Is the “cosmological constant tension” the prime reason that we believe the expansion of the universe is accelerating?Can the cosmological constant change with time?What are the alternative theories of dark energy? ($w neq -1$)Flat universe and accelerating expansionIsn't the accelerating expansion of the universe intuitive?Why is the CMB still visible?Why is CMB not considered as the edge of the universe?Does the cosmological constant represent anti-gravity?Does accelerating cosmological expansion increase beam spread?Are deductions from CMB much less accurate than claimed, owing to approximations in the FLRW model?Could decaying dark energy solve the Hubble tension?
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Is the “cosmological constant tension” the prime reason that we believe the expansion of the universe is accelerating?
Can the cosmological constant change with time?What are the alternative theories of dark energy? ($w neq -1$)Flat universe and accelerating expansionIsn't the accelerating expansion of the universe intuitive?Why is the CMB still visible?Why is CMB not considered as the edge of the universe?Does the cosmological constant represent anti-gravity?Does accelerating cosmological expansion increase beam spread?Are deductions from CMB much less accurate than claimed, owing to approximations in the FLRW model?Could decaying dark energy solve the Hubble tension?
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;
$begingroup$
Background: For a few years now there is significant difference in the calculation of the cosmological constant between standard candles methods and CMB methods. CMB measurement comes from a very young universe (~400k years) and the resulting cosmological constant as calculated by the Planck collaboration is smaller than what is observed today.
Question: Is this so-called "tension" the main reason for talking about accelerated expansion?
I've found a relevant article by Hossenfelder. I understand that according to the article, the answer to this question is "yes; but we've also seen some other minor indications in support of accelerated expansion".
Note: The question is not about whether any of the measurements are plagued by uncertainties or how trustworthy they are in general.
cosmology space-expansion cosmic-microwave-background dark-energy cosmological-constant
asked Jul 26 at 8:24
HelenHelen
6333 silver badges25 bronze badges
$endgroup$
add a comment |
$begingroup$
Background: For a few years now there is significant difference in the calculation of the cosmological constant between standard candles methods and CMB methods. CMB measurement comes from a very young universe (~400k years) and the resulting cosmological constant as calculated by the Planck collaboration is smaller than what is observed today.
Question: Is this so-called "tension" the main reason for talking about accelerated expansion?
I've found a relevant article by Hossenfelder. I understand that according to the article, the answer to this question is "yes; but we've also seen some other minor indications in support of accelerated expansion".
Note: The question is not about whether any of the measurements are plagued by uncertainties or how trustworthy they are in general.
cosmology space-expansion cosmic-microwave-background dark-energy cosmological-constant
asked Jul 26 at 8:24
HelenHelen
6333 silver badges25 bronze badges
$endgroup$
add a comment |
$begingroup$
Background: For a few years now there is significant difference in the calculation of the cosmological constant between standard candles methods and CMB methods. CMB measurement comes from a very young universe (~400k years) and the resulting cosmological constant as calculated by the Planck collaboration is smaller than what is observed today.
Question: Is this so-called "tension" the main reason for talking about accelerated expansion?
I've found a relevant article by Hossenfelder. I understand that according to the article, the answer to this question is "yes; but we've also seen some other minor indications in support of accelerated expansion".
Note: The question is not about whether any of the measurements are plagued by uncertainties or how trustworthy they are in general.
cosmology space-expansion cosmic-microwave-background dark-energy cosmological-constant
asked Jul 26 at 8:24
HelenHelen
6333 silver badges25 bronze badges
$endgroup$
Background: For a few years now there is significant difference in the calculation of the cosmological constant between standard candles methods and CMB methods. CMB measurement comes from a very young universe (~400k years) and the resulting cosmological constant as calculated by the Planck collaboration is smaller than what is observed today.
Question: Is this so-called "tension" the main reason for talking about accelerated expansion?
I've found a relevant article by Hossenfelder. I understand that according to the article, the answer to this question is "yes; but we've also seen some other minor indications in support of accelerated expansion".
Note: The question is not about whether any of the measurements are plagued by uncertainties or how trustworthy they are in general.
cosmology space-expansion cosmic-microwave-background dark-energy cosmological-constant
cosmology space-expansion cosmic-microwave-background dark-energy cosmological-constant
asked Jul 26 at 8:24
HelenHelen
6333 silver badges25 bronze badges
asked Jul 26 at 8:24
HelenHelen
6333 silver badges25 bronze badges
asked Jul 26 at 8:24
HelenHelen
6333 silver badges25 bronze badges
asked Jul 26 at 8:24
HelenHelen
6333 silver badges25 bronze badges
asked Jul 26 at 8:24
HelenHelen
6333 silver badges25 bronze badges
6333 silver badges25 bronze badges
add a comment |
add a comment |
3 Answers
3
active
oldest
votes
$begingroup$
No. Evidence for the accelerating expansion of the universe comes from multiple angles: supernovae data, Baryon acoustic oscillations, the mass functions of galaxy clusters, etc. That the universe's expansion is accelerating is not in doubt; the question is by how much.
answered Jul 26 at 10:36
AllureAllure
3,07511 silver badges30 bronze badges
$endgroup$
add a comment |
$begingroup$
There is a potential tension between low redshift probes of mass clustering and Planck data (CMB measurements). This ongoing speculation might be evidence of new physics or even modifications of general relativity. However, the author of the article you cited seems to have a confusion between the cosmological constant (no tension discussed in the literature) and the Hubble constant (that has $3sigma$ differences), which becomes clear when you read the comments where a noted CMB researcher expresses his views. There is even no real evidence that the cosmological constant is not constant.
So it is really exciting if some tensions in CMB data grows into significant differences. But one should not confuse the cosmological constant with the Hubble constant which are completely different stuffs.
answered Jul 26 at 12:14
RichardRichard
4852 silver badges12 bronze badges
$endgroup$
1
$begingroup$
This answer doesn't address the main confusion on the part of the OP, which was the idea that the recent tension between experimental results was the reason for believing that cosmological expansion has accelerated (which was in fact a result from 2 decades ago).
$endgroup$
– Ben Crowell
Jul 26 at 14:43
1
$begingroup$
I also wondered about Hossenfelder's description of this as a tension in the values of $Lambda$ rather than $H$. It seems unlikely that she just made a silly naive mistake here, since she's a well-known professional in the field. More likely this is a situation where the data analysis doesn't disentangle the two issues.
$endgroup$
– Ben Crowell
Jul 26 at 14:52
$begingroup$
@BenCrowell true and true; I should search Wikipedia first the next time :) As about Λ vs. H I'll try to understand it better and add an edit to the question.
$endgroup$
– Helen
Jul 28 at 17:32
add a comment |
$begingroup$
Cosmologists believe the universe is expanding at an accelerating rate because the measured value of the cosmological is positive.
The "tension" is that the two different methods give different values of the Hubble parameter (from which the cosmological constant can be calculated). There is a low probability ($4.4 sigma$ according to Wikipedia) that these results are due to chance, which leads some people to believe that the cosmological constant is not in fact constant and may vary in space and time. This would be an indicator of new physical effects beyond our current theories. However, all measured values (and data from other sources) still suggest an accelerated expansion.
answered Jul 26 at 10:13
DavidHDavidH
1577 bronze badges
$endgroup$
1
$begingroup$
Cosmologists believe the universe is expanding at an accelerating rate because the measured value of the cosmological is positive. This is tautological. Fitted values of $Lambda$ are simply a measure of the rate of acceleration, the relation being $ddota/a=Lambda/3$ for a vacuum-dominated spacetime. So this is sort of like saying that cosmologists believe $Lambda/3$ to be positive because they measure $Lambda$ to be positive.
$endgroup$
– Ben Crowell
Jul 26 at 14:46
$begingroup$
Thanks for the answer, but it is true that it is only repeating the question in this case...
$endgroup$
– Helen
Jul 28 at 17:24
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
No. Evidence for the accelerating expansion of the universe comes from multiple angles: supernovae data, Baryon acoustic oscillations, the mass functions of galaxy clusters, etc. That the universe's expansion is accelerating is not in doubt; the question is by how much.
answered Jul 26 at 10:36
AllureAllure
3,07511 silver badges30 bronze badges
$endgroup$
add a comment |
$begingroup$
No. Evidence for the accelerating expansion of the universe comes from multiple angles: supernovae data, Baryon acoustic oscillations, the mass functions of galaxy clusters, etc. That the universe's expansion is accelerating is not in doubt; the question is by how much.
answered Jul 26 at 10:36
AllureAllure
3,07511 silver badges30 bronze badges
$endgroup$
add a comment |
$begingroup$
No. Evidence for the accelerating expansion of the universe comes from multiple angles: supernovae data, Baryon acoustic oscillations, the mass functions of galaxy clusters, etc. That the universe's expansion is accelerating is not in doubt; the question is by how much.
answered Jul 26 at 10:36
AllureAllure
3,07511 silver badges30 bronze badges
$endgroup$
No. Evidence for the accelerating expansion of the universe comes from multiple angles: supernovae data, Baryon acoustic oscillations, the mass functions of galaxy clusters, etc. That the universe's expansion is accelerating is not in doubt; the question is by how much.
answered Jul 26 at 10:36
AllureAllure
3,07511 silver badges30 bronze badges
answered Jul 26 at 10:36
AllureAllure
3,07511 silver badges30 bronze badges
answered Jul 26 at 10:36
AllureAllure
3,07511 silver badges30 bronze badges
answered Jul 26 at 10:36
AllureAllure
3,07511 silver badges30 bronze badges
3,07511 silver badges30 bronze badges
add a comment |
add a comment |
$begingroup$
There is a potential tension between low redshift probes of mass clustering and Planck data (CMB measurements). This ongoing speculation might be evidence of new physics or even modifications of general relativity. However, the author of the article you cited seems to have a confusion between the cosmological constant (no tension discussed in the literature) and the Hubble constant (that has $3sigma$ differences), which becomes clear when you read the comments where a noted CMB researcher expresses his views. There is even no real evidence that the cosmological constant is not constant.
So it is really exciting if some tensions in CMB data grows into significant differences. But one should not confuse the cosmological constant with the Hubble constant which are completely different stuffs.
answered Jul 26 at 12:14
RichardRichard
4852 silver badges12 bronze badges
$endgroup$
1
$begingroup$
This answer doesn't address the main confusion on the part of the OP, which was the idea that the recent tension between experimental results was the reason for believing that cosmological expansion has accelerated (which was in fact a result from 2 decades ago).
$endgroup$
– Ben Crowell
Jul 26 at 14:43
1
$begingroup$
I also wondered about Hossenfelder's description of this as a tension in the values of $Lambda$ rather than $H$. It seems unlikely that she just made a silly naive mistake here, since she's a well-known professional in the field. More likely this is a situation where the data analysis doesn't disentangle the two issues.
$endgroup$
– Ben Crowell
Jul 26 at 14:52
$begingroup$
@BenCrowell true and true; I should search Wikipedia first the next time :) As about Λ vs. H I'll try to understand it better and add an edit to the question.
$endgroup$
– Helen
Jul 28 at 17:32
add a comment |
$begingroup$
There is a potential tension between low redshift probes of mass clustering and Planck data (CMB measurements). This ongoing speculation might be evidence of new physics or even modifications of general relativity. However, the author of the article you cited seems to have a confusion between the cosmological constant (no tension discussed in the literature) and the Hubble constant (that has $3sigma$ differences), which becomes clear when you read the comments where a noted CMB researcher expresses his views. There is even no real evidence that the cosmological constant is not constant.
So it is really exciting if some tensions in CMB data grows into significant differences. But one should not confuse the cosmological constant with the Hubble constant which are completely different stuffs.
answered Jul 26 at 12:14
RichardRichard
4852 silver badges12 bronze badges
$endgroup$
1
$begingroup$
This answer doesn't address the main confusion on the part of the OP, which was the idea that the recent tension between experimental results was the reason for believing that cosmological expansion has accelerated (which was in fact a result from 2 decades ago).
$endgroup$
– Ben Crowell
Jul 26 at 14:43
1
$begingroup$
I also wondered about Hossenfelder's description of this as a tension in the values of $Lambda$ rather than $H$. It seems unlikely that she just made a silly naive mistake here, since she's a well-known professional in the field. More likely this is a situation where the data analysis doesn't disentangle the two issues.
$endgroup$
– Ben Crowell
Jul 26 at 14:52
$begingroup$
@BenCrowell true and true; I should search Wikipedia first the next time :) As about Λ vs. H I'll try to understand it better and add an edit to the question.
$endgroup$
– Helen
Jul 28 at 17:32
add a comment |
$begingroup$
There is a potential tension between low redshift probes of mass clustering and Planck data (CMB measurements). This ongoing speculation might be evidence of new physics or even modifications of general relativity. However, the author of the article you cited seems to have a confusion between the cosmological constant (no tension discussed in the literature) and the Hubble constant (that has $3sigma$ differences), which becomes clear when you read the comments where a noted CMB researcher expresses his views. There is even no real evidence that the cosmological constant is not constant.
So it is really exciting if some tensions in CMB data grows into significant differences. But one should not confuse the cosmological constant with the Hubble constant which are completely different stuffs.
answered Jul 26 at 12:14
RichardRichard
4852 silver badges12 bronze badges
$endgroup$
There is a potential tension between low redshift probes of mass clustering and Planck data (CMB measurements). This ongoing speculation might be evidence of new physics or even modifications of general relativity. However, the author of the article you cited seems to have a confusion between the cosmological constant (no tension discussed in the literature) and the Hubble constant (that has $3sigma$ differences), which becomes clear when you read the comments where a noted CMB researcher expresses his views. There is even no real evidence that the cosmological constant is not constant.
So it is really exciting if some tensions in CMB data grows into significant differences. But one should not confuse the cosmological constant with the Hubble constant which are completely different stuffs.
answered Jul 26 at 12:14
RichardRichard
4852 silver badges12 bronze badges
answered Jul 26 at 12:14
RichardRichard
4852 silver badges12 bronze badges
answered Jul 26 at 12:14
RichardRichard
4852 silver badges12 bronze badges
answered Jul 26 at 12:14
RichardRichard
4852 silver badges12 bronze badges
4852 silver badges12 bronze badges
1
$begingroup$
This answer doesn't address the main confusion on the part of the OP, which was the idea that the recent tension between experimental results was the reason for believing that cosmological expansion has accelerated (which was in fact a result from 2 decades ago).
$endgroup$
– Ben Crowell
Jul 26 at 14:43
1
$begingroup$
I also wondered about Hossenfelder's description of this as a tension in the values of $Lambda$ rather than $H$. It seems unlikely that she just made a silly naive mistake here, since she's a well-known professional in the field. More likely this is a situation where the data analysis doesn't disentangle the two issues.
$endgroup$
– Ben Crowell
Jul 26 at 14:52
$begingroup$
@BenCrowell true and true; I should search Wikipedia first the next time :) As about Λ vs. H I'll try to understand it better and add an edit to the question.
$endgroup$
– Helen
Jul 28 at 17:32
add a comment |
1
$begingroup$
This answer doesn't address the main confusion on the part of the OP, which was the idea that the recent tension between experimental results was the reason for believing that cosmological expansion has accelerated (which was in fact a result from 2 decades ago).
$endgroup$
– Ben Crowell
Jul 26 at 14:43
1
$begingroup$
I also wondered about Hossenfelder's description of this as a tension in the values of $Lambda$ rather than $H$. It seems unlikely that she just made a silly naive mistake here, since she's a well-known professional in the field. More likely this is a situation where the data analysis doesn't disentangle the two issues.
$endgroup$
– Ben Crowell
Jul 26 at 14:52
$begingroup$
@BenCrowell true and true; I should search Wikipedia first the next time :) As about Λ vs. H I'll try to understand it better and add an edit to the question.
$endgroup$
– Helen
Jul 28 at 17:32
1
1
$begingroup$
This answer doesn't address the main confusion on the part of the OP, which was the idea that the recent tension between experimental results was the reason for believing that cosmological expansion has accelerated (which was in fact a result from 2 decades ago).
$endgroup$
– Ben Crowell
Jul 26 at 14:43
$begingroup$
This answer doesn't address the main confusion on the part of the OP, which was the idea that the recent tension between experimental results was the reason for believing that cosmological expansion has accelerated (which was in fact a result from 2 decades ago).
$endgroup$
– Ben Crowell
Jul 26 at 14:43
1
1
$begingroup$
I also wondered about Hossenfelder's description of this as a tension in the values of $Lambda$ rather than $H$. It seems unlikely that she just made a silly naive mistake here, since she's a well-known professional in the field. More likely this is a situation where the data analysis doesn't disentangle the two issues.
$endgroup$
– Ben Crowell
Jul 26 at 14:52
$begingroup$
I also wondered about Hossenfelder's description of this as a tension in the values of $Lambda$ rather than $H$. It seems unlikely that she just made a silly naive mistake here, since she's a well-known professional in the field. More likely this is a situation where the data analysis doesn't disentangle the two issues.
$endgroup$
– Ben Crowell
Jul 26 at 14:52
$begingroup$
@BenCrowell true and true; I should search Wikipedia first the next time :) As about Λ vs. H I'll try to understand it better and add an edit to the question.
$endgroup$
– Helen
Jul 28 at 17:32
$begingroup$
@BenCrowell true and true; I should search Wikipedia first the next time :) As about Λ vs. H I'll try to understand it better and add an edit to the question.
$endgroup$
– Helen
Jul 28 at 17:32
add a comment |
$begingroup$
Cosmologists believe the universe is expanding at an accelerating rate because the measured value of the cosmological is positive.
The "tension" is that the two different methods give different values of the Hubble parameter (from which the cosmological constant can be calculated). There is a low probability ($4.4 sigma$ according to Wikipedia) that these results are due to chance, which leads some people to believe that the cosmological constant is not in fact constant and may vary in space and time. This would be an indicator of new physical effects beyond our current theories. However, all measured values (and data from other sources) still suggest an accelerated expansion.
answered Jul 26 at 10:13
DavidHDavidH
1577 bronze badges
$endgroup$
1
$begingroup$
Cosmologists believe the universe is expanding at an accelerating rate because the measured value of the cosmological is positive. This is tautological. Fitted values of $Lambda$ are simply a measure of the rate of acceleration, the relation being $ddota/a=Lambda/3$ for a vacuum-dominated spacetime. So this is sort of like saying that cosmologists believe $Lambda/3$ to be positive because they measure $Lambda$ to be positive.
$endgroup$
– Ben Crowell
Jul 26 at 14:46
$begingroup$
Thanks for the answer, but it is true that it is only repeating the question in this case...
$endgroup$
– Helen
Jul 28 at 17:24
add a comment |
$begingroup$
Cosmologists believe the universe is expanding at an accelerating rate because the measured value of the cosmological is positive.
The "tension" is that the two different methods give different values of the Hubble parameter (from which the cosmological constant can be calculated). There is a low probability ($4.4 sigma$ according to Wikipedia) that these results are due to chance, which leads some people to believe that the cosmological constant is not in fact constant and may vary in space and time. This would be an indicator of new physical effects beyond our current theories. However, all measured values (and data from other sources) still suggest an accelerated expansion.
answered Jul 26 at 10:13
DavidHDavidH
1577 bronze badges
$endgroup$
1
$begingroup$
Cosmologists believe the universe is expanding at an accelerating rate because the measured value of the cosmological is positive. This is tautological. Fitted values of $Lambda$ are simply a measure of the rate of acceleration, the relation being $ddota/a=Lambda/3$ for a vacuum-dominated spacetime. So this is sort of like saying that cosmologists believe $Lambda/3$ to be positive because they measure $Lambda$ to be positive.
$endgroup$
– Ben Crowell
Jul 26 at 14:46
$begingroup$
Thanks for the answer, but it is true that it is only repeating the question in this case...
$endgroup$
– Helen
Jul 28 at 17:24
add a comment |
$begingroup$
Cosmologists believe the universe is expanding at an accelerating rate because the measured value of the cosmological is positive.
The "tension" is that the two different methods give different values of the Hubble parameter (from which the cosmological constant can be calculated). There is a low probability ($4.4 sigma$ according to Wikipedia) that these results are due to chance, which leads some people to believe that the cosmological constant is not in fact constant and may vary in space and time. This would be an indicator of new physical effects beyond our current theories. However, all measured values (and data from other sources) still suggest an accelerated expansion.
answered Jul 26 at 10:13
DavidHDavidH
1577 bronze badges
$endgroup$
Cosmologists believe the universe is expanding at an accelerating rate because the measured value of the cosmological is positive.
The "tension" is that the two different methods give different values of the Hubble parameter (from which the cosmological constant can be calculated). There is a low probability ($4.4 sigma$ according to Wikipedia) that these results are due to chance, which leads some people to believe that the cosmological constant is not in fact constant and may vary in space and time. This would be an indicator of new physical effects beyond our current theories. However, all measured values (and data from other sources) still suggest an accelerated expansion.
answered Jul 26 at 10:13
DavidHDavidH
1577 bronze badges
answered Jul 26 at 10:13
DavidHDavidH
1577 bronze badges
answered Jul 26 at 10:13
DavidHDavidH
1577 bronze badges
answered Jul 26 at 10:13
DavidHDavidH
1577 bronze badges
1577 bronze badges
1
$begingroup$
Cosmologists believe the universe is expanding at an accelerating rate because the measured value of the cosmological is positive. This is tautological. Fitted values of $Lambda$ are simply a measure of the rate of acceleration, the relation being $ddota/a=Lambda/3$ for a vacuum-dominated spacetime. So this is sort of like saying that cosmologists believe $Lambda/3$ to be positive because they measure $Lambda$ to be positive.
$endgroup$
– Ben Crowell
Jul 26 at 14:46
$begingroup$
Thanks for the answer, but it is true that it is only repeating the question in this case...
$endgroup$
– Helen
Jul 28 at 17:24
add a comment |
1
$begingroup$
Cosmologists believe the universe is expanding at an accelerating rate because the measured value of the cosmological is positive. This is tautological. Fitted values of $Lambda$ are simply a measure of the rate of acceleration, the relation being $ddota/a=Lambda/3$ for a vacuum-dominated spacetime. So this is sort of like saying that cosmologists believe $Lambda/3$ to be positive because they measure $Lambda$ to be positive.
$endgroup$
– Ben Crowell
Jul 26 at 14:46
$begingroup$
Thanks for the answer, but it is true that it is only repeating the question in this case...
$endgroup$
– Helen
Jul 28 at 17:24
1
1
$begingroup$
Cosmologists believe the universe is expanding at an accelerating rate because the measured value of the cosmological is positive. This is tautological. Fitted values of $Lambda$ are simply a measure of the rate of acceleration, the relation being $ddota/a=Lambda/3$ for a vacuum-dominated spacetime. So this is sort of like saying that cosmologists believe $Lambda/3$ to be positive because they measure $Lambda$ to be positive.
$endgroup$
– Ben Crowell
Jul 26 at 14:46
$begingroup$
Cosmologists believe the universe is expanding at an accelerating rate because the measured value of the cosmological is positive. This is tautological. Fitted values of $Lambda$ are simply a measure of the rate of acceleration, the relation being $ddota/a=Lambda/3$ for a vacuum-dominated spacetime. So this is sort of like saying that cosmologists believe $Lambda/3$ to be positive because they measure $Lambda$ to be positive.
$endgroup$
– Ben Crowell
Jul 26 at 14:46
$begingroup$
Thanks for the answer, but it is true that it is only repeating the question in this case...
$endgroup$
– Helen
Jul 28 at 17:24
$begingroup$
Thanks for the answer, but it is true that it is only repeating the question in this case...
$endgroup$
– Helen
Jul 28 at 17:24
add a comment |
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StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
