Cosmological Constant was real and big enough to overpower inward pulling gravity, the Universe could never expand.
But after it was found out that the Universe wasn’t static but expanding at an ever-increasing rate, Einstein removed the Cosmological Constant (Lambda) from his equation, since it’s simple it wasn’t required anymore. And it turned out that the Cosmological constant did actually overpower Gravity, and hence Physicists call it now as “Dark Energy”.
The “Acceleration” of expansion of the Universe:
After a few years, Edwin Hubble an American Astronomer, discovered that the Universe was not only expanding, it was expanding in an ever-increasing rate. In other words, he found out that the speed of expansion was not constant but increasing. So it will be correct to conclude that the Universe was for sure, accelerating.
Hubble detected this phenomenon by observing the change in the Electromagnetic Spectrum of light and since the Universe was expanding it was stretching the light from a far source even more. This resulted in the light from the source to get “Red-shifted” (simply meaning the light from color blue moved to the color red and then infra-red) hence facilitating the discovery of acceleration of the Universe.
Image Credit: Roen Kelly, astronomy.com, A representation of "Red-shift".
This very simple looking discovery was actually involving very painstaking observations, this was one of the very discoveries which actually proved that whether be it Einstein’s correctness or mistakes the world always benefitted from each of thoughts and to date does to a large extent.
But don’t feel too safe for the idea that our Universe is “the Universe”, it might not be and we might be floating in a bubble bath of other “Universes”, but that’s until next time.
For finding out more info about the above blog kindly visit the following links, which were also used as references:
1) University of Warwick, England. “Warwick.ac.uk”. Version-N/A, Volume – N/A, May 20, 2019.https://warwick.ac.uk/fac/sci/physics/intranet/pendulum/generalrelativity/#:~:text=The%20Einstein%20Field%20Equations%20are, curved%20by%20mass%20and%20energy.&text=%2C%20which%20specifies%20the%20spacetime%20geometry,found%20using%20the%20geodesic%20equation.
2) Friedmann Equation, “Brian Kay- UNCW.edu”, Version- N/A, Date of Publication- N/A, https://uncw.edu/phy/documents/thefriedmannequations.pdf