What is the 'dark dimensions' hypothesis in string theory?

The dark dimensions hypothesis suggests that extra spatial dimensions, predicted by string theory, could potentially explain the existence of dark matter. These dimensions are assumed to be rolled up to very small sizes, but some theories propose certain dimensions could be larger and measurable.

What are the key properties of Cornell's new fast-charging battery?

Researchers at Cornell University developed a new battery anode using lithium and indium. Indium's low migration energy barrier allows ions to move easily, enabling charging in about 2 minutes, and it demonstrates stability over 1,000 cycles.

How is AI being used to control nuclear fusion plasma?

AI systems are being trained on data from fusion reactors to predict and control plasma instabilities in real-time. Researchers from DeepMind and teams in Japan and the US have used AI and digital twins (models) to steer plasma, making fusion energy more efficient and controllable.

What are the goals of the proposed Future Circular Collider (FCC) at CERN?

The FCC aims to collide electrons and protons at much higher energies than the LHC, primarily to study Higgs bosons and potentially discover the nature of dark matter and dark energy, leading to a more complete theory of the universe.

Why is carbon dioxide removal considered crucial but also challenging?

Limiting global warming to 2°C relies heavily on carbon dioxide removal (CDR), but current estimates, particularly for methods like BECCS, require vast amounts of land and could threaten food security. The speaker argues that the IPCC's projections are unrealistic.

What are naked singularities and how might they relate to dark matter?

Naked singularities are theoretical points in spacetime without a horizon, unlike black holes. A new paper suggests they could have formed in the early universe, potentially existing throughout the cosmos and serving as a more viable candidate for dark matter than primordial black holes.

Key Moments

(Audio-only Podcast) String theory nonsense makes comeback -- And other news of the week

Sabine Hossenfelder

Science & Technology5 min read44 min video

Feb 16, 2024|23,692 views|616|150

science without the gobbledygoook hossenfelder

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Key Moments

TL;DR

Science news: Social media's mental health link debated, string theory's dark matter comeback, fast charging batteries, fusion control, CERN collider plans, climate mitigation challenges, and naked singularities for dark matter.

Key Insights

The scientific consensus on a direct causal link between social media use and adolescent mental health issues is inconclusive, with studies showing small effects or highlighting other factors like bullying and family support as more influential.

A new research program revives the idea of large extra dimensions to explain dark matter, suggesting that gravity, unlike other forces, propagates in these dimensions, and 'massive gravitons' in these dimensions could constitute dark matter.

Researchers have developed a new battery anode using lithium and indium that can charge in approximately 2 minutes and maintain stability over 1,000 cycles, though its energy density is currently lower than standard lithium-ion batteries.

A new method uses a 'digital twin' (a computer model updated with real-time data) to control plasma in a stellarator fusion device, showing promise for real-time steering and potentially increasing the efficiency of fusion energy.

Plans for CERN's Future Circular Collider (FCC) have been detailed, proposing a 91km electron-positron collider followed by a proton-proton collider, with a stated goal of understanding dark matter and dark energy, though the efficacy for these goals is questioned.

A new study suggests that IPCC projections for carbon dioxide removal, particularly from bioenergy with carbon capture and storage (BECCS), are unrealistic, estimating significantly lower achievable removal rates and highlighting potential negative impacts on land use and food security.

A recent paper proposes that 'naked singularities' (singularities without a surrounding event horizon), potentially formed in the early universe, could be a viable candidate for dark matter, circumventing some observational constraints that limit primordial black hole candidates.

DEBATING SOCIAL MEDIA'S MENTAL HEALTH IMPACT

The episode begins by addressing the debated link between social media use and adolescent mental health. Meta CEO Mark Zuckerberg's claim that the scientific evidence does not conclusively prove a link is discussed. While global mental health has been stable, adolescent mental health, especially among girls, has declined in some countries. However, studies on social media's impact yield mixed results; some show very small correlations, while others suggest it's one of the least influential factors compared to issues like bullying or lack of family support. The complexity and context-dependency of psychological and sociological research are highlighted as reasons for inconclusive findings.

STRING THEORY AND THE RETURN OF LARGE EXTRA DIMENSIONS FOR DARK MATTER

A resurgence in string theory research is exploring the concept of 'dark dimensions' to explain dark matter. This idea posits that our universe has more than the observable four dimensions, with six extra dimensions curled up. A new paper suggests these extra dimensions, if large enough, could host 'massive gravitons' which might constitute dark matter. These dimensions are hypothesized to be about one micrometer in size, theoretically testable by experiments. The theory relies on gravity experiencing these extra dimensions, while normal matter remains confined to our three-dimensional 'brane'.

ADVANCING BATTERY TECHNOLOGY FOR FASTER CHARGING

Innovations in battery technology aim to shorten charging times. A new experimental battery from Cornell University utilizes a lithium and indium anode, enabling a charge time of approximately 2 minutes and maintaining stability over 1,000 cycles. While promising, this technology has a lower energy density than current lithium-ion batteries and faces challenges in scaling indium production. The speaker questions the necessity of such rapid charging, suggesting that range anxiety is primarily about the need to stop at all, rather than the duration of the charge itself.

CONTROLLING PLASMA FOR NUCLEAR FUSION WITH DIGITAL TWINS

Progress in nuclear fusion research includes controlling plasma using advanced computing methods. A team from Japan and the US has used a 'digital twin'—a real-time computer replica—to control plasma in a stellarator. This method, similar to weather forecasting, uses ensemble forecasting to predict plasma behavior. While previous AI-based methods have shown success in steering plasma, this new approach incorporates more physics. Neither of these methods currently controls an ongoing fusion reaction, but they represent significant steps towards more stable and efficient fusion energy.

CERN'S FUTURE CIRCULAR COLLIDER PLANS AND SCIENTIFIC GOALS

CERN is planning a Future Circular Collider (FCC), a massive underground ring collider. The first stage would collide electrons and positrons to produce Higgs bosons, followed by a second stage colliding protons and heavy ions. The project's stated goal, echoed by CERN's Director General, is to understand dark matter and dark energy, leading to a new theory of the universe. However, the speaker expresses skepticism, comparing it to past claims about the Large Hadron Collider's ability to find dark matter, which proved unfounded, labeling such statements as potentially deliberate misinformation.

CLIMATE CHANGE MITIGATION: UNREALISTIC CARBON DIOXIDE REMOVAL PROJECTIONS

A new study critically assesses the Intergovernmental Panel on Climate Change (IPCC)'s mitigation plans, particularly concerning carbon dioxide removal (CDR). The study argues that IPCC projections for CDR methods like Bioenergy with Carbon Capture and Storage (BECCS) are unrealistic, estimating the required land use would be enormous and could lead to food insecurity. The authors suggest that actual achievable CDR might be significantly less than the IPCC's estimates, implying that even the IPCC's 2°C warming limit targets may be unattainable without more realistic CDR strategies or stronger emissions reductions.

SINGULARITIES AS A CANDIDATE FOR DARK MATTER

An intriguing new hypothesis suggests that dark matter could be composed of 'naked singularities'—points of infinite density without the event horizons found in black holes. These could have formed in the early universe from density fluctuations. Unlike primordial black holes, which face observational constraints, naked singularities might offer a more viable explanation for dark matter due to potentially different observational signatures. While the mathematical compatibility with observations needs further development, this idea presents a novel avenue in the search for dark matter's composition.

Mentioned in This Episode

●Supplements

●Products

●Tools

●Companies

●Organizations

●Books

●Concepts

●People Referenced

Common Questions

The bulk of scientific evidence does not strongly support a direct link between social media use and widespread adolescent mental health crises, though some studies show small effects. The speaker suggests that other factors like bullying or family support might be more significant.

Topics

Nuclear Fusion Technology & Innovation Particle Physics Dark Matter General Relativity Carbon Capture Advancing Batteries Climate Change Mitigation

Mentioned in this video

Concepts

Higgs boson

A fundamental particle discovered at the LHC in 2012, which particle physicists want to study further with the FCC.

String Theory

An approach to a theory of everything invented in the 1970s that requires nine dimensions of space and is the basis for new research into dark dimensions.

Primordial black holes

Black holes potentially formed in the early universe which have been considered as candidates for dark matter but largely discarded due to observational conflicts.

Products

Samsung S24

The speaker's new phone, which takes about 60 to 90 minutes to fully charge.

Large Hadron Collider (LHC)

Large Hadron Collider, a particle accelerator used for comparison to the proposed Future Circular Collider (FCC) and previously believed to be able to 'fight dark matter'.

People

Mark Zuckerberg

Meta CEO who testified in the US Senate about social media and its link to adolescent mental health, stating the scientific evidence does not support a strong link.

Jonathan Haidt

American psychologist and vocal critic of social media use for children, whose arguments are discussed in relation to scientific studies.

Max Planck

Physicist after whom the Planck length is named, and who made the observation that science progresses one funeral at a time.

Companies