Albert Einstein’s general theory of relativity “didn’t have to be”
Hello, and welcome to November’s Lost in Space-Time, the monthly physics newsletter that unpicks the fabric of the universe and attempts to stitch it back together in a slightly different way. To receive this free, monthly newsletter in your inbox, sign up here.
Einstein’s forgotten twisted universe
There’s a kind of inevitability about the fact that, if you write a regular newsletter about fundamental physics, you’ll regularly find yourself banging on about Albert Einstein. As much as it comes with the job, I also make no apology for it: he is a towering figure in the history of not just fundamental physics, but science generally.
A point that historians of science sometimes make about his most monumental achievement, the general theory of relativity, is that, pretty much uniquely, it was a theory that didn’t have to be. When you look at the origins of something like Charles Darwin’s theory of evolution by natural selection, for example – not to diminish his magisterial accomplishment in any way – you’ll find that other people had been scratching around similar ideas surrounding the origin and change of species for some time as a response to the burgeoning fossil record, among other discoveries.
Even Einstein’s special relativity, the precursor to general relativity that first introduced the idea of warping space and time, responded to a clear need (first distinctly identified with the advent of James Clerk Maxwell’s laws of electromagnetism in the 1860s) to explain why the speed of light appeared to be an absolute constant.
When Einstein presented general relativity to the world in 1915, there was nothing like that. We had a perfectly good working theory of gravity, the one developed by Isaac Newton more than two centuries earlier. True, there was a tiny problem in that it couldn’t explain some small wobbles in the orbit of Mercury, but they weren’t of the size that demanded we tear up our whole understanding of space, time, matter and the relationship between them. But pretty much everything we know (and don’t know) about the wider universe today stems from general relativity: the expanding big bang universe and the standard model of cosmology, dark matter and energy, black holes, gravitational waves, you name it.
So why am I banging on about this? Principally because, boy, do we need a new idea in cosmology now – and in a weird twist of history, it might just be Einstein who supplies it. I’m talking about an intriguing feature by astrophysicist Paul M. Sutter in the magazine last month . It deals with perhaps general relativity’s greatest (perceived, at least) weakness – the way it doesn’t mesh with other bits of physics, which are all explained by quantum theory these days. The mismatch exercised Einstein a great deal, and he spent much of his later years engaged in a fruitless quest to unify all of physics.
Perhaps his most promising attempt came with a twist – literally – on general relativity that Einstein played about with early on. By developing a mathematical language not just for how space-time bends (which is the basis of how gravity is created within relativity) but for how it twists, he hoped to create a theory that also explained the electromagnetic force. He succeeded in the first bit, creating a description of how massive, charged objects might twist space-time into mini-cyclones around them. But it didn’t create a convincing description of electromagnetism, and Einstein quietly dropped the theory.
Well, the really exciting bit, as Sutter describes, is that this “teleparallel gravity” seems to be back in a big way. Many cosmologists now think it could be a silver bullet to explain away some of the most mysterious features of today’s universe, such as the nature of dark matter and dark energy and the troublesome period of faster-than-light inflation right at the moment of the big bang that is invoked to explain features of today’s universe, such as its extraordinary smoothness. Not only that, but there could be a way to test the theory soon. I’d recommend reading the feature to get all the details, but in the meantime, it’s about as exciting a development as you’ll get in cosmology these days.
Is the universe fine-tuned?
Let’s take just a quick dip into the physics arXiv preprint server, where the latest research is put up. One paper that caught my eye recently has the inviting title “Life, the universe and the hidden meaning of everything” . It’s by Zhi-Wei Wang at the College of Physics in China and Samuel L. Braunstein at the University of York in the UK, and it deals with a question that’s been bugging a lot of physicists and cosmologists ever since we started making detailed measurements of the universe and developing cogent theories to explain what we see: why does everything in the universe (the strengths of the various forces, the masses of fundamental particles, etc.) seem so perfectly tuned to allow the existence of observers like us to ask the question?
This has tended to take cosmologists and physicists down one of two avenues. The first says things are how they are because that’s how they’re made. For some, that sails very close to an argument via intelligent design, aka the existence of god. The other avenue tends to be some form of multiverse argument: our universe is as it is because we are here to observe it (we could hardly be here to observe it if it weren’t), but it is one of a random subset of many possible universes that happen to be conducive to intelligent life arising.
This paper examines more closely a hypothesis from British physicist Dennis Sciama (doctoral supervisor to the stars: among his students in the 1960s and 1970s were Stephen Hawking, quantum computing pioneer David Deutsch and the UK’s astronomer royal, Martin Rees ) that if ours were a random universe, there would be a statistical pattern in its fundamental parameters that would give us evidence of that. In this paper, the researchers argue that the logic is actually reversed. In their words: “Were our universe random, it could give the false impression of being intelligently designed, with the fundamental constants appearing to be fine-tuned to a strong probability for life to emerge and be maintained.”
Full disclosure – I’m writing something on this very subject for New Scientist’s 65th-anniversary issue, due out on 20 November. Read more there!
Closing the quantum loopholes
While I’m banging on about Einstein, I stumbled across one of my favourite features I’ve worked on while at the magazine the other day, and thought it was worth sharing. Called “Reality check: Closing the quantum loopholes”, it’s from 2011, a full 10 years ago, but the idea it deals with stretches back way before that – and is still a very live one.
The basic question is: is quantum theory a true description of reality, or are its various weirdnesses – not least the “entanglement” of quantum objects over vast distances – indications of goings-on in an underlying layer of reality not described by quantum theory (or indeed any other theory to date)? I talked about entanglement quite a bit in last month’s newsletter, so I won’t go into its workings here.
The alternative idea of “hidden variables” explaining the workings of the quantum world goes back to a famous paper published by Einstein and two collaborators, Nathan Rosen and Boris Podolsky, back in 1935. It led Einstein into a long-drawn-out debate about the nature of quantum theory with another of its pioneers, Niels Bohr, that continued decorously right until Einstein’s death in 1955. It wasn’t until the 1980s that we began to have the theoretical and experimental capabilities to actually pit the two pictures against one another.
The observatories atop the volcano Teide on Tenerife were one scene of a bold test of quantum reality.
Phil Crean A/ Alamy
I love the story not just for this rich history, but also for the way that, after each iteration of the experiments – every time showing that quantum theory, and entanglement, are the “right” explanation for what is going on, whatever they might mean – the physicists found another loophole in the experiments that might allow Einstein’s hidden variable idea back into the frame again.
That led them to some pretty impressive feats of experimental derring-do to close the loopholes again – the feature opens with a group of modern physicists shooting single photons between observatories on Tenerife and La Palma in the Canary Islands. In an update to the story that we published in 2018 (with the rather explicit title “Einstein was wrong: Why ‘normal’ physics can’t explain reality” ), they even reproduced the result with photons coming at us from galaxies billions of light years away – proving that, if not the whole universe, then a goodly proportion of it follows quantum rules. You can’t win ‘em all, Einstein.
Coming up
One reason I’ve been thinking particularly frequently about Einstein and his work lately is that I’ve been putting together the latest New Scientist Essential Guidecalled “Einstein’s Universe”. It’s a survey of his theories of relativity and all those things that came out of it: the big bang universe and the standard model of cosmology, dark matter and energy, gravitational waves, black holes and, of course, the search for that elusive unifying theory of physics. I’ve just putting the finishing touches to the Essential Guide with my left hand as I type this, and I think it’s a fair expectation that you’ll find me banging on about that (and Einstein) a lot more next month.
Also in New Scientist
1. Talking of fine-tuned universes, if you haven’t done so already, you can still catch up with Brian Clegg’s New Scientist Event talk, “The Patterns That Explain the Universe”, from last month, available on demand.
2. If you’re fan of big ideas (I hope that’s why you’re here) and like casting your net a little wider than just physics, then a ticket to our Big Thinkers series of live events gives you access to 10 talks from top researchers from across the board, including Harvard astronomer Avi Loeb on the search for extraterrestrial life and Michelle Simmons and John Martinis on quantum computing.
3. It happened just after my last newsletter, but it would be remiss not to mention the awarding of this year’s Nobel prize to three researchers who played a leading role in advancing our understanding of chaotic systems – notably the climate. You can find out more about what they did here.
That’s it for now. Thank you for reading! If you have any comments or questions, you can let me know by emailing me at [email protected] and I’ll try to answer them in an upcoming newsletter. If you know someone who might enjoy Lost in Space-Time, please forward it on. If you haven’t yet, you can sign up to get it in your inbox every week here.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
The European Space Agency is fast-tracking a new mission called Ramses, which will fly to near-Earth asteroid 99942 Apophis and join the space rock in 2029 when it comes very close to our planet — closer even than the region where geosynchronous satellites sit.
Ramses is short for Rapid Apophis Mission for Space Safety and, as its name suggests, is the next phase in humanity’s efforts to learn more about near-Earth asteroids (NEOs) and how we might deflect them should one ever be discovered on a collision course with planet Earth.
In order to launch in time to rendezvous with Apophis in February 2029, scientists at the European Space Agency have been given permission to start planning Ramses even before the multinational space agency officially adopts the mission. The sanctioning and appropriation of funding for the Ramses mission will hopefully take place at ESA’s Ministerial Council meeting (involving representatives from each of ESA’s member states) in November of 2025. To arrive at Apophis in February 2029, launch would have to take place in April 2028, the agency says.
This is a big deal because large asteroids don’t come this close to Earth very often. It is thus scientifically precious that, on April 13, 2029, Apophis will pass within 19,794 miles (31,860 kilometers) of Earth. For comparison, geosynchronous orbit is 22,236 miles (35,786 km) above Earth’s surface. Such close fly-bys by asteroids hundreds of meters across (Apophis is about 1,230 feet, or 375 meters, across) only occur on average once every 5,000 to 10,000 years. Miss this one, and we’ve got a long time to wait for the next.
When Apophis was discovered in 2004, it was for a short time the most dangerous asteroid known, being classified as having the potential to impact with Earth possibly in 2029, 2036, or 2068. Should an asteroid of its size strike Earth, it could gouge out a crater several kilometers across and devastate a country with shock waves, flash heating and earth tremors. If it crashed down in the ocean, it could send a towering tsunami to devastate coastlines in multiple countries.
Over time, as our knowledge of Apophis’ orbit became more refined, however, the risk of impact greatly went down. Radar observations of the asteroid in March of 2021 reduced the uncertainty in Apophis’ orbit from hundreds of kilometers to just a few kilometers, finally removing any lingering worries about an impact — at least for the next 100 years. (Beyond 100 years, asteroid orbits can become too unpredictable to plot with any accuracy, but there’s currently no suggestion that an impact will occur after 100 years.) So, Earth is expected to be perfectly safe in 2029 when Apophis comes through. Still, scientists want to see how Apophis responds by coming so close to Earth and entering our planet’s gravitational field.
Breaking space news, the latest updates on rocket launches, skywatching events and more!
“There is still so much we have yet to learn about asteroids but, until now, we have had to travel deep into the solar system to study them and perform experiments ourselves to interact with their surface,” said Patrick Michel, who is the Director of Research at CNRS at Observatoire de la Côte d’Azur in Nice, France, in a statement. “Nature is bringing one to us and conducting the experiment itself. All we need to do is watch as Apophis is stretched and squeezed by strong tidal forces that may trigger landslides and other disturbances and reveal new material from beneath the surface.”
The Goldstone radar’s imagery of asteroid 99942 Apophis as it made its closest approach to Earth, in March 2021. (Image credit: NASA/JPL–Caltech/NSF/AUI/GBO)
By arriving at Apophis before the asteroid’s close encounter with Earth, and sticking with it throughout the flyby and beyond, Ramses will be in prime position to conduct before-and-after surveys to see how Apophis reacts to Earth. By looking for disturbances Earth’s gravitational tidal forces trigger on the asteroid’s surface, Ramses will be able to learn about Apophis’ internal structure, density, porosity and composition, all of which are characteristics that we would need to first understand before considering how best to deflect a similar asteroid were one ever found to be on a collision course with our world.
Besides assisting in protecting Earth, learning about Apophis will give scientists further insights into how similar asteroids formed in the early solar system, and, in the process, how planets (including Earth) formed out of the same material.
One way we already know Earth will affect Apophis is by changing its orbit. Currently, Apophis is categorized as an Aten-type asteroid, which is what we call the class of near-Earth objects that have a shorter orbit around the sun than Earth does. Apophis currently gets as far as 0.92 astronomical units (137.6 million km, or 85.5 million miles) from the sun. However, our planet will give Apophis a gravitational nudge that will enlarge its orbit to 1.1 astronomical units (164.6 million km, or 102 million miles), such that its orbital period becomes longer than Earth’s.
It will then be classed as an Apollo-type asteroid.
Ramses won’t be alone in tracking Apophis. NASA has repurposed their OSIRIS-REx mission, which returned a sample from another near-Earth asteroid, 101955 Bennu, in 2023. However, the spacecraft, renamed OSIRIS-APEX (Apophis Explorer), won’t arrive at the asteroid until April 23, 2029, ten days after the close encounter with Earth. OSIRIS-APEX will initially perform a flyby of Apophis at a distance of about 2,500 miles (4,000 km) from the object, then return in June that year to settle into orbit around Apophis for an 18-month mission.
Related Stories:
Furthermore, the European Space Agency still plans on launching its Hera spacecraft in October 2024 to follow-up on the DART mission to the double asteroid Didymos and Dimorphos. DART impacted the latter in a test of kinetic impactor capabilities for potentially changing a hazardous asteroid’s orbit around our planet. Hera will survey the binary asteroid system and observe the crater made by DART’s sacrifice to gain a better understanding of Dimorphos’ structure and composition post-impact, so that we can place the results in context.
The more near-Earth asteroids like Dimorphos and Apophis that we study, the greater that context becomes. Perhaps, one day, the understanding that we have gained from these missions will indeed save our planet.
