Dark Energy Explained: A Layman's Perspective

In summary: The light from that supernova had to travel through expanding space, which caused it to take longer to reach us. In summary, the conversation discusses the origins of the universe, the redshift of light, and the expansion of space. The concept of a singularity being the source of the universe is challenged and it is explained that the entire universe was denser in the past, not just one region. The idea of a Big Bang black hole is refuted, and it is clarified that the speed of light has not been increasing over time. The conversation also addresses the time it takes for light to reach us from distant galaxies and the role of expanding space in this phenomenon.
  • #1
Havanyani
3
0
I am a layman in these matters, but hear me out... The Universe was ejected from the primordial singularity, and that's all the dark energy there was. Light that is coming out of a gravity well is red-shifted. ‘Long ago’ and ‘far away’ mean the same thing. So, the Universe is bounded by its Beginning - by the Singularity that preceded the Big Bang, located 14 billion light years away all around us. Is it not that the red-shift we see in light coming from so-called receding galaxies is rather due to the fact that this light is climbing out of a gravity well (relative to us) at whose bottom lies the Big Bang Singularity beyond? WE are much farther from that bottom than those galaxies are, as they are farther in the past than we are. The light getting to us is more tired after the climb, just as the Cosmic Background Microwave radiation is. The Big Bang black hole still exists just as those galaxies do, out there in the distance, orchestrating cosmic developments through the medium of the speed of gravitational waves, which speed (the speed of light) I suspect has been increasing over time, depending on where you are on the timeline - your distance from the peripheral 'Centre'. I saw reports of a supernova located not much more than 300,000 years after the Big Bang, when the Universe was about a million or so light years across, we are told. It vexes me why it took 13.7 billion years (or so) years for this light to traverse such a small Universe to get to us if the speed of light had not been much lower then. Please someone, critique my reasoning and enlighten me.
 
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  • #2
Why do you think that photons are climbing gravity well? It is true that distant light is coming to us from regions which are (were) much denser, but when that light was emitted exact opposite was true. It was emitted towards regions which are (were) much denser.
Light does not see proper time passing. Photon emitted at, say, t=1000, will be in any point in space during its journey at t=1000.
 
  • #3
Sorry I got sidetracked for such a long time. I have just read your comments of that time. Light climbing out of a near-black hole object must surely be red-shifted. Space is so compressed in there, and light must be traveling slower, but speeding up as it leaves the object. Why should this view not be applicable to the Universe at large? I don't understand what you mean by ancient light having been emitted towards denser regions. Those distant galaxies are in the past when the Universe was denser and their light has just arrived here when the Universer has become less dense.
 
  • #4
Havanyani said:
Sorry I got sidetracked for such a long time. I have just read your comments of that time. Light climbing out of a near-black hole object must surely be red-shifted. Space is so compressed in there, and light must be traveling slower, but speeding up as it leaves the object. Why should this view not be applicable to the Universe at large? I don't understand what you mean by ancient light having been emitted towards denser regions. Those distant galaxies are in the past when the Universe was denser and their light has just arrived here when the Universer has become less dense.

Light is not traveling slower near a black hole. Light ALWAYS travels at c in every frame.

Edit: Also, you seem to think that the big bang happened in one part of the universe and all matter came from there. This is not true. The universe itself was compressed into a tiny tiny volume. The expansion occurs everywhere all at the same time. There was never a dense singularity or region of space that the photon traveled from, to get to a less dense region. The entire universe, in all directions, expanded and became less dense over time.
 
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  • #5
Havanyani said:
I am a layman in these matters, but hear me out... The Universe was ejected from the primordial singularity, and that's all the dark energy there was.

Incorrect. The universe was in no way shape or form "ejected" from a singularity. Spacetime expanded everywhere all at the same time and is still doing so.

Is it not that the red-shift we see in light coming from so-called receding galaxies is rather due to the fact that this light is climbing out of a gravity well (relative to us) at whose bottom lies the Big Bang Singularity beyond? WE are much farther from that bottom than those galaxies are, as they are farther in the past than we are. The light getting to us is more tired after the climb, just as the Cosmic Background Microwave radiation is.

Nope. There is no denser region for the light to come from. When light was emitted from these far away galaxies the entire universe, including the area surround our local area, was denser.

The Big Bang black hole still exists just as those galaxies do, out there in the distance, orchestrating cosmic developments through the medium of the speed of gravitational waves, which speed (the speed of light) I suspect has been increasing over time, depending on where you are on the timeline - your distance from the peripheral 'Centre'.

There is no Big Bang black hole. There is no one location that the universe occupied at the time of the big bang. And I have no idea why you think the speed of light has been increasing over time.

I saw reports of a supernova located not much more than 300,000 years after the Big Bang, when the Universe was about a million or so light years across, we are told. It vexes me why it took 13.7 billion years (or so) years for this light to traverse such a small Universe to get to us if the speed of light had not been much lower then. Please someone, critique my reasoning and enlighten me.

Because the universe is expanding. When the light was emitted we were traveling away from the source. Because we were moving away from the source and because of the expansion of space, the time it has taken for light to reach us has increased from about 1 million years to 14 billion. Had the universe not been expanding and had we been stationary with respect to the emitting galaxy, the light would have reached us in 1 million years.
 

Related to Dark Energy Explained: A Layman's Perspective

1. What is dark energy?

Dark energy is a theoretical form of energy that is thought to make up about 70% of the total energy in the universe. It is believed to be responsible for the accelerating expansion of the universe.

2. How was dark energy discovered?

The existence of dark energy was first inferred in 1998 by astrophysicists studying distant supernovae. They found that the expansion of the universe was accelerating, contrary to what was expected based on the known laws of physics.

3. What is the difference between dark energy and dark matter?

Dark energy and dark matter are often confused, but they are very different. Dark matter is a type of matter that does not interact with light, while dark energy is a type of energy that is thought to be responsible for the expansion of the universe.

4. How does dark energy affect the universe?

Dark energy is thought to be the driving force behind the expansion of the universe. It is believed to be responsible for the observed accelerated expansion of the universe, which means it is counteracting the force of gravity and pushing galaxies further apart.

5. Can dark energy be observed or measured?

At the moment, dark energy cannot be observed or measured directly. Its existence is inferred from the observed effects it has on the expansion of the universe. Scientists are still working to understand more about dark energy and how it can be studied further.

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