Expanding space? How is it?

We know, our universe is expanding. Edwin Hubble (et al.) noticed, what was already predicted. The astronomical objects are moving away f...

We know, our universe is expanding. Edwin Hubble (et al.) noticed, what was already predicted. The astronomical objects are moving away from us. The universe is expanding. Farther the object, greater the receding speed. There is an empirical relation between the distance, and the receding velocity, which is called the Hubble constant. What is farther away, the receding speed is faster in linear proportion.

Very likely, that there are objects in our universe that are receding faster than the speed of the light from us. Can we go after them, and reach them? We cannot go faster than the light, or we cannot even go with the speed of the light. However, the answer to this question, can we reach those objects or not, is not so obvious.

The answer to this question depends on how and in what way space is expanding. Is it expanding in a way that the "space units" are expanding, or in a way that more and more space units become existing?

What is called space unit here is the hypothetical building blocks, the smallest volume, the quanta of the space. Do these units actually exist? It is not a defining criterion. They can remain hypothetical, or just an empirical or practical unit of the space. The two cases and the question still remain valid.

The two cases could be described as the existing space becomes bigger and bigger or space becomes more and more. These two possibilities are fundamentally different cases and look like only these two cases can be.

If the space units become larger and larger, we may reach the things that are receding faster than the light. If the space units become more and more, we probably have no chance to reach those objects. The light speed paradox, what was discussed in an earlier thought may vanish.

What method the inflation of the space follows? Can we decide it by observation? We need to consider, what experiment or observation could rule out either one. We should find something that behaves differently in the two scenarios.

We have two types of things, which are moving. These are what we could consider, as they would behave differently in the two cases. One kind of thing has a resting mass, and the other has not. The first is ordinary matter. It can move on any speed if it is less than the speed of the light. The other, which has no resting mass, is the light itself, and some other, not so obvious, not everyday kind of things. This kind of thing can move only with the speed of the light; they cannot stop or slow down.

The light can move differently, lesser speed than its maximum speed if it is going in a matter. In our case, we consider the movement only in empty space. When only space is present, so the movement is in the vacuum, the light is moving with the maximum speed possible and on that speed only.

How would these two types of things behave in the two space-expanding scenarios?

Let us start with the light. Light has a descriptive property; it is its wavelength. It has other features too, but those either relate to the wavelength, or they are constant. How would the wavelength of the light behave in the two space-extending scenarios?

If the space units become bigger and bigger, the wavelength of the light is becomes stretched more and more. The wavelengths of the light grow as space expands. When we see farther and farther, we would see the wavelength of a specific light is becomes longer and longer.

The wavelength of the light is a bit tricky property because different causes can result in the same effect. The wavelength of the light can be stretched at least three different reasons. The three are the Doppler effect, the gravitational red-shift, and the space expansion. All three can contribute to the cause of the wavelength expansion. Scientists agree that the cosmological background radiation, the change of its wavelength is caused by the space expansion, only. The red-shift of the light of the distant astrological objects may be caused by the expanding space AND the Doppler effect as they are actually receding from us, together. We may not need to consider the effect of the gravitational red-shift as a determining cause of the wavelength expansion if we accept the overall flatness of the universe, what the observations show.

An interesting aspect is that the three scenarios can be seen and discussed as a fundamentally same effect: the relative or absolute distortion of the space.

In summary, we can observe the shift of the wavelength, which is definitely caused by the space expansion in the cosmological background radiation and may be partially in the light of the distant astrological objects. According to this observation, the data supports that the space units as space extends become bigger and bigger.

If the space units become more and more, it may have less effect on the wavelength of the light, but because more and more space is available, the actual distance between two objects is become bigger and bigger, so the light needs more time to arrive. We would see, for example in specific cosmological periods, like the necessary time to make a cycle around a cosmological object - defined by the laws of the gravity - becomes longer and longer as we see farther and farther. We would see the time slows down in the distance, and it slows down more and more according to the distance. Alternatively, we could say, the physical laws are changing in the function of the distance. Actually, we cannot see this effect.

Considering the light as the distinctive effect of the two space expanding scenarios, we may state that space extends as the space units become bigger and bigger instead of becoming more and more.

Let us continue with ordinary matter. How would the movement of the matter behave in the two space-expanding scenarios?

As scientists agree, matter holds together by local forces, space expansion, in either case, do not affect the size of the interacting matter.

If the space units are becoming bigger and bigger, and the matter keeps its size, the expansion should create a tension effect. As space - in which the material is - extends, and the matter does not stretch, a holding back effect in the space around the matter could appear. On a small scale, this effect is minuscule. However, the effect accumulates and should be observable in the large scales. The holding back effect can be seen as it would be the presence of an extra matter. It would be seen as undetectable matter, because actually, it does not exist, yet its effect, similar to gravitation, is present. Maybe it is what the scientists describe as the dark matter. It has a real effect on a yet undetected origin.

If the space units become more and more, it may create a stretching effect, also. However, it would create an extra effect too. As the smallest units of the space become more and more, and because by definition, they are the smallest - which means the smallest steps a moving object can take - more and more time would be necessary for the matter to move between two places, as the time forwards. In reality, this effect is small and difficult to measure in small distances, and we have no experience to observe this effect in large distances.

In conclusion, our observations concerning the light and the matter in the different space extending scenarios may suggest that the expansion takes place as the space-units become bigger and bigger, instead of the space-units become more and more. If this speculation describes reality, the statement suggests more conclusions.

Space is stretched and not created.
The main conclusion is that the universe may expand differently as it is usually described. A frequent question, a kind of philosophical is: in what is the universe expanding? The question loses meaning if the expansion of the universe means stretching of the space. No need to expand the universe in something. Everything is present, no occupation of the new area. The universe does not expand into something; it stretches itself.

We may reach, what is faster than light
Because the expansion of the universe does not create new space, the actual distance between two distant objects grows differently than only the actual movement would cause the distancing speed of the objects. As it is usually said about the universe's expansion: the objects are not actually moving; only space becomes bigger between them. If space stretches instead of grows, then when we are moving toward a distant object, space actually will be less between the two objects. If we are patient, and our real, normal, regular speed is faster than the other object, which is receding from us, there will be a finite time when we reach the other object, no matter how far it is. We can overcome space expansion just by moving in space.

Big bang
It is a widely accepted statement, a kind of philosophical also, that the Big bang created the space. Even if the different space expansion methods do not define how everything started, if space expands by stretching instead of creating new, it may lead to a conclusion, that the Big bang is not the moment when the space created. It may already be present at the moment of the Big bang. In this case, the Big bang is the moment when our universe started, and not when the space created.

Inflation
It is a current scientific agreement that shortly after the Big bang, the universe went through an exponential expanding period, it went through inflation. This hypothesis can explain many observations of the universe, like its flatness, the horizontal problem, and its isotropy. If space already present at the Big bang, maybe it no needs to exponentially expand to explain these problems. The inflation, and ultimately the Big bang is a phase change of the already present space. This phase change could create a new kind of state of the space, what we call today to our universe. A phase change can happen instantly, creating a universally same new state with exactly the same parameters. Phase changes are quick processes starting from one state to another new but globally same state. Usually, they result in a different energy level, which could explain the extra energy that appears in the Big bang. Because it results in a globally same state, it could explain the horizon problem and the isotropy. Moreover, because it could start from an original, flat state, it could explain the flatness of the new state, also. If space was always present, no need for inflation, the observations can be explained without inflation. Of course, it would change the whole cosmology and maybe particle theories as well, as we think about them today.

Multiverse
The multiverse concept came from the fact that many of the parameters of our universe have special values creating the universe that we know. If only one parameter would be different and just a little from the many, our universe would be completely another kind, and probably not suitable for life, for our life to exist. That is the tuning problem. How is this possible? The nature-made solution to this problem is that our universe is one of the many other universes, and we are living in the one where we can, where the parameters are suitable. If all the space is always present and the Big bang occupies all of it through a phase change process, how these parallel other universes could exist to provide an explanation of the tuning? The hypothetical solution in the only-one-existing-universe environment for the tuning problem can be the sequential multiverse. In this case, our universe, the only universe is a cyclic type, which has a definite life cycle with the end. The subsequent Big bangs randomly chose between the parameters for the next, new, reborn universe. And we are in the one where we can be.

Expanding space. How is it?