0
$\begingroup$

I've skimmed articles/blogs and watched videos around this issue, and the universal consensus is that dark matter and dark energy are two different things >> DM is attractive while DE is repulsive.

LOGIC 1: Dark matter is attractive because it resides/surrounds within an individual galaxy's volume space. On the other hand, dark energy is "repulsive" (it pulls galaxies away from each other) because it is outside the volume space of the observable Universe.

Following this logic, as the universe expands, the dark energy that falls into the space volume of individual galaxies will form part of its dark matter and becomes "attractive".

LOGIC 2: If dark energy is really purely repulsive, then it must have started tearing apart visible matter on the outer edges of the Universe.

Logic 1 looks more plausible to me. Following Logic 1, is it possible that a common yet unknown particle is the source of both DM and DE?

$\endgroup$
3
0
$\begingroup$

Not in the sense that you ask. In cosmology, matter is anything whose energy density scales with $a^{-3}$, where $a$ is the scale factor. Dark matter is called dark matter because it is an unknown component of the universe that nonetheless obeys this scaling relation. On the other hand, dark energy does not scale - it is proportional to $a^0$. See the technical definition section of the Wikipedia articles on dark matter and dark energy. Any particle would necessarily be dark matter but not dark energy, because the density of any particle in a box decreases as you increase the size of the box.

However, there are theories that attempt to explain dark matter & dark energy with a single framework. Again, see Wikipedia on dark fluid.

$\endgroup$
0
$\begingroup$

No. Dark matter is mass that can move through spacetime. It scales with the expansion of the universe $a$ as $a^{-3}$. In contrast, dark energy is a property of spacetime itself and scales not at all with the expansion of the universe (which is why it's also called a cosmological constant)

$\endgroup$
1
  • $\begingroup$ "However, there are theories that attempt to explain dark matter & dark energy with a single framework." I do not mean to offend anyone, but I frequently find it confusing when I see the ambiguous word "theory" in the context of scientific discussion. The online Merriam-Webster [ merriam-webster.com/dictionary/theory ] gives nine definitions. It would be very helpful to the reader if the usage included a choice among the various definitions. An alternative method of clarity might be to use the synonym "conjecture" or "speculation" and reserve "theory" to mean the #1 definition. $\endgroup$
    – Buzz
    May 13 '21 at 16:11

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.