Big Bang

[robheus]

 

No you can't talk about time before the big bang. In fact you can even talk about relativistic time during the first instances of the universe since there was no geometry involved ie. All objects in the universe diverged from a single point (without dimensions). So time as we usually see it, cannot be viewed in it geometrical form at the very beginning. This can only happen when geometrogenesis occurs.

 

 

Who says so? The big bang theory does not explicity presuposes that there was no time before the big bang, ie. big bang theory does not equate a model with a singularity at the beginning, many more models are possible.

[Spyman]

My main focus is exactly about "the earliest moments of the Universe's history". The Big bang theory had been established based on "several assumptions". My questions relate directly to those assumptions.

The Big Bang theory is not yet refined to include the earliest moments, your quote is from the "Speculative physics beyond Big Bang theory" chapter, as such the Big Bang theory as it is today does not include any initial condition nor energy source and only describes the evolution from there.

 

There is little evidence regarding the absolute earliest instant of the expansion. Thus, the Big Bang theory cannot and does not provide any explanation for such an initial condition; rather, it describes and explains the general evolution of the universe going forward from that point on.

http://en.wikipedia.org/wiki/Big_Bang

 

 

The Big Bang theory is based on the assumptions that the properties of the Universe are the same everywhere and that our view of it is normal.

 

The Big Bang theory depends on two major assumptions: the universality of physical laws, and the cosmological principle. The cosmological principle states that on large scales the Universe is homogeneous and isotropic.

http://en.wikipedia.org/wiki/Big_Bang#Underlying_assumptions

 

 

If you are shifting the thread to discuss initial conditions then you are talking about the Big Bang itself and not the Big Bang theory.

 

A tale of two big bangs

Whenever you hear or read about cosmology, there is one distinction you should have in the back of your mind - otherwise, matters might get a bit confusing: The term "big bang" has two slightly different meanings, and the answer to questions like "Did the big bang really happen" depends crucially on which of the two big bangs you are talking about.

http://www.einstein-online.info/spotlights/big_bangs

[Aethelwulf]

Who says so? The big bang theory does not explicity presuposes that there was no time before the big bang, ie. big bang theory does not equate a model with a singularity at the beginning, many more models are possible.

 

The Big Bang model does... If you want to talk about time before the Big Bang, you need a new model. Then it wouldn't really be the Big Bang theory, because in the BB theory, space and time began at some point.

 

And yes, the Big Bang theory does equate a singularity at the beginning. Some might see it as a breakdown of the theory, I don't though.

[robheus]

The Big Bang model does... If you want to talk about time before the Big Bang, you need a new model. Then it wouldn't really be the Big Bang theory, because in the BB theory, space and time began at some point.

 

And yes, the Big Bang theory does equate a singularity at the beginning. Some might see it as a breakdown of the theory, I don't though.

 

Incorrect. The big bang theory talks about how the universe develops over long cosmological time frames, and is NOT a theory about how the universe 'began' (there never will or can be a theory about that, since the universe did not begin in the first place).The conventional hot big bang model is in modern cosmology preceded with an inflationary period, a short timeframe in which the universe exponentially fast grew from a very tiny patch of false vacuum and then goes over in a more moderate rate of expansion, after the heat was converted into particles.

Edited July 2, 2012 by robheus

[Aethelwulf]

Incorrect. The big bang theory talks about how the universe develops over long cosmological time frames, and is NOT a theory about how the universe 'began' (there never will or can be a theory about that, since the universe did not begin in the first place).The conventional hot big bang model is in modern cosmology preceded with an inflationary period, a short timeframe in which the universe exponentially fast grew from a very tiny patch of false vacuum and then goes over in a more moderate rate of expansion, after the heat was converted into particles.

 

I disagree. If you ask a cosmologist how the universe began, they will loosely say it began as a singular region of spacetime with infinite curvature - if you ask them how this singularity came about, they will tell you we don't know because nothing in our equations can draw anything accurate from it.

[robheus]

I disagree. If you ask a cosmologist how the universe began, they will loosely say it began as a singular region of spacetime with infinite curvature - if you ask them how this singularity came about, they will tell you we don't know because nothing in our equations can draw anything accurate from it.

 

Which cosmologist did you ask? It is a common fact in cosmology that to explain quite a number of things the big bang theory is unable to explain, inflation cosmology comes to the help. For instance the flatness problem, the horizon problem, the homogeneity of the universe and the monopole problem and fine tuning problem are all solved at the basis of inflationary cosmology. Inflation is the period before the normal big bang jumps in (bario genesis etc.) and is in fact a theory on it's own, assuming inflation basically means that the process (in most models) never ends once started.

 

Edit: The singularity is not part of our past, because simply said the theory of GR breaks down there, and measurements smaller then the planck length/time are physically meaningless.

To argue otherwise is the same as saying that if you clap your hands, based on Newtonian gravity, a singularity would happen because two mass points would be at zero distance away causing the force of gravity to become infinite. Which as we know does not happen, because masses are not realy zero dimensional points and second there is also the electrmagnetic force which causes to masses that are near each other to become repulsed because of the repulsive force of the electron shells. Likewise, a realististic model of the universe has not only to consider gravity, but also quantum mechanics. Quantum mechanics shows that the singularity does not exist, and hence the singularity was not in our past. What DID happen near the fictional singularity is not entirely clear, but the least to say is that our model of this period based on GR alone does not explain it correct enough.

Edited July 2, 2012 by robheus

[Aethelwulf]

Which cosmologist did you ask?

 

I don't need to, I am a physicist. If someone asked me, ''how did the universe come about'', I wouldn't ignore the spacetime singularity, even though I agree every conventional sense of time breaks down. I agreed with this point before.

 

But I still wouldn't ignore the singularity and say the universe existed sometime after. It's the precurser of anything existing. It's a state of infinite energy, space and curvature.

 

 

 

We'll just have to agree to disagree on this I think. It's quite a quibble, because on one hand I agree with you, it does break down, but on the other hand, it's not as if we are led to think it did not exist (just not in any normal physical kind of sense).

Edited July 2, 2012 by Aethelwulf

[David Levy]

Quote: The Big Bang model does... If you want to talk about time before the Big Bang, you need a new model. Then it wouldn't really be the Big Bang theory, because in the BB theory, space and time began at some point.

 

 

 

The most distant galaxy which had been found so far is located 13.1 billion year light away from us.

 

Therefore, there is a possibility that to get for this distance, the time from the big bang is not enough.

 

 

So, in order to use time before the big bang, is there a chance that the big bang theory is not 100% correct???

[J.C.MacSwell]

Quote: The Big Bang model does... If you want to talk about time before the Big Bang, you need a new model. Then it wouldn't really be the Big Bang theory, because in the BB theory, space and time began at some point.

 

 

 

The most distant galaxy which had been found so far is located 13.1 billion year light away from us.

 

Therefore, there is a possibility that to get for this distance, the time from the big bang is not enough.

 

 

So, in order to use time before the big bang, is there a chance that the big bang theory is not 100% correct???

 

The model is incomplete...so there is, obviously, 100% probability that it is not 100% correct.

[Aethelwulf]

Quote: The Big Bang model does... If you want to talk about time before the Big Bang, you need a new model. Then it wouldn't really be the Big Bang theory, because in the BB theory, space and time began at some point.

 

 

 

The most distant galaxy which had been found so far is located 13.1 billion year light away from us.

 

Therefore, there is a possibility that to get for this distance, the time from the big bang is not enough.

 

 

So, in order to use time before the big bang, is there a chance that the big bang theory is not 100% correct???

 

Why is it not enough?

 

Time was probably efficient for gravity to take hold by that time and start forming galaxies... they would have been very volatile but still possible.

 

The model is incomplete...so there is, obviously, 100% probability that it is not 100% correct.

 

100% probability vs 100% probability equals a null result. We obviously have more to our theories than that.

 

I certainly don't believe the BB is perfect... but there is not even such a thing as a 100% probability in science. We deal with probabilities which reach the criteria of experiments and based on that, our BB theory is the theory which fits the bill.

[David Levy]

Quote: Why is it not enough?

 

 

 

In order to get the 13.1 light year distant, the galaxy should travel almost at the speed of light.

 

This is unlogical.

 

Therefore, in order to get to this distant, the time should be much longer than the time from the Big Bang.

 

[Aethelwulf]

Quote: Why is it not enough?

 

 

 

In order to get the 13.1 light year distant, the galaxy should travel almost at the speed of light.

 

This is unlogical.

 

Therefore, in order to get to this distant, the time should be much longer than the time from the Big Bang.

 

 

Well, take into consideration, that momentum transfer is evaluated very early on in the universe, are you saying it is impossible for at least some galaxies to arrange stable galaxies when debris are moving at the same relativistic pace?

 

Take into consideration the inflationary phase. Some parts of the galaxy are still moving at relativistic speeds... (according to Hawking)... and thus he explains these are galaxies, so there is nothing stopping matter forming galaxies relative to us.

[pmb]

Quote: Why is it not enough?

 

 

 

In order to get the 13.1 light year distant, the galaxy should travel almost at the speed of light.

 

This is unlogical.

 

Therefore, in order to get to this distant, the time should be much longer than the time from the Big Bang.

 

You do understand, don't you, that its not that the galaxy is moving through space, its just that there is space being created inbetween gallaxies and that yields an effective increasing distance at a rate which makes the distance between some gallaxies appear faster than the speed of light?

[Aethelwulf]

You do understand, don't you, that its not that the galaxy is moving through space, its just that there is space being created inbetween gallaxies and that yields an effective increasing distance at a rate which makes the distance between some gallaxies appear faster than the speed of light?

 

that as well, if that is what he means??? Who knows...

[Spyman]

Quote: Why is it not enough?

 

 

 

In order to get the 13.1 light year distant, the galaxy should travel almost at the speed of light.

 

This is unlogical.

 

Therefore, in order to get to this distant, the time should be much longer than the time from the Big Bang.

 

Since you mention 13.1 billion lightyears distant I suppose you mean UDFy-38135539 which have a 8.55 redshift.

 

It took 13.1 billion years for light to reach us from UDFy-38135539 but that is not the distance it emitted the light from nor the distance it is located at today. According to current cosmological models space has been expanding between us and galaxies around us while their emitted light have been traveling towards us. As such UDFy-38135539 was approximate 3.17 billion lightyears distant from our current location when it emitted the light we see today and is now around 30 billions lightyears away.

 

Further more while relativity claims that nothing can move through space faster than light there is no limit on how fast space itself can expand and secondly the Universe could very well be larger than it is old so that light from very far objects have not yet had enough time to reach us.

 

While special relativity constrains objects in the universe from moving faster than the speed of light with respect to each other, there is no such theoretical constraint when space itself is expanding. It is thus possible for two very distant objects to be expanding away from each other at a speed greater than the speed of light. Since the parts of the universe cannot be seen after their speed of expansion away from us exceeds the speed of light, the size of the entire universe could be greater than the size of the observable universe.

 

It is also possible for a distance to exceed the speed of light times the age of the universe, which means that light from one part of space generated near the beginning of the Universe might still be arriving at distant locations (hence the cosmic microwave background radiation). These details are a frequent source of confusion among amateurs and even professional physicists. Interpretations of the metric expansion of space are an ongoing subject of debate.

http://en.wikipedia.org/wiki/Metric_expansion_of_space

 

Also please stop fuzzing around with the fonts and sizes, it makes your posts unnecessarily hard to read.

[David Levy]

I'm an Ehgineer.

 

Therefore, I'm quite shoched from the science approch to this issue.

 

If the messured distance is 13.1 Billion years, than IT might be 13.1 billion year.

But, the meaning is that the big bang theory might be is incorrect.

 

Hence, the science comes with new theory as follow: " cosmological models space has been expanding between us and galaxies around us while their emitted light have been traveling towards us"

For me it sounds like science fictions.

 

Why the science try to change the reality if it does not fit the theory???

How come that a measured 13.1 had been changed to 3.17?

In one hand the science claims that all conclutions are based of evidence.

 

But in the other hand, what kind of evidence the science have to support this fiction model???

 

Why they can't take it as is and try to verify if there is someting wrong with the big bang theory???

 

If a doctor measured that you have a fever of 40 c degree. than you a fever.

Now, what would you think if this doctor tells you that based on the last medical module the meaning is 37c???

 

I have found that again and again and again the science comes with new modules to explain someting which is somehow illogical....

 

But always, those modules should support the big bang theory.

 

Don't you think that there is a chance (even a small chance) that what you see is what you see. Hence, the measured result is correct!!!

 

 

 

es

Edited July 3, 2012 by David Levy

[ACG52]

I'm an Ehgineer.

 

Therefore, I'm quite shoched from the science approch to this issue.

 

If the messured distance is 13.1 Billion years, than IT might be 13.1 billion year.

But, the meaning is that the big bang theory might be is incorrect.

 

Hence, the science comes with new theory as follow: " cosmological models space has been expanding between us and galaxies around us while their emitted light have been traveling towards us"

For me it sounds like science fictions.

 

Why the science try to change the reality if it does not fit the theory???

How come that a measured 13.1 had been changed to 3.17?

In one hand the science claims that all conclutions are based of evidence.

 

But in the other hand, what kind of evidence the science have to support this fiction model???

 

Why they can't take it as is and try to verify if there is someting wrong with the big bang theory???

 

If a doctor measured that you have a fever of 40 c degree. than you a fever.

Now, what would you think if this doctor tells you that based on the last medical module the meaning is 37c???

 

I have found that again and again and again the science comes with new modules to explain someting which is somehow illogical....

 

But always, those modules should support the big bang theory.

 

Don't you think that there is a chance (even a small chance) that what you see is what you see. Hence, the measured result is correct!!!

 

 

 

es

 

 

You really seem to know absolutely nothing about cosmology, astronomy, or physics in general. I am quite suspect of your claim to be an electrical engineer. If it's true, it's a condemnation of the science curriculum at whatever institution you attended.

[pmb]

You really seem to know absolutely nothing about cosmology, astronomy, or physics in general. I am quite suspect of your claim to be an electrical engineer. If it's true, it's a condemnation of the science curriculum at whatever institution you attended.

Engineers rarely take more than Physics IO, II and III. Even then they quickly forget most of it. And those courses don't even touch base with astronomy or cosmology.

[Spyman]

I'm an Ehgineer.

 

Therefore, I'm quite shoched from the science approch to this issue.

 

If the messured distance is 13.1 Billion years, than IT might be 13.1 billion year.

But, the meaning is that the big bang theory might be is incorrect.

 

Hence, the science comes with new theory as follow: " cosmological models space has been expanding between us and galaxies around us while their emitted light have been traveling towards us"

For me it sounds like science fictions.

 

Why the science try to change the reality if it does not fit the theory???

How come that a measured 13.1 had been changed to 3.17?

In one hand the science claims that all conclutions are based of evidence.

 

But in the other hand, what kind of evidence the science have to support this fiction model???

 

Why they can't take it as is and try to verify if there is someting wrong with the big bang theory???

 

If a doctor measured that you have a fever of 40 c degree. than you a fever.

Now, what would you think if this doctor tells you that based on the last medical module the meaning is 37c???

 

I have found that again and again and again the science comes with new modules to explain someting which is somehow illogical....

 

But always, those modules should support the big bang theory.

 

Don't you think that there is a chance (even a small chance) that what you see is what you see. Hence, the measured result is correct!!!

 

 

 

es

The distance is NOT measured with a ruler or a measuring tape, we measure the redshift of the light we see and not the actual distance through space.

 

Absorption lines in the optical spectrum of a supercluster of distant galaxies (right), as compared to absorption lines in the optical spectrum of the Sun (left). Arrows indicate redshift. Wavelength increases up towards the red and beyond (frequency decreases).

 

The spectrum of light that comes from a single source (see idealized spectrum illustration top-right) can be measured. To determine the redshift, one searches for features in the spectrum such as absorption lines, emission lines, or other variations in light intensity. If found, these features can be compared with known features in the spectrum of various chemical compounds found in experiments where that compound is located on earth. A very common atomic element in space is hydrogen. The spectrum of originally featureless light shone through hydrogen will show a signature spectrum specific to hydrogen that has features at regular intervals. If restricted to absorption lines it would look similar to the illustration (top right). If the same pattern of intervals is seen in an observed spectrum from a distant source but occurring at shifted wavelengths, it can be identified as hydrogen too. If the same spectral line is identified in both spectra but at different wavelengths then the redshift can be calculated using the table below. Determining the redshift of an object in this way requires a frequency- or wavelength-range. In order to calculate the redshift one has to know the wavelength of the emitted light in the rest frame of the source, in other words, the wavelength that would be measured by an observer located adjacent to and comoving with the source. Since in astronomical applications this measurement cannot be done directly, because that would require travelling to the distant star of interest, the method using spectral lines described here is used instead. Redshifts cannot be calculated by looking at unidentified features whose rest-frame frequency is unknown, or with a spectrum that is featureless or white noise (random fluctuations in a spectrum).

http://en.wikipedia.org/wiki/Redshift

 

 

Our best scientific understanding of cosmological redshift is that space is expanding and the current measurement of a redshift of 8.55 tells us that it was emitted 13.1 billion years ago from a distance of 3.17 billion lightyears and that the now aged source is located around 30 billion lightyears away.

 

Albert Einsteins theory of Relativity is not exactly new, special relativity was published in 1905, and general relativity was published in 1916. It has been tested and confirmed in many various experiments and is now considered a cornerstone of modern physics.

 

 

Don't you think that there is a chance that you can have misunderstandings about modern cosmology that clouds your judgement and jams your logic?

 

Are you prepared to learn and improve your understanding or will you continue to reject given answers as incorrect, science fictions or illogical?

[imatfaal]

!

Moderator Note

ACG52

Please stop attacking the person in your posts and concentrate on criticising the argument or on answering questions raised. Implications of personal dishonesty are to be avoided if at all possible.

You really seem to know absolutely nothing about cosmology, astronomy, or physics in general. I am quite suspect of your claim to be an electrical engineer. If it's true, it's a condemnation of the science curriculum at whatever institution you attended.

[paradigm]

You state that "Our best scientific understanding of cosmological redshift is that space is expanding..." There is a minority of Scientists who would disagree with that statement. They see the cosmic redshift as indicative of the way in which light increases in wavelength as it travels across the Universe. The big bang theory requires that we believe that light doesn't increase in wavelength as it travels across the Universe. Something of an absurdity.

 

paradigm

[too-open-minded]

Most theories are incorrect, all we can do is make them more precise. Although we will never have them completely right, we can only make them better.

 

Unless im mistaken doesnt special relativitey say that a precise measurement is impossible to make?

[imatfaal]

You state that "Our best scientific understanding of cosmological redshift is that space is expanding..." There is a minority of Scientists who would disagree with that statement. They see the cosmic redshift as indicative of the way in which light increases in wavelength as it travels across the Universe. The big bang theory requires that we believe that light doesn't increase in wavelength as it travels across the Universe. Something of an absurdity.

 

paradigm

 

Which part of the "big bang theory requires that we believe that light doesn't increase in wavelength as it travels across the Universe"? Please bear in mind that one of the major predictions of the big bang theory was the CMBR - which is light redshifted from the UV to the microwave by background expansion.

[paradigm]

With the big bang theory, the increasing wavelength of the light from distant galaxies is said to be the result of a Doppler Effect due to the galaxies accelerating away and not a result of light increasing in wavelength as it travels towards us. The CMBR is not left over from the big bang, but is indictative of the fact that there is an emission groundstate to the Universe.

 

paradigm

[imatfaal]

With the big bang theory, the increasing wavelength of the light from distant galaxies is said to be the result of a Doppler Effect due to the galaxies accelerating away and not a result of light increasing in wavelength as it travels towards us. The CMBR is not left over from the big bang, but is indictative of the fact that there is an emission groundstate to the Universe.

 

paradigm

 

That's simply not true. The CMBR is the red-shifted remnant of the hot universe (about 3000k), the universe has expanded and the radiation has been red-shifted to the microwave.

Cosmic background radiation is well explained as radiation left over from an early stage in the development of the universe, and its discovery is considered a landmark test of the Big Bang model of the universe. When the universe was young, before the formation of stars and planets, it was smaller, much hotter, and filled with a uniform glow from its white-hot fog of hydrogen plasma. As the universe expanded, both the plasma and the radiation filling it grew cooler. When the universe cooled enough, protons and electrons could form neutral atoms. These atoms could no longer absorb the thermal radiation, and the universe became transparent instead of being an opaque fog.

http://en.wikipedia....round_radiation

 

The existence of the CMB radiation was first predicted by Ralph Alpher, Robert Herman, and George Gamow in 1948, as part of their work on Big Bang Nucleosynthesis.

http://map.gsfc.nasa..._tests_cmb.html