Is the universe expanding as Newton's frist law states it must?

Question

if my understanding of space is correct, before the universe began space was devoid of matter. in this nothingness matter was formed and began to spread out. if you like the big bang happened causing enough force to overcome gravity. this matter spreading outward would be traveling through empty space. according to Newton's frist law , matter being in motion and traveling in a straight line out into empty space and having nothing to change it's course, no external unbalanced force, would continue expanding ( at least the outer most surface). wouldn't that be in keeping with main stream accepted physics? if not please inform me. thank you, gravity guru.

Answer 1

The theory that describes the expansion of the universe is that of Albert Einstein's General Relativity (1915). According to this theory the universe should be expanding smoothly outwards  over time and possibly slowing down in its expansion rate. In recent years, however, there has come to light evidence to suggest that all is not well with our current view(s) concerning the expansion of the universe. I'll try to explain!

After publishing his General Theory of Relativity in 1915, Einstein explored the consequences of his gravitational field equation.

G = 8πT

In a paper titled 'Kosmologische Betrachtungen zur allgemeinen Relativitatsctheorie' (Cosmological Considerations on the General Theory of Relativity) published in 1917, Einstein found that to model a steady state universe, which was the then favoured model, he had to bastardise his field equation into the parameterised form: -

G(μν) - λg(μν) = -κ(T(μν) - ½g(μν)T)

Where the constant(?) 'λ' is the cosmological constant or a 'fudge factor' that Einstein introduced to make his field equation work for a steady state universe. When Edwin Hubble discovered, in 1925, that the universe was expanding, Einstein commented that this constant was the greatest blunder of his life. It seems that Einstein ignored the implications, implicit, within his field equation that the universe is expanding!

However, a modern interpretation of this constant is that it represents a repulsive aspect to the gravitational force. The repulse force could be viewed as anti-gravity!

Wikipedia, the free encyclopaedia comments, 'In 1998, observations of type Ia supernovae ("one-A") by the Supernova Cosmology Project at the Lawrence Berkeley National Laboratory and the High-z Supernova Search Team suggested that the expansion of the universe is accelerating'. this acceleration is attributed to the presence of 'dark energy'. However, Wikipedia, the free encyclopaedia further comments, 'The simplest explanation for dark energy is that it is simply the "cost of having space": that is, a volume of space has some intrinsic, fundamental energy. This is the cosmological constant, sometimes called Lambda (hence Lambda-CDM model) after the Greek letter λ, the symbol used to mathematically represent this quantity. Since energy and mass are related by E = mc², Einstein's theory of general relativity predicts that it will have a gravitational effect. It is sometimes called a vacuum energy because it is the energy density of empty vacuum.....The cosmological constant has negative pressure equal to its energy density and so causes the expansion of the universe to accelerate.'

I hope this is of some help!

Answer 2

yes it would travel outwards in a straight line. but the problem is that there are other forces acting on the matter that is created. the strong force, electromagnetism, gravity, all of those can change the direction of a particle.

Answer 3

You're mixing up some scientific concepts.

Newton's first law tells us that an object won't change its velocity unless acted upon by an external force.  However, the gravity of a second object IS an external force.  All objects in the universe are acted upon externally due to the gravity of all the other objects.

So, if the expansion of space is ignored, massive objects traveling away from each other will slow down due to their mutual gravitational attraction.

Answer 4

No.

The expansion of the universe has nothing to do with Newton's laws. It is related to general relativity.

The expansion is NOT that things are moving further apart, it is that the DISTANCES between them are increasing because spacetime itself is expanding or relaxing.

At the big bang, spacetime was curled up to an infinitely tiny point. Ever since, as the density of the universe falls, it has effectively been uncurling. What this means is that the size of a metre has been changing over time - in effect.

This is called a metric expansion, and arises as a solution to the Einstein Field Equations.

Answer 5

The expanding universe theory was discovered by the observation of stars and how they scattered light.

The light emitted from stars indicated the bodies were moving away.

In attempt to explain the physics... Like sound, light travels in waves and something similar to the doppler effect ocurrs when the source moves away from the observer. The energy appears to have reduced in frequency and wavelength... (red sunsets).

Gravitational attraction between bodies are also vectors so while bodies are being pull towards each other, they might still be moving towards an initial direction.

Also consider the masses of the bodies and their positions in space.

Answer 6

The expansion of the universe is a hot topic in moder astronomy! So far here are some things to consider:

Was the big bang energetic enough to send everything flying forever and ever? Is everything going to keep getting further and further (cold universe)? Or could everything be gravitationally attracted enough to be pulled back together? This will result in something dubbed the Big Crunch (hot universe). There is also a middle ground where the universe will expand forever but keep slowing down and only turning back at the end of time (still cold universe).

More recently, scientists have detected that not only are galaxies moving away at almost the speed of light at times, they are actually accelerating! There must be some force causing this. That is why scientists believe some 70% of the universe consists of dark energy! It is the best proof of its existence.

So the short answer, is it depends. How much energy was there initially? Enough to fight gravity? What about dark energy?

Answer 7

the big band theory was created because almost every galaxy is a red tint which states that the wavelengths are bigger and that the objects are moving away from us so there must have been an outward moving force to create that... thats the big bang