Observations suggest that the intergalactic gas in our universe is a little hotter than it should be. Recently, a team of astrophysicists have used sophisticated computer simulations to propose a radical solution: an exotic form of dark matter known as “dark photons” could be heating the place up.
These strange particles would be the carriers of a new, fifth force of nature that normal matter does not experience, but occasionally these dark photons can flip their identities to become regular photons, providing a source of heat.Feeling neutral
We could find such dark photons by observing the intergalactic gas using what’s known as the Lyman-alpha forest. When we observe light from a distant, bright object, like a quasar (glowing objects powered by black holes at the centers of distant galaxies), there is a series of gaps in an otherwise smooth spectrum of light from that faraway object.
Here’s why: that light has to filter through billions of light-years of gas to reach us. Occasionally that light will pass through a relatively dense clump of neutral hydrogen — a type of hydrogen that consists of one proton and one neutron, and which permeates gas clouds throughout the universe.
Most of that light will pass through unaffected, but a very specific wavelength of light will get absorbed. This wavelength corresponds to the energy difference needed to bump an electron from its first to its second energy level inside the hydrogen atoms.
When astronomers look at the light coming from that object, it will look otherwise unremarkable except for a gap at the wavelength of that specific energy transition, known as the Lyman-alpha line.
The light from the distant object will pass through multiple clouds and clumps of neutral hydrogen. The expansion of the universe causes the gaps to redshift to different wavelengths, with a new gap appearing at a different wavelength depending on the distance to the particular gas clouds.. The end result of this is the “forest”: a series of lines and gaps in the spectrum. Getting hot in here
These Lyman-alpha gaps can also be used to measure the temperature of each gas cloud. If the neutral hydrogen were perfectly still, the gap would appear as an incredibly thin line. But if the individual molecules are moving, then the gap will widen because of the kinetic energy of those molecules. The hotter the gas, the more kinetic energy the molecules have, and the wider the gap.
In a paper appearing in November in the journal Physical Review Letters, a team of astrophysicists have pointed out that by using this method, it seems that the clouds of gas that scatter between galaxies are a little too hot. Computer simulations of the evolution of those gas clouds predict them to be just a little bit colder than we observe, and so perhaps something is heating up those clouds that isn’t currently accounted for in our astrophysical simulations.
One possible explanation for this discrepancy is the presence of “dark photons” in our universe, the study authors claim. This is a very hypothetical form of dark matter, the mysterious, invisible substance that accounts for roughly 80% of all the mass in the universe, yet doesn’t seem to interact with light.
Since astronomers do not currently understand the identity of dark matter, the field is wide open with possibilities as to what it could be. In this model, instead of the dark matter being made of invisible particles (like a phantom version of electrons, for example), it would instead be made of a new kind of force carrier — that is, a type of particle that mediates interactions between other particles.A warm and fuzzy darkness
The familiar photon is the force carrier of electromagnetism – it’s what creates electricity, magnetism, and light. Dark photons would be a force carrier for a new force of nature that does not operate at the usual scales in the usual scenarios (for example, in our laboratories or within the solar system, where we otherwise would have already observed it).
According to the study authors, the dark photons would still have a tiny bit of mass, and hence they could still account for the dark matter. Plus, because they’re force carriers, they may also interact amongst themselves and with other potential dark matter particles. In the models investigated by the team of astrophysicists, the dark photons are capable of one more trick: they can occasionally turn into a regular photon.Related stories—From Big Bang to present: Snapshots of our universe through time
—The 18 biggest unsolved mysteries in physics
—The 15 weirdest galaxies in the universe
In physics terms, the dark photons can “mix” with regular photons, very rarely swapping identities. When they do, the newly created photon goes on to do what regular photons always do: heat things up. The researchers performed the first ever simulations of the evolution of the universe, including the effects of these sneaky shapeshifting dark photons. They found that a particular combination of dark photon mass and the probability of changing into a regular photon could explain the heating discrepancy.
This result is a very far from a slam-dunk case for the existence of dark photons. A range of possibilities could also explain the Lyman-alpha results, like inaccurate observations or a poor understanding of (normal) astrophysical heating between galaxies. But it is an intriguing clue, and the results can be used as a springboard to continue exploring the viability of this exotic idea.
The health secretary has said that the cabinet is aware of the “pressure” on Chancellor Rachel Reeves amid volatile markets and a challenging broader economic picture – but appealed for the public to “give her time”.
Wes Streeting argued that the public “underestimates” the “amount of heavy-lifting” Ms Reeves has had to do and will have to continue to do, as he declared “total confidence” in her leadership in a staunch defence of her handling of the economy.
Separately, international development minister Anneliese Dodds, who attends cabinet, told Sky News that Ms Reeves has been “very clear about the long-term plan for our country” and she herself is “confident in that long-term plan”.
The comments from the two key ministers come after the past week saw a drop in the pound and an increase in government borrowing costs, which has fuelled speculation of more spending cuts or tax rises.
Streeting has ‘total confidence in chancellor’s leadership’
Speaking at the Jewish Labour Movement’s annual conference in north London, the health secretary acknowledged the fierce competition among all government departments for any available public funding from the Treasury, and told party members that all ministers “have to make choices and trade-offs” in where funding goes.
Mr Streeting went on to say that the chancellor and her deputy, Darren Jones, have “the hardest job of all because they have to make those choices across every bit of government spending, and they have to think about what’s in the interests of our overall economy and how we get businesses growing”.
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1:14
Chancellor’s ‘pragmatic’ approach to China
He said: “I think people continue to underestimate both the amount of heavy lifting she has had to do in her first six months, and the amount of heavy lifting she will have to do in her next six months.
“And the cabinet doesn’t underestimate that – we understand the choices she has to make, the pressure she is under.”
As a result, cabinet ministers all “have a responsibility” to both “make tough choices and drive reform and value for money” within their departments, and also be “drivers of economic growth”.
“Nothing in the last six months has shaken my conviction that economic growth is the number one priority,” he said.
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Continuing his defence of the chancellor’s handling of the economy so far, Mr Streeting said she is “trying to break us out of what has been the status quo and the economic orthodoxy of more than a decade”.
“People need to give her time, and they need to not forget that, without [Sir Keir Starmer’s] leadership, certainly we wouldn’t have won the last general election.
“Without Rachel’s leadership, we wouldn’t have won the last general election either. She built Labour’s economic credibility out of the ashes they were left in after the Corbyn leadership. And she has built that trust, built up that plan, and now she’s following through.”
He declared that he has “total confidence in the leadership that Rachel’s providing, and the leadership that the cabinet is following and driving with her, because all of us have to deliver economic growth for our country”.
Minister ‘confident in chancellor’s long-term plan’
Speaking in a separate session at the conference, Ms Dodds noted “speculation” about the fiscal headroom (the amount of money the chancellor will have available to spend), but said: “We have to focus on actually the evidence.
“And when we look at the evidence, we can see that the UK government has a chancellor who is very clear about the long-term plan for our country. She’s been delivering on it.”
Ms Dodds, who also attends cabinet, pointed to a “new fiscal system”, the chancellor’s new Industrial Strategy Council, as well as “record levels of investment under Rachel Reeves’s leadership”.
“I think it’s really important for us to focus on those fundamentals, on what has been achieved in a very short space of time. And I’m confident in that long-term plan that Rachel has been setting out.
“And we can already see the benefit of that, frankly, in terms of the UK’s reputation when it comes to public finances, but economic management more generally. Certainly that’s what I’ve heard internationally and keep hearing just now.”
Chancellor accused of having ‘fled to China’
The pair were speaking as the chancellor holds meetings in China in a bid to drum up investment for the UK economy, having ignored calls to cancel the long-planned trip because of economic turmoil at home.
Opposition parties have accused the chancellor of having “fled to China” rather than explain how she will fix the UK’s flatlining economy, and former prime minister Boris Johnson said Ms Reeves had “been rumbled” and said she should “make her way to HR and collect her P45 – or stay in China”.
Speaking during her trip, Ms Reeves said she would not alter her economic plans, with the October budget designed to return the UK to economic stability, and reiterated that “growth is the number one mission of this government”.
She said that “action” will be taken to meet the fiscal rules. That action is reported to include deeper spending cuts than the 5% efficiency savings already expected to be announced later this year, while cuts to the welfare bill are also said to be under consideration.
The health secretary has said that the cabinet is aware of the “pressure” on Chancellor Rachel Reeves amid volatile markets and a challenging broader economic picture – but appealed for the public to “give her time”.
Wes Streeting argued that the public “underestimates” the “amount of heavy-lifting” Ms Reeves has had to do and will have to continue to do, as he declared “total confidence” in her leadership in a staunch defence of her handling of the economy.
Separately, international development minister Anneliese Dodds, who attends cabinet, told Sky News that Ms Reeves has been “very clear about the long-term plan for our country” and she herself is “confident in that long-term plan”.
The comments from the two key ministers come after the past week saw a drop in the pound and an increase in government borrowing costs, which has fuelled speculation of more spending cuts or tax rises.
Streeting has ‘total confidence in chancellor’s leadership’
Speaking at the Jewish Labour Movement’s annual conference in north London, the health secretary acknowledged the fierce competition among all government departments for any available public funding from the Treasury, and told party members that all ministers “have to make choices and trade-offs” in where funding goes.
Mr Streeting went on to say that the chancellor and her deputy, Darren Jones, have “the hardest job of all because they have to make those choices across every bit of government spending, and they have to think about what’s in the interests of our overall economy and how we get businesses growing”.
Please use Chrome browser for a more accessible video player
1:14
Chancellor’s ‘pragmatic’ approach to China
He said: “I think people continue to underestimate both the amount of heavy lifting she has had to do in her first six months, and the amount of heavy lifting she will have to do in her next six months.
“And the cabinet doesn’t underestimate that – we understand the choices she has to make, the pressure she is under.”
As a result, cabinet ministers all “have a responsibility” to both “make tough choices and drive reform and value for money” within their departments, and also be “drivers of economic growth”.
“Nothing in the last six months has shaken my conviction that economic growth is the number one priority,” he said.
Follow Sky News on WhatsApp
Keep up with all the latest news from the UK and around the world by following Sky News
Continuing his defence of the chancellor’s handling of the economy so far, Mr Streeting said she is “trying to break us out of what has been the status quo and the economic orthodoxy of more than a decade”.
“People need to give her time, and they need to not forget that, without [Sir Keir Starmer’s] leadership, certainly we wouldn’t have won the last general election.
“Without Rachel’s leadership, we wouldn’t have won the last general election either. She built Labour’s economic credibility out of the ashes they were left in after the Corbyn leadership. And she has built that trust, built up that plan, and now she’s following through.”
He declared that he has “total confidence in the leadership that Rachel’s providing, and the leadership that the cabinet is following and driving with her, because all of us have to deliver economic growth for our country”.
Minister ‘confident in chancellor’s long-term plan’
Speaking in a separate session at the conference, Ms Dodds noted “speculation” about the fiscal headroom (the amount of money the chancellor will have available to spend), but said: “We have to focus on actually the evidence.
“And when we look at the evidence, we can see that the UK government has a chancellor who is very clear about the long-term plan for our country. She’s been delivering on it.”
Ms Dodds, who also attends cabinet, pointed to a “new fiscal system”, the chancellor’s new Industrial Strategy Council, as well as “record levels of investment under Rachel Reeves’s leadership”.
“I think it’s really important for us to focus on those fundamentals, on what has been achieved in a very short space of time. And I’m confident in that long-term plan that Rachel has been setting out.
“And we can already see the benefit of that, frankly, in terms of the UK’s reputation when it comes to public finances, but economic management more generally. Certainly that’s what I’ve heard internationally and keep hearing just now.”
Chancellor accused of having ‘fled to China’
The pair were speaking as the chancellor holds meetings in China in a bid to drum up investment for the UK economy, having ignored calls to cancel the long-planned trip because of economic turmoil at home.
Opposition parties have accused the chancellor of having “fled to China” rather than explain how she will fix the UK’s flatlining economy, and former prime minister Boris Johnson said Ms Reeves had “been rumbled” and said she should “make her way to HR and collect her P45 – or stay in China”.
Speaking during her trip, Ms Reeves said she would not alter her economic plans, with the October budget designed to return the UK to economic stability, and reiterated that “growth is the number one mission of this government”.
She said that “action” will be taken to meet the fiscal rules. That action is reported to include deeper spending cuts than the 5% efficiency savings already expected to be announced later this year, while cuts to the welfare bill are also said to be under consideration.
Anti-corruption minister Tulip Siddiq could lose her job if the investigation into her properties finds she broke government rules, a cabinet member has suggested.
She has referred herself to the prime minister’s independent adviser on ministers’ interests, Sir Laurie Magnus, following reports she lived in properties in London linked to allies of her aunt, Sheikh Hasina, the deposed prime minister of Bangladesh.
There have also been questions about trips she took to Russia alongside her aunt.
Ms Siddiq insists she has “done nothing wrong”.
As economic secretary to the Treasury, Ms Siddiq oversees anti-corruption efforts in the financial sector as part of her brief.
Mr Kyle told Sky News: “With Tulip, she’s referred herself straight away to this.
“There is a process under way and we know full well it will be a functional process, and the outcomes of it will be stuck to by the prime minister and this government, a complete contrast to what we’ve had in the past.”
He gave this answer after Trevor pointed out Labour would have been calling for a sacking if the roles were reversed and the Tories were in power.
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2:02
‘Tulip Siddiq will lose job if she broke rules’
Mr Kyle contrasted his party’s stance with the Conservative one – saying he called for an investigation into allegations of bullying from Priti Patel, and she “had to be dragged to that inquiry”.
He added that he let the inquiry pan out.
“The results came out, she was found guilty, and no action happened,” Mr Kyle said.
His response came after Conservative leader Kemi Badenoch called for Ms Siddiq to be sacked yesterday.
Shadow chancellor Mel Stride repeated the calls today to Sky News.
He said: “What is not right is that the prime minister is not moving her out of that position and getting her to step down
“Because she is the anti-corruption minister, she has serious charges laid against her now, or serious accusations around corruption, and it’s going to be really impossible for her to do that job under current circumstances.
“So she should step down, and the prime minister needs to get a grip of that.”
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